head 1.9; access; symbols libarchive-3-8-7:1.1.1.11 libarchive-3-8-6:1.1.1.11 pkgsrc-2026Q1:1.9.0.12 pkgsrc-2026Q1-base:1.9 libarchive-3-8-5:1.1.1.11 libarchive-3-8-4:1.1.1.11 pkgsrc-2025Q4:1.9.0.10 pkgsrc-2025Q4-base:1.9 libarchive-3-8-3:1.1.1.11 libarchive-3-8-2:1.1.1.11 pkgsrc-2025Q3:1.9.0.8 pkgsrc-2025Q3-base:1.9 libarchive-3-8-1:1.1.1.11 pkgsrc-2025Q2:1.9.0.6 pkgsrc-2025Q2-base:1.9 libarchive-3-8-0:1.1.1.11 libarchive-3-7-9:1.1.1.11 pkgsrc-2025Q1:1.9.0.4 pkgsrc-2025Q1-base:1.9 pkgsrc-2024Q4:1.9.0.2 pkgsrc-2024Q4-base:1.9 libarchive-3-7-7:1.1.1.11 pkgsrc-2024Q3:1.8.0.6 pkgsrc-2024Q3-base:1.8 libarchive-3-7-5:1.1.1.10 pkgsrc-2024Q2:1.8.0.4 pkgsrc-2024Q2-base:1.8 libarchive-3-7-4:1.1.1.10 libarchive-3-7-3:1.1.1.10 pkgsrc-2024Q1:1.8.0.2 pkgsrc-2024Q1-base:1.8 libarchive-3-7-2:1.1.1.10 pkgsrc-2023Q4:1.7.0.30 pkgsrc-2023Q4-base:1.7 pkgsrc-2023Q3:1.7.0.28 pkgsrc-2023Q3-base:1.7 pkgsrc-2023Q2:1.7.0.26 pkgsrc-2023Q2-base:1.7 pkgsrc-2023Q1:1.7.0.24 pkgsrc-2023Q1-base:1.7 pkgsrc-2022Q4:1.7.0.22 pkgsrc-2022Q4-base:1.7 pkgsrc-2022Q3:1.7.0.20 pkgsrc-2022Q3-base:1.7 pkgsrc-2022Q2:1.7.0.18 pkgsrc-2022Q2-base:1.7 pkgsrc-2022Q1:1.7.0.16 pkgsrc-2022Q1-base:1.7 pkgsrc-2021Q4:1.7.0.14 pkgsrc-2021Q4-base:1.7 pkgsrc-2021Q3:1.7.0.12 pkgsrc-2021Q3-base:1.7 pkgsrc-2021Q2:1.7.0.10 pkgsrc-2021Q2-base:1.7 pkgsrc-2021Q1:1.7.0.8 pkgsrc-2021Q1-base:1.7 pkgsrc-2020Q4:1.7.0.6 pkgsrc-2020Q4-base:1.7 pkgsrc-2020Q3:1.7.0.4 pkgsrc-2020Q3-base:1.7 pkgsrc-2020Q2:1.7.0.2 pkgsrc-2020Q2-base:1.7 pkgsrc-2020Q1:1.6.0.4 pkgsrc-2020Q1-base:1.6 pkgsrc-2019Q4:1.6.0.6 pkgsrc-2019Q4-base:1.6 pkgsrc-2019Q3:1.6.0.2 pkgsrc-2019Q3-base:1.6 libarchive-3-4-0:1.1.1.9 libarchive-3-3-3:1.1.1.8 pkgsrc-2019Q2:1.5.0.18 pkgsrc-2019Q2-base:1.5 pkgsrc-2019Q1:1.5.0.16 pkgsrc-2019Q1-base:1.5 pkgsrc-2018Q4:1.5.0.14 pkgsrc-2018Q4-base:1.5 pkgsrc-2018Q3:1.5.0.12 pkgsrc-2018Q3-base:1.5 pkgsrc-2018Q2:1.5.0.10 pkgsrc-2018Q2-base:1.5 pkgsrc-2018Q1:1.5.0.8 pkgsrc-2018Q1-base:1.5 pkgsrc-2017Q4:1.5.0.6 pkgsrc-2017Q4-base:1.5 pkgsrc-2017Q3:1.5.0.4 pkgsrc-2017Q3-base:1.5 libarchive-3-3-2:1.1.1.8 pkgsrc-2017Q2:1.4.0.4 pkgsrc-2017Q2-base:1.4 pkgsrc-2017Q1:1.4.0.2 pkgsrc-2017Q1-base:1.4 libarchive-3-3-1:1.1.1.7 pkgsrc-2016Q4:1.3.0.6 pkgsrc-2016Q4-base:1.3 pkgsrc-2016Q3:1.3.0.4 pkgsrc-2016Q3-base:1.3 pkgsrc-2016Q2:1.3.0.2 pkgsrc-2016Q2-base:1.3 libarchive-3-2-1:1.1.1.6 pkgsrc-2016Q1:1.2.0.10 pkgsrc-2016Q1-base:1.2 pkgsrc-2015Q4:1.2.0.8 pkgsrc-2015Q4-base:1.2 pkgsrc-2015Q3:1.2.0.6 pkgsrc-2015Q3-base:1.2 pkgsrc-2015Q2:1.2.0.4 pkgsrc-2015Q2-base:1.2 pkgsrc-2015Q1:1.2.0.2 pkgsrc-2015Q1-base:1.2 pkgsrc-2014Q4:1.1.1.5.0.36 pkgsrc-2014Q4-base:1.1.1.5 pkgsrc-2014Q3:1.1.1.5.0.34 pkgsrc-2014Q3-base:1.1.1.5 pkgsrc-2014Q2:1.1.1.5.0.32 pkgsrc-2014Q2-base:1.1.1.5 pkgsrc-2014Q1:1.1.1.5.0.30 pkgsrc-2014Q1-base:1.1.1.5 pkgsrc-2013Q4:1.1.1.5.0.28 pkgsrc-2013Q4-base:1.1.1.5 pkgsrc-2013Q3:1.1.1.5.0.26 pkgsrc-2013Q3-base:1.1.1.5 pkgsrc-2013Q2:1.1.1.5.0.24 pkgsrc-2013Q2-base:1.1.1.5 pkgsrc-2013Q1:1.1.1.5.0.22 pkgsrc-2013Q1-base:1.1.1.5 pkgsrc-2012Q4:1.1.1.5.0.20 pkgsrc-2012Q4-base:1.1.1.5 pkgsrc-2012Q3:1.1.1.5.0.18 pkgsrc-2012Q3-base:1.1.1.5 pkgsrc-2012Q2:1.1.1.5.0.16 pkgsrc-2012Q2-base:1.1.1.5 pkgsrc-2012Q1:1.1.1.5.0.14 pkgsrc-2012Q1-base:1.1.1.5 pkgsrc-2011Q4:1.1.1.5.0.12 pkgsrc-2011Q4-base:1.1.1.5 pkgsrc-2011Q3:1.1.1.5.0.10 pkgsrc-2011Q3-base:1.1.1.5 pkgsrc-2011Q2:1.1.1.5.0.8 pkgsrc-2011Q2-base:1.1.1.5 pkgsrc-2011Q1:1.1.1.5.0.6 pkgsrc-2011Q1-base:1.1.1.5 pkgsrc-2010Q4:1.1.1.5.0.4 pkgsrc-2010Q4-base:1.1.1.5 pkgsrc-2010Q3:1.1.1.5.0.2 pkgsrc-2010Q3-base:1.1.1.5 libarchive-2-8-4:1.1.1.5 pkgsrc-2010Q2:1.1.1.4.0.4 pkgsrc-2010Q2-base:1.1.1.4 pkgsrc-2010Q1:1.1.1.4.0.2 pkgsrc-2010Q1-base:1.1.1.4 libarchive-2-8-3:1.1.1.4 libarchive-2-8-2:1.1.1.3 libarchive-2-8-0:1.1.1.2 pkgsrc-2009Q4:1.1.1.1.0.22 pkgsrc-2009Q4-base:1.1.1.1 pkgsrc-2009Q3:1.1.1.1.0.20 pkgsrc-2009Q3-base:1.1.1.1 pkgsrc-2009Q2:1.1.1.1.0.18 pkgsrc-2009Q2-base:1.1.1.1 pkgsrc-2009Q1:1.1.1.1.0.16 pkgsrc-2009Q1-base:1.1.1.1 pkgsrc-2008Q4:1.1.1.1.0.14 pkgsrc-2008Q4-base:1.1.1.1 pkgsrc-2008Q3:1.1.1.1.0.12 pkgsrc-2008Q3-base:1.1.1.1 cube-native-xorg:1.1.1.1.0.10 cube-native-xorg-base:1.1.1.1 pkgsrc-2008Q2:1.1.1.1.0.8 pkgsrc-2008Q2-base:1.1.1.1 cwrapper:1.1.1.1.0.6 pkgsrc-2008Q1:1.1.1.1.0.4 pkgsrc-2008Q1-base:1.1.1.1 pkgsrc-2007Q4:1.1.1.1.0.2 pkgsrc-2007Q4-base:1.1.1.1 libarchive-2-4-0:1.1.1.1 KIENTZLE:1.1.1; locks; strict; comment @# @; 1.9 date 2024.10.19.05.39.58; author adam; state Exp; branches; next 1.8; commitid fYRSlpIWMYluweuF; 1.8 date 2024.01.18.18.00.16; author adam; state Exp; branches; next 1.7; commitid hNXpsHx3SuHqsXUE; 1.7 date 2020.05.26.09.16.41; author nia; state Exp; branches; next 1.6; commitid nNhsdZACz3PjmJ9C; 1.6 date 2019.09.22.09.55.08; author joerg; state Exp; branches; next 1.5; commitid FdPvRjF4OzwBwZDB; 1.5 date 2017.08.01.22.26.23; author joerg; state Exp; branches; next 1.4; commitid 32clTfkmVE8bPy1A; 1.4 date 2017.02.25.21.11.19; author joerg; state Exp; branches; next 1.3; commitid rW8QfCWrsCO1snHz; 1.3 date 2016.06.20.17.24.57; author joerg; state Exp; branches; next 1.2; commitid ArUvympBjfBseebz; 1.2 date 2015.01.17.12.44.49; author adam; state Exp; branches; next 1.1; commitid yy7e1hLrfmA2pn6y; 1.1 date 2007.11.30.21.25.33; author joerg; state Exp; branches 1.1.1.1; next ; 1.1.1.1 date 2007.11.30.21.25.33; author joerg; state Exp; branches; next 1.1.1.2; 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This release fixes a tar regression introduced in libarchive 3.7.5 Important bugfixes. tar: clean up linkpath between entries tar: fix memory leaks when processing symlinks or parsing pax headers iso: be more cautious about parsing ISO-9660 timestamps @ text @4mTAR24m(5) File Formats Manual 4mTAR24m(5) 1mNAME0m tar — format of tape archive files 1mDESCRIPTION0m The 1mtar 22marchive format collects any number of files, directories, and other file system objects (symbolic links, device nodes, etc.) into a single stream of bytes. The format was originally designed to be used with tape drives that operate with fixed-size blocks, but is widely used as a general packaging mechanism. 1mGeneral Format0m A 1mtar 22marchive consists of a series of 512-byte records. Each file sys‐ tem object requires a header record which stores basic metadata (path‐ name, owner, permissions, etc.) and zero or more records containing any file data. The end of the archive is indicated by two records consist‐ ing entirely of zero bytes. For compatibility with tape drives that use fixed block sizes, programs that read or write tar files always read or write a fixed number of records with each I/O operation. These “blocks” are always a multiple of the record size. The maximum block size supported by early imple‐ mentations was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms “block” and “record” here are not entirely standard; this document follows the convention established by John Gilmore in docu‐ menting 1mpdtar22m.) 1mOld-Style Archive Format0m The original tar archive format has been extended many times to include additional information that various implementors found necessary. This section describes the variant implemented by the tar command included in Version 7 AT&T UNIX, which seems to be the earliest widely-used ver‐ sion of the tar program. The header record for an old-style 1mtar 22marchive consists of the follow‐ ing: struct header_old_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char linkflag[1]; char linkname[100]; char pad[255]; }; All unused bytes in the header record are filled with nulls. 4mname24m Pathname, stored as a null-terminated string. Early tar imple‐ mentations only stored regular files (including hardlinks to those files). One common early convention used a trailing "/" character to indicate a directory name, allowing directory per‐ missions and owner information to be archived and restored. 4mmode24m File mode, stored as an octal number in ASCII. 4muid24m, 4mgid0m User id and group id of owner, as octal numbers in ASCII. 4msize24m Size of file, as octal number in ASCII. For regular files only, this indicates the amount of data that follows the header. In particular, this field was ignored by early tar im‐ plementations when extracting hardlinks. Modern writers should always store a zero length for hardlink entries. 4mmtime24m Modification time of file, as an octal number in ASCII. This indicates the number of seconds since the start of the epoch, 00:00:00 UTC January 1, 1970. Note that negative values should be avoided here, as they are handled inconsistently. 4mchecksum0m Header checksum, stored as an octal number in ASCII. To com‐ pute the checksum, set the checksum field to all spaces, then sum all bytes in the header using unsigned arithmetic. This field should be stored as six octal digits followed by a null and a space character. Note that many early implementations of tar used signed arithmetic for the checksum field, which can cause interoperability problems when transferring archives be‐ tween systems. Modern robust readers compute the checksum both ways and accept the header if either computation matches. 4mlinkflag24m, 4mlinkname0m In order to preserve hardlinks and conserve tape, a file with multiple links is only written to the archive the first time it is encountered. The next time it is encountered, the 4mlinkflag0m is set to an ASCII ‘1’ and the 4mlinkname24m field holds the first name under which this file appears. (Note that regular files have a null value in the 4mlinkflag24m field.) Early tar implementations varied in how they terminated these fields. The tar command in Version 7 AT&T UNIX used the following conventions (this is also documented in early BSD manpages): the pathname must be null-terminated; the mode, uid, and gid fields must end in a space and a null byte; the size and mtime fields must end in a space; the check‐ sum is terminated by a null and a space. Early implementations filled the numeric fields with leading spaces. This seems to have been common practice until the IEEE Std 1003.1-1988 (“POSIX.1”) standard was re‐ leased. For best portability, modern implementations should fill the numeric fields with leading zeros. 1mPre-POSIX Archives0m An early draft of IEEE Std 1003.1-1988 (“POSIX.1”) served as the basis for John Gilmore's 1mpdtar 22mprogram and many system implementations from the late 1980s and early 1990s. These archives generally follow the POSIX ustar format described below with the following variations: 1m• 22mThe magic value consists of the five characters “ustar” fol‐ lowed by a space. The version field contains a space character followed by a null. 1m• 22mThe numeric fields are generally filled with leading spaces (not leading zeros as recommended in the final standard). 1m• 22mThe prefix field is often not used, limiting pathnames to the 100 characters of old-style archives. 1mPOSIX ustar Archives0m IEEE Std 1003.1-1988 (“POSIX.1”) defined a standard tar file format to be read and written by compliant implementations of 4mtar24m(1). This for‐ mat is often called the “ustar” format, after the magic value used in the header. (The name is an acronym for “Unix Standard TAR”.) It ex‐ tends the historic format with new fields: struct header_posix_ustar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char prefix[155]; char pad[12]; }; 4mtypeflag0m Type of entry. POSIX extended the earlier 4mlinkflag24m field with several new type values: “0” Regular file. NUL should be treated as a synonym, for compatibility purposes. “1” Hard link. “2” Symbolic link. “3” Character device node. “4” Block device node. “5” Directory. “6” FIFO node. “7” Reserved. Other A POSIX-compliant implementation must treat any unrec‐ ognized typeflag value as a regular file. In particu‐ lar, writers should ensure that all entries have a valid filename so that they can be restored by readers that do not support the corresponding extension. Up‐ percase letters "A" through "Z" are reserved for custom extensions. Note that sockets and whiteout entries are not archivable. It is worth noting that the 4msize24m field, in particular, has dif‐ ferent meanings depending on the type. For regular files, of course, it indicates the amount of data following the header. For directories, it may be used to indicate the total size of all files in the directory, for use by operating systems that pre-allocate directory space. For all other types, it should be set to zero by writers and ignored by readers. 4mmagic24m Contains the magic value “ustar” followed by a NUL byte to in‐ dicate that this is a POSIX standard archive. Full compliance requires the uname and gname fields be properly set. 4mversion0m Version. This should be “00” (two copies of the ASCII digit zero) for POSIX standard archives. 4muname24m, 4mgname0m User and group names, as null-terminated ASCII strings. These should be used in preference to the uid/gid values when they are set and the corresponding names exist on the system. 4mdevmajor24m, 4mdevminor0m Major and minor numbers for character device or block device entry. 4mname24m, 4mprefix0m If the pathname is too long to fit in the 100 bytes provided by the standard format, it can be split at any 4m/24m character with the first portion going into the prefix field. If the prefix field is not empty, the reader will prepend the prefix value and a 4m/24m character to the regular name field to obtain the full pathname. The standard does not require a trailing 4m/24m character on directory names, though most implementations still include this for compatibility reasons. Note that all unused bytes must be set to NUL. Field termination is specified slightly differently by POSIX than by previous implementations. The 4mmagic24m, 4muname24m, and 4mgname24m fields must have a trailing NUL. The 4mpathname24m, 4mlinkname24m, and 4mprefix24m fields must have a trailing NUL unless they fill the entire field. (In particular, it is possible to store a 256-character pathname if it happens to have a 4m/24m as the 156th character.) POSIX requires numeric fields to be zero-padded in the front, and requires them to be terminated with either space or NUL characters. Currently, most tar implementations comply with the ustar format, occa‐ sionally extending it by adding new fields to the blank area at the end of the header record. 1mNumeric Extensions0m There have been several attempts to extend the range of sizes or times supported by modifying how numbers are stored in the header. One obvious extension to increase the size of files is to eliminate the terminating characters from the various numeric fields. For example, the standard only allows the size field to contain 11 octal digits, re‐ serving the twelfth byte for a trailing NUL character. Allowing 12 oc‐ tal digits allows file sizes up to 64 GB. Another extension, utilized by GNU tar, star, and other newer 1mtar 22mim‐ plementations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first byte. The remain‐ der of the field is treated as a signed twos-complement value. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. In particular, this provides a consistent way to handle negative time values. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star program and the libarchive library support this exten‐ sion for all numeric fields. Note that this extension is largely obso‐ leted by the extended attribute record provided by the pax interchange format. Another early GNU extension allowed base-64 values rather than octal. This extension was short-lived and is no longer supported by any imple‐ mentation. 1mPax Interchange Format0m There are many attributes that cannot be portably stored in a POSIX us‐ tar archive. IEEE Std 1003.1-2001 (“POSIX.1”) defined a “pax interchange format” that uses two new types of entries to hold text- formatted metadata that applies to following entries. Note that a pax interchange format archive is a ustar archive in every respect. The new data is stored in ustar-compatible archive entries that use the “x” or “g” typeflag. In particular, older implementations that do not fully support these extensions will extract the metadata into regular files, where the metadata can be examined as necessary. An entry in a pax interchange format archive consists of one or two standard ustar entries, each with its own header and data. The first optional entry stores the extended attributes for the following entry. This optional first entry has an "x" typeflag and a size field that in‐ dicates the total size of the extended attributes. The extended at‐ tributes themselves are stored as a series of text-format lines encoded in the portable UTF-8 encoding. Each line consists of a decimal num‐ ber, a space, a key string, an equals sign, a value string, and a new line. The decimal number indicates the length of the entire line, in‐ cluding the initial length field and the trailing newline. An example of such a field is: 1m25 ctime=1084839148.1212\n0m Keys in all lowercase are standard keys. Vendors can add their own keys by prefixing them with an all uppercase vendor name and a period. Note that, unlike the historic header, numeric values are stored using decimal, not octal. A description of some common keys follows: 1matime22m, 1mctime22m, 1mmtime0m File access, inode change, and modification times. These fields can be negative or include a decimal point and a frac‐ tional value. 1mhdrcharset0m The character set used by the pax extension values. By de‐ fault, all textual values in the pax extended attributes are assumed to be in UTF-8, including pathnames, user names, and group names. In some cases, it is not possible to translate local conventions into UTF-8. If this key is present and the value is the six-character ASCII string “BINARY”, then all tex‐ tual values are assumed to be in a platform-dependent multi- byte encoding. Note that there are only two valid values for this key: “BINARY” or “ISO-IR 10646 2000 UTF-8”. No other val‐ ues are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particular, this flag should not be used as a general mechanism to allow filenames to be stored in arbitrary encodings. 1muname22m, 1muid22m, 1mgname22m, 1mgid0m User name, group name, and numeric UID and GID values. The user name and group name stored here are encoded in UTF8 and can thus include non-ASCII characters. The UID and GID fields can be of arbitrary length. 1mlinkpath0m The full path of the linked-to file. Note that this is encoded in UTF8 and can thus include non-ASCII characters. 1mpath 22mThe full pathname of the entry. Note that this is encoded in UTF8 and can thus include non-ASCII characters. 1mrealtime.*22m, 1msecurity.*0m These keys are reserved and may be used for future standardiza‐ tion. 1msize 22mThe size of the file. Note that there is no length limit on this field, allowing conforming archives to store files much larger than the historic 8GB limit. 1mSCHILY.*0m Vendor-specific attributes used by Joerg Schilling's 1mstar 22mim‐ plementation. 1mSCHILY.acl.access22m, 1mSCHILY.acl.default22m, 1mSCHILY.acl.ace0m Stores the access, default and NFSv4 ACLs as textual strings in a format that is an extension of the format specified by POSIX.1e draft 17. In particular, each user or group access specification can include an additional colon-separated field with the numeric UID or GID. This allows ACLs to be restored on systems that may not have complete user or group information available (such as when NIS/YP or LDAP services are temporarily unavailable). 1mSCHILY.devminor22m, 1mSCHILY.devmajor0m The full minor and major numbers for device nodes. 1mSCHILY.fflags0m The file flags. 1mSCHILY.realsize0m The full size of the file on disk. XXX explain? XXX 1mSCHILY.dev22m, 1mSCHILY.ino22m, 1mSCHILY.nlinks0m The device number, inode number, and link count for the entry. In particular, note that a pax interchange format archive using Joerg Schilling's 1mSCHILY.* 22mextensions can store all of the data from 4mstruct24m 4mstat24m. 1mLIBARCHIVE.*0m Vendor-specific attributes used by the 1mlibarchive 22mlibrary and programs that use it. 1mLIBARCHIVE.creationtime0m The time when the file was created. (This should not be con‐ fused with the POSIX “ctime” attribute, which refers to the time when the file metadata was last changed.) 1mLIBARCHIVE.xattr22m.4mnamespace24m.4mkey0m Libarchive stores POSIX.1e-style extended attributes using keys of this form. The 4mkey24m value is URL-encoded: All non-ASCII characters and the two special characters “=” and “%” are en‐ coded as “%” followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX 1mVENDOR.*0m XXX document other vendor-specific extensions XXX Any values stored in an extended attribute override the corresponding values in the regular tar header. Note that compliant readers should ignore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the standard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrarily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the stan‐ dard ustar header and use extended attributes whenever a text value contains non-ASCII characters. In addition to the 1mx 22mentry described above, the pax interchange format also supports a 1mg 22mentry. The 1mg 22mentry is identical in format, but spec‐ ifies attributes that serve as defaults for all subsequent archive en‐ tries. The 1mg 22mentry is not widely used. Besides the new 1mx 22mand 1mg 22mentries, the pax interchange format has a few other minor variations from the earlier ustar format. The most trou‐ bling one is that hardlinks are permitted to have data following them. This allows readers to restore any hardlink to a file without having to rewind the archive to find an earlier entry. However, it creates com‐ plications for robust readers, as it is no longer clear whether or not they should ignore the size field for hardlink entries. 1mGNU Tar Archives0m The GNU tar program started with a pre-POSIX format similar to that de‐ scribed earlier and has extended it using several different mechanisms: It added new fields to the empty space in the header (some of which was later used by POSIX for conflicting purposes); it allowed the header to be continued over multiple records; and it defined new entries that modify following entries (similar in principle to the 1mx 22mentry described above, but each GNU special entry is single-purpose, unlike the gen‐ eral-purpose 1mx 22mentry). As a result, GNU tar archives are not POSIX compatible, although more lenient POSIX-compliant readers can success‐ fully extract most GNU tar archives. struct header_gnu_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char atime[12]; char ctime[12]; char offset[12]; char longnames[4]; char unused[1]; struct { char offset[12]; char numbytes[12]; } sparse[4]; char isextended[1]; char realsize[12]; char pad[17]; }; 4mtypeflag0m GNU tar uses the following special entry types, in addition to those defined by POSIX: 7 GNU tar treats type "7" records identically to type "0" records, except on one obscure RTOS where they are used to indicate the pre-allocation of a contiguous file on disk. D This indicates a directory entry. Unlike the POSIX- standard "5" typeflag, the header is followed by data records listing the names of files in this directory. Each name is preceded by an ASCII "Y" if the file is stored in this archive or "N" if the file is not stored in this archive. Each name is terminated with a null, and an extra null marks the end of the name list. The purpose of this entry is to support incremental back‐ ups; a program restoring from such an archive may wish to delete files on disk that did not exist in the di‐ rectory when the archive was made. Note that the "D" typeflag specifically violates POSIX, which requires that unrecognized typeflags be restored as normal files. In this case, restoring the "D" entry as a file could interfere with subsequent creation of the like-named directory. K The data for this entry is a long linkname for the fol‐ lowing regular entry. L The data for this entry is a long pathname for the fol‐ lowing regular entry. M This is a continuation of the last file on the previous volume. GNU multi-volume archives guarantee that each volume begins with a valid entry header. To ensure this, a file may be split, with part stored at the end of one volume, and part stored at the beginning of the next volume. The "M" typeflag indicates that this en‐ try continues an existing file. Such entries can only occur as the first or second entry in an archive (the latter only if the first entry is a volume label). The 4msize24m field specifies the size of this entry. The 4moffset24m field at bytes 369-380 specifies the offset where this file fragment begins. The 4mrealsize24m field specifies the total size of the file (which must equal 4msize24m plus 4moffset24m). When extracting, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. N Type "N" records are no longer generated by GNU tar. They contained a list of files to be renamed or sym‐ linked after extraction; this was originally used to support long names. The contents of this record are a text description of the operations to be done, in the form “Rename %s to %s\n” or “Symlink %s to %s\n”; in either case, both filenames are escaped using K&R C syntax. Due to security concerns, "N" records are now generally ignored when reading archives. S This is a “sparse” regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such entries are required, the header is extended as necessary with “extra” header extensions (an older format that is no longer used), or “sparse” extensions. V The 4mname24m field should be interpreted as a tape/volume header name. This entry should generally be ignored on extraction. 4mmagic24m The magic field holds the five characters “ustar” followed by a space. Note that POSIX ustar archives have a trailing null. 4mversion0m The version field holds a space character followed by a null. Note that POSIX ustar archives use two copies of the ASCII digit “0”. 4matime24m, 4mctime0m The time the file was last accessed and the time of last change of file information, stored in octal as with 4mmtime24m. 4mlongnames0m This field is apparently no longer used. Sparse 4moffset24m 4m/24m 4mnumbytes0m Each such structure specifies a single fragment of a sparse file. The two fields store values as octal numbers. The frag‐ ments are each padded to a multiple of 512 bytes in the archive. On extraction, the list of fragments is collected from the header (including any extension headers), and the data is then read and written to the file at appropriate offsets. 4misextended0m If this is set to non-zero, the header will be followed by ad‐ ditional “sparse header” records. Each such record contains information about as many as 21 additional sparse blocks as shown here: struct gnu_sparse_header { struct { char offset[12]; char numbytes[12]; } sparse[21]; char isextended[1]; char padding[7]; }; 4mrealsize0m A binary representation of the file's complete size, with a much larger range than the POSIX file size. In particular, with 1mM 22mtype files, the current entry is only a portion of the file. In that case, the POSIX size field will indicate the size of this entry; the 4mrealsize24m field will indicate the total size of the file. 1mGNU tar pax archives0m GNU tar 1.14 (XXX check this XXX) and later will write pax interchange format archives when you specify the 1m--posix 22mflag. This format follows the pax interchange format closely, using some 1mSCHILY 22mtags and intro‐ ducing new keywords to store sparse file information. There have been three iterations of the sparse file support, referred to as “0.0”, “0.1”, and “1.0”. 1mGNU.sparse.numblocks22m, 1mGNU.sparse.offset22m, 1mGNU.sparse.numbytes22m, 1mGNU.sparse.size0m The “0.0” format used an initial 1mGNU.sparse.numblocks 22mattribute to indicate the number of blocks in the file, a pair of 1mGNU.sparse.offset 22mand 1mGNU.sparse.numbytes 22mto indicate the off‐ set and size of each block, and a single 1mGNU.sparse.size 22mto in‐ dicate the full size of the file. This is not the same as the size in the tar header because the latter value does not in‐ clude the size of any holes. This format required that the or‐ der of attributes be preserved and relied on readers accepting multiple appearances of the same attribute names, which is not officially permitted by the standards. 1mGNU.sparse.map0m The “0.1” format used a single attribute that stored a comma- separated list of decimal numbers. Each pair of numbers indi‐ cated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. 1mGNU.sparse.major22m, 1mGNU.sparse.minor22m, 1mGNU.sparse.name22m, 1mGNU.sparse.realsize0m The “1.0” format stores the sparse block map in one or more 512-byte blocks prepended to the file data in the entry body. The pax attributes indicate the existence of this map (via the 1mGNU.sparse.major 22mand 1mGNU.sparse.minor 22mfields) and the full size of the file. The 1mGNU.sparse.name 22mholds the true name of the file. To avoid confusion, the name stored in the regular tar header is a modified name so that extraction errors will be ap‐ parent to users. 1mSolaris Tar0m XXX More Details Needed XXX Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an “extended” format that is fundamentally similar to pax interchange for‐ mat, with the following differences: 1m• 22mExtended attributes are stored in an entry whose type is 1mX22m, not 1mx22m, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the 1mx0m entry. 1m• 22mAn additional 1mA 22mheader is used to store an ACL for the follow‐ ing regular entry. The body of this entry contains a seven- digit octal number followed by a zero byte, followed by the textual ACL description. The octal value is the number of ACL entries plus a constant that indicates the ACL type: 01000000 for POSIX.1e ACLs and 03000000 for NFSv4 ACLs. 1mAIX Tar0m XXX More details needed XXX AIX Tar uses a ustar-formatted header with the type 1mA 22mfor storing coded ACL information. Unlike the Solaris format, AIX tar writes this header after the regular file body to which it applies. The pathname in this header is either 1mNFS4 22mor 1mAIXC 22mto indicate the type of ACL stored. The actual ACL is stored in platform-specific binary format. 1mMac OS X Tar0m The tar distributed with Apple's Mac OS X stores most regular files as two separate files in the tar archive. The two files have the same name except that the first one has “._” prepended to the last path ele‐ ment. This special file stores an AppleDouble-encoded binary blob with additional metadata about the second file, including ACL, extended at‐ tributes, and resources. To recreate the original file on disk, each separate file can be extracted and the Mac OS X 1mcopyfile22m() function can be used to unpack the separate metadata file and apply it to th regular file. Conversely, the same function provides a “pack” option to encode the extended metadata from a file into a separate file whose contents can then be put into a tar archive. Note that the Apple extended attributes interact badly with long file‐ names. Since each file is stored with the full name, a separate set of extensions needs to be included in the archive for each one, doubling the overhead required for files with long names. 1mSummary of tar type codes0m The following list is a condensed summary of the type codes used in tar header records generated by different tar implementations. More de‐ tails about specific implementations can be found above: NUL Early tar programs stored a zero byte for regular files. 1m0 22mPOSIX standard type code for a regular file. 1m1 22mPOSIX standard type code for a hard link description. 1m2 22mPOSIX standard type code for a symbolic link description. 1m3 22mPOSIX standard type code for a character device node. 1m4 22mPOSIX standard type code for a block device node. 1m5 22mPOSIX standard type code for a directory. 1m6 22mPOSIX standard type code for a FIFO. 1m7 22mPOSIX reserved. 1m7 22mGNU tar used for pre-allocated files on some systems. 1mA 22mSolaris tar ACL description stored prior to a regular file header. 1mA 22mAIX tar ACL description stored after the file body. 1mD 22mGNU tar directory dump. 1mK 22mGNU tar long linkname for the following header. 1mL 22mGNU tar long pathname for the following header. 1mM 22mGNU tar multivolume marker, indicating the file is a continuation of a file from the previous volume. 1mN 22mGNU tar long filename support. Deprecated. 1mS 22mGNU tar sparse regular file. 1mV 22mGNU tar tape/volume header name. 1mX 22mSolaris tar general-purpose extension header. 1mg 22mPOSIX pax interchange format global extensions. 1mx 22mPOSIX pax interchange format per-file extensions. 1mSEE ALSO0m 4mar24m(1), 4mpax24m(1), 4mtar24m(1) 1mSTANDARDS0m The 1mtar 22mutility is no longer a part of POSIX or the Single Unix Stan‐ dard. It last appeared in Version 2 of the Single UNIX Specification (“SUSv2”). It has been supplanted in subsequent standards by 4mpax24m(1). The ustar format is currently part of the specification for the 4mpax24m(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (“POSIX.1”). 1mHISTORY0m A 1mtar 22mcommand appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the 1mtp 22mprogram from Fourth Edition Unix which in turn replaced the 1mtap 22mprogram from First Edition Unix. John Gilmore's 1mpdtar 22mpublic-domain implementation (circa 1987) was highly influential and formed the basis of 1mGNU tar 22m(circa 1988). Joerg Shilling's 1mstar 22marchiver is another open-source (CDDL) archiver (origi‐ nally developed circa 1985) which features complete support for pax in‐ terchange format. This documentation was written as part of the 1mlibarchive 22mand 1mbsdtar0m project by Tim Kientzle . Debian December 27, 2016 4mTAR24m(5) @ 1.8 log @libarchive: updated to 3.7.2 Libarchive 3.7.2 is a security, bugfix and feature release. Security fixes: Multiple vulnerabilities have been fixed in the PAX writer (1b4e0d0) Important bugfixes: bsdunzip(1) now correctly handles arguments following an -x after the zipfile New features: bsdunzip(1) now supports the "--version" flag 7-zip reader now translates Windows permissions into UNIX permissions uudecode filter in raw mode now supports file name and file mode zstd filter now supports the "long" write option Libarchive 3.7.1 is a security, feature and bugfix release. Security fixes: SEGV and stack buffer overflow in verbose mode of cpio Feature updates: bsdunzip updated to match latest upstream code Important bugfixes: miscellaneous functional bugfixes build fixes on multiple platforms Libarchive 3.7.0 is a feature and bugfix release. New features: bsdunzip: new tool ported from FreeBSD drop-in replacement for Info-ZIP unzip, not yet ported for Windows 7zip reader: support for Zstandard compression 7zip reader: support for ARM64 filter zstd filter: support for multi-frame zstd archives Other notable bugfixes and improvements: pax: fix year 2038 problem on platforms with 64-bit time_t Windows: Universal Windows Platform (UWP) fixes and improvements Windows: bcrypt usage fixes and improvements Windows: time function usage fixes and improvements @ text @d1 1 a1 1 TAR(5) BSD File Formats Manual TAR(5) d3 2 a4 2 NAME tar — format of tape archive files d6 673 a678 664 DESCRIPTION The tar archive format collects any number of files, directories, and other file system objects (symbolic links, device nodes, etc.) into a single stream of bytes. The format was originally designed to be used with tape drives that operate with fixed-size blocks, but is widely used as a general packaging mechanism. General Format A tar archive consists of a series of 512-byte records. Each file system object requires a header record which stores basic metadata (pathname, owner, permissions, etc.) and zero or more records containing any file data. The end of the archive is indicated by two records consisting en‐ tirely of zero bytes. For compatibility with tape drives that use fixed block sizes, programs that read or write tar files always read or write a fixed number of records with each I/O operation. These “blocks” are always a multiple of the record size. The maximum block size supported by early implementa‐ tions was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms “block” and “record” here are not entirely standard; this document fol‐ lows the convention established by John Gilmore in documenting pdtar.) Old-Style Archive Format The original tar archive format has been extended many times to include additional information that various implementors found necessary. This section describes the variant implemented by the tar command included in Version 7 AT&T UNIX, which seems to be the earliest widely-used version of the tar program. The header record for an old-style tar archive consists of the following: struct header_old_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char linkflag[1]; char linkname[100]; char pad[255]; }; All unused bytes in the header record are filled with nulls. name Pathname, stored as a null-terminated string. Early tar imple‐ mentations only stored regular files (including hardlinks to those files). One common early convention used a trailing "/" character to indicate a directory name, allowing directory per‐ missions and owner information to be archived and restored. mode File mode, stored as an octal number in ASCII. uid, gid User id and group id of owner, as octal numbers in ASCII. size Size of file, as octal number in ASCII. For regular files only, this indicates the amount of data that follows the header. In particular, this field was ignored by early tar implementations when extracting hardlinks. Modern writers should always store a zero length for hardlink entries. mtime Modification time of file, as an octal number in ASCII. This in‐ dicates the number of seconds since the start of the epoch, 00:00:00 UTC January 1, 1970. Note that negative values should be avoided here, as they are handled inconsistently. checksum Header checksum, stored as an octal number in ASCII. To compute the checksum, set the checksum field to all spaces, then sum all bytes in the header using unsigned arithmetic. This field should be stored as six octal digits followed by a null and a space character. Note that many early implementations of tar used signed arithmetic for the checksum field, which can cause inter‐ operability problems when transferring archives between systems. Modern robust readers compute the checksum both ways and accept the header if either computation matches. linkflag, linkname In order to preserve hardlinks and conserve tape, a file with multiple links is only written to the archive the first time it is encountered. The next time it is encountered, the linkflag is set to an ASCII ‘1’ and the linkname field holds the first name under which this file appears. (Note that regular files have a null value in the linkflag field.) Early tar implementations varied in how they terminated these fields. The tar command in Version 7 AT&T UNIX used the following conventions (this is also documented in early BSD manpages): the pathname must be null-terminated; the mode, uid, and gid fields must end in a space and a null byte; the size and mtime fields must end in a space; the checksum is terminated by a null and a space. Early implementations filled the nu‐ meric fields with leading spaces. This seems to have been common prac‐ tice until the IEEE Std 1003.1-1988 (“POSIX.1”) standard was released. For best portability, modern implementations should fill the numeric fields with leading zeros. Pre-POSIX Archives An early draft of IEEE Std 1003.1-1988 (“POSIX.1”) served as the basis for John Gilmore's pdtar program and many system implementations from the late 1980s and early 1990s. These archives generally follow the POSIX ustar format described below with the following variations: • The magic value consists of the five characters “ustar” followed by a space. The version field contains a space character fol‐ lowed by a null. • The numeric fields are generally filled with leading spaces (not leading zeros as recommended in the final standard). • The prefix field is often not used, limiting pathnames to the 100 characters of old-style archives. POSIX ustar Archives IEEE Std 1003.1-1988 (“POSIX.1”) defined a standard tar file format to be read and written by compliant implementations of tar(1). This format is often called the “ustar” format, after the magic value used in the header. (The name is an acronym for “Unix Standard TAR”.) It extends the historic format with new fields: struct header_posix_ustar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char prefix[155]; char pad[12]; }; typeflag Type of entry. POSIX extended the earlier linkflag field with several new type values: “0” Regular file. NUL should be treated as a synonym, for compatibility purposes. “1” Hard link. “2” Symbolic link. “3” Character device node. “4” Block device node. “5” Directory. “6” FIFO node. “7” Reserved. Other A POSIX-compliant implementation must treat any unrecog‐ nized typeflag value as a regular file. In particular, writers should ensure that all entries have a valid file‐ name so that they can be restored by readers that do not support the corresponding extension. Uppercase letters "A" through "Z" are reserved for custom extensions. Note that sockets and whiteout entries are not archivable. It is worth noting that the size field, in particular, has dif‐ ferent meanings depending on the type. For regular files, of course, it indicates the amount of data following the header. For directories, it may be used to indicate the total size of all files in the directory, for use by operating systems that pre-al‐ locate directory space. For all other types, it should be set to zero by writers and ignored by readers. magic Contains the magic value “ustar” followed by a NUL byte to indi‐ cate that this is a POSIX standard archive. Full compliance re‐ quires the uname and gname fields be properly set. version Version. This should be “00” (two copies of the ASCII digit zero) for POSIX standard archives. uname, gname User and group names, as null-terminated ASCII strings. These should be used in preference to the uid/gid values when they are set and the corresponding names exist on the system. devmajor, devminor Major and minor numbers for character device or block device en‐ try. name, prefix If the pathname is too long to fit in the 100 bytes provided by the standard format, it can be split at any / character with the first portion going into the prefix field. If the prefix field is not empty, the reader will prepend the prefix value and a / character to the regular name field to obtain the full pathname. The standard does not require a trailing / character on directory names, though most implementations still include this for compat‐ ibility reasons. Note that all unused bytes must be set to NUL. Field termination is specified slightly differently by POSIX than by pre‐ vious implementations. The magic, uname, and gname fields must have a trailing NUL. The pathname, linkname, and prefix fields must have a trailing NUL unless they fill the entire field. (In particular, it is possible to store a 256-character pathname if it happens to have a / as the 156th character.) POSIX requires numeric fields to be zero-padded in the front, and requires them to be terminated with either space or NUL characters. Currently, most tar implementations comply with the ustar format, occa‐ sionally extending it by adding new fields to the blank area at the end of the header record. Numeric Extensions There have been several attempts to extend the range of sizes or times supported by modifying how numbers are stored in the header. One obvious extension to increase the size of files is to eliminate the terminating characters from the various numeric fields. For example, the standard only allows the size field to contain 11 octal digits, reserving the twelfth byte for a trailing NUL character. Allowing 12 octal digits allows file sizes up to 64 GB. Another extension, utilized by GNU tar, star, and other newer tar imple‐ mentations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first byte. The remainder of the field is treated as a signed twos-complement value. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. In particular, this provides a consistent way to handle negative time values. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star pro‐ gram and the libarchive library support this extension for all numeric fields. Note that this extension is largely obsoleted by the extended attribute record provided by the pax interchange format. Another early GNU extension allowed base-64 values rather than octal. This extension was short-lived and is no longer supported by any imple‐ mentation. Pax Interchange Format There are many attributes that cannot be portably stored in a POSIX ustar archive. IEEE Std 1003.1-2001 (“POSIX.1”) defined a “pax interchange format” that uses two new types of entries to hold text-formatted meta‐ data that applies to following entries. Note that a pax interchange for‐ mat archive is a ustar archive in every respect. The new data is stored in ustar-compatible archive entries that use the “x” or “g” typeflag. In particular, older implementations that do not fully support these exten‐ sions will extract the metadata into regular files, where the metadata can be examined as necessary. An entry in a pax interchange format archive consists of one or two stan‐ dard ustar entries, each with its own header and data. The first op‐ tional entry stores the extended attributes for the following entry. This optional first entry has an "x" typeflag and a size field that indi‐ cates the total size of the extended attributes. The extended attributes themselves are stored as a series of text-format lines encoded in the portable UTF-8 encoding. Each line consists of a decimal number, a space, a key string, an equals sign, a value string, and a new line. The decimal number indicates the length of the entire line, including the initial length field and the trailing newline. An example of such a field is: 25 ctime=1084839148.1212\n Keys in all lowercase are standard keys. Vendors can add their own keys by prefixing them with an all uppercase vendor name and a period. Note that, unlike the historic header, numeric values are stored using deci‐ mal, not octal. A description of some common keys follows: atime, ctime, mtime File access, inode change, and modification times. These fields can be negative or include a decimal point and a fractional value. hdrcharset The character set used by the pax extension values. By default, all textual values in the pax extended attributes are assumed to be in UTF-8, including pathnames, user names, and group names. In some cases, it is not possible to translate local conventions into UTF-8. If this key is present and the value is the six- character ASCII string “BINARY”, then all textual values are as‐ sumed to be in a platform-dependent multi-byte encoding. Note that there are only two valid values for this key: “BINARY” or “ISO-IR 10646 2000 UTF-8”. No other values are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particular, this flag should not be used as a general mechanism to allow filenames to be stored in arbitrary encodings. uname, uid, gname, gid User name, group name, and numeric UID and GID values. The user name and group name stored here are encoded in UTF8 and can thus include non-ASCII characters. The UID and GID fields can be of arbitrary length. linkpath The full path of the linked-to file. Note that this is encoded in UTF8 and can thus include non-ASCII characters. path The full pathname of the entry. Note that this is encoded in UTF8 and can thus include non-ASCII characters. realtime.*, security.* These keys are reserved and may be used for future standardiza‐ tion. size The size of the file. Note that there is no length limit on this field, allowing conforming archives to store files much larger than the historic 8GB limit. SCHILY.* Vendor-specific attributes used by Joerg Schilling's star imple‐ mentation. SCHILY.acl.access, SCHILY.acl.default, SCHILY.acl.ace Stores the access, default and NFSv4 ACLs as textual strings in a format that is an extension of the format specified by POSIX.1e draft 17. In particular, each user or group access specification can include an additional colon-separated field with the numeric UID or GID. This allows ACLs to be restored on systems that may not have complete user or group information available (such as when NIS/YP or LDAP services are temporarily unavailable). SCHILY.devminor, SCHILY.devmajor The full minor and major numbers for device nodes. SCHILY.fflags The file flags. SCHILY.realsize The full size of the file on disk. XXX explain? XXX SCHILY.dev, SCHILY.ino, SCHILY.nlinks The device number, inode number, and link count for the entry. In particular, note that a pax interchange format archive using Joerg Schilling's SCHILY.* extensions can store all of the data from struct stat. LIBARCHIVE.* Vendor-specific attributes used by the libarchive library and programs that use it. LIBARCHIVE.creationtime The time when the file was created. (This should not be confused with the POSIX “ctime” attribute, which refers to the time when the file metadata was last changed.) LIBARCHIVE.xattr.namespace.key Libarchive stores POSIX.1e-style extended attributes using keys of this form. The key value is URL-encoded: All non-ASCII char‐ acters and the two special characters “=” and “%” are encoded as “%” followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX VENDOR.* XXX document other vendor-specific extensions XXX Any values stored in an extended attribute override the corresponding values in the regular tar header. Note that compliant readers should ig‐ nore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the stan‐ dard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrarily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the standard ustar header and use extended attributes whenever a text value contains non-ASCII characters. In addition to the x entry described above, the pax interchange format also supports a g entry. The g entry is identical in format, but speci‐ fies attributes that serve as defaults for all subsequent archive en‐ tries. The g entry is not widely used. Besides the new x and g entries, the pax interchange format has a few other minor variations from the earlier ustar format. The most troubling one is that hardlinks are permitted to have data following them. This allows readers to restore any hardlink to a file without having to rewind the archive to find an earlier entry. However, it creates complications for robust readers, as it is no longer clear whether or not they should ignore the size field for hardlink entries. GNU Tar Archives The GNU tar program started with a pre-POSIX format similar to that de‐ scribed earlier and has extended it using several different mechanisms: It added new fields to the empty space in the header (some of which was later used by POSIX for conflicting purposes); it allowed the header to be continued over multiple records; and it defined new entries that mod‐ ify following entries (similar in principle to the x entry described above, but each GNU special entry is single-purpose, unlike the general- purpose x entry). As a result, GNU tar archives are not POSIX compati‐ ble, although more lenient POSIX-compliant readers can successfully ex‐ tract most GNU tar archives. struct header_gnu_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char atime[12]; char ctime[12]; char offset[12]; char longnames[4]; char unused[1]; struct { char offset[12]; char numbytes[12]; } sparse[4]; char isextended[1]; char realsize[12]; char pad[17]; }; typeflag GNU tar uses the following special entry types, in addition to those defined by POSIX: 7 GNU tar treats type "7" records identically to type "0" records, except on one obscure RTOS where they are used to indicate the pre-allocation of a contiguous file on disk. D This indicates a directory entry. Unlike the POSIX-stan‐ dard "5" typeflag, the header is followed by data records listing the names of files in this directory. Each name is preceded by an ASCII "Y" if the file is stored in this archive or "N" if the file is not stored in this archive. Each name is terminated with a null, and an extra null marks the end of the name list. The purpose of this en‐ try is to support incremental backups; a program restor‐ ing from such an archive may wish to delete files on disk that did not exist in the directory when the archive was made. Note that the "D" typeflag specifically violates POSIX, which requires that unrecognized typeflags be restored as normal files. In this case, restoring the "D" entry as a file could interfere with subsequent creation of the like-named directory. K The data for this entry is a long linkname for the fol‐ lowing regular entry. L The data for this entry is a long pathname for the fol‐ lowing regular entry. M This is a continuation of the last file on the previous volume. GNU multi-volume archives guarantee that each volume begins with a valid entry header. To ensure this, a file may be split, with part stored at the end of one volume, and part stored at the beginning of the next vol‐ ume. The "M" typeflag indicates that this entry contin‐ ues an existing file. Such entries can only occur as the first or second entry in an archive (the latter only if the first entry is a volume label). The size field spec‐ ifies the size of this entry. The offset field at bytes 369-380 specifies the offset where this file fragment be‐ gins. The realsize field specifies the total size of the file (which must equal size plus offset). When extract‐ ing, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. N Type "N" records are no longer generated by GNU tar. They contained a list of files to be renamed or symlinked after extraction; this was originally used to support long names. The contents of this record are a text de‐ scription of the operations to be done, in the form “Rename %s to %s\n” or “Symlink %s to %s\n”; in either case, both filenames are escaped using K&R C syntax. Due to security concerns, "N" records are now generally ig‐ nored when reading archives. S This is a “sparse” regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such en‐ tries are required, the header is extended as necessary with “extra” header extensions (an older format that is no longer used), or “sparse” extensions. V The name field should be interpreted as a tape/volume header name. This entry should generally be ignored on extraction. magic The magic field holds the five characters “ustar” followed by a space. Note that POSIX ustar archives have a trailing null. version The version field holds a space character followed by a null. Note that POSIX ustar archives use two copies of the ASCII digit “0”. atime, ctime The time the file was last accessed and the time of last change of file information, stored in octal as with mtime. longnames This field is apparently no longer used. Sparse offset / numbytes Each such structure specifies a single fragment of a sparse file. The two fields store values as octal numbers. The fragments are each padded to a multiple of 512 bytes in the archive. On ex‐ traction, the list of fragments is collected from the header (in‐ cluding any extension headers), and the data is then read and written to the file at appropriate offsets. isextended If this is set to non-zero, the header will be followed by addi‐ tional “sparse header” records. Each such record contains infor‐ mation about as many as 21 additional sparse blocks as shown here: struct gnu_sparse_header { struct { char offset[12]; char numbytes[12]; } sparse[21]; char isextended[1]; char padding[7]; }; realsize A binary representation of the file's complete size, with a much larger range than the POSIX file size. In particular, with M type files, the current entry is only a portion of the file. In that case, the POSIX size field will indicate the size of this entry; the realsize field will indicate the total size of the file. GNU tar pax archives GNU tar 1.14 (XXX check this XXX) and later will write pax interchange format archives when you specify the --posix flag. This format follows the pax interchange format closely, using some SCHILY tags and introduc‐ ing new keywords to store sparse file information. There have been three iterations of the sparse file support, referred to as “0.0”, “0.1”, and “1.0”. GNU.sparse.numblocks, GNU.sparse.offset, GNU.sparse.numbytes, GNU.sparse.size The “0.0” format used an initial GNU.sparse.numblocks attribute to indicate the number of blocks in the file, a pair of GNU.sparse.offset and GNU.sparse.numbytes to indicate the offset and size of each block, and a single GNU.sparse.size to indicate the full size of the file. This is not the same as the size in the tar header because the latter value does not include the size of any holes. This format required that the order of attributes be preserved and relied on readers accepting multiple appearances of the same attribute names, which is not officially permitted by the standards. GNU.sparse.map The “0.1” format used a single attribute that stored a comma-sep‐ arated list of decimal numbers. Each pair of numbers indicated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. GNU.sparse.major, GNU.sparse.minor, GNU.sparse.name, GNU.sparse.realsize The “1.0” format stores the sparse block map in one or more 512-byte blocks prepended to the file data in the entry body. The pax attributes indicate the existence of this map (via the GNU.sparse.major and GNU.sparse.minor fields) and the full size of the file. The GNU.sparse.name holds the true name of the file. To avoid confusion, the name stored in the regular tar header is a modified name so that extraction errors will be ap‐ parent to users. Solaris Tar XXX More Details Needed XXX Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an “extended” format that is fundamentally similar to pax interchange format, with the following differences: • Extended attributes are stored in an entry whose type is X, not x, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the x en‐ try. • An additional A header is used to store an ACL for the following regular entry. The body of this entry contains a seven-digit oc‐ tal number followed by a zero byte, followed by the textual ACL description. The octal value is the number of ACL entries plus a constant that indicates the ACL type: 01000000 for POSIX.1e ACLs and 03000000 for NFSv4 ACLs. AIX Tar XXX More details needed XXX AIX Tar uses a ustar-formatted header with the type A for storing coded ACL information. Unlike the Solaris format, AIX tar writes this header after the regular file body to which it applies. The pathname in this header is either NFS4 or AIXC to indicate the type of ACL stored. The actual ACL is stored in platform-specific binary format. Mac OS X Tar The tar distributed with Apple's Mac OS X stores most regular files as two separate files in the tar archive. The two files have the same name except that the first one has “._” prepended to the last path element. This special file stores an AppleDouble-encoded binary blob with addi‐ tional metadata about the second file, including ACL, extended at‐ tributes, and resources. To recreate the original file on disk, each separate file can be extracted and the Mac OS X copyfile() function can be used to unpack the separate metadata file and apply it to th regular file. Conversely, the same function provides a “pack” option to encode the extended metadata from a file into a separate file whose contents can then be put into a tar archive. Note that the Apple extended attributes interact badly with long file‐ names. Since each file is stored with the full name, a separate set of extensions needs to be included in the archive for each one, doubling the overhead required for files with long names. Summary of tar type codes The following list is a condensed summary of the type codes used in tar header records generated by different tar implementations. More details about specific implementations can be found above: NUL Early tar programs stored a zero byte for regular files. 0 POSIX standard type code for a regular file. 1 POSIX standard type code for a hard link description. 2 POSIX standard type code for a symbolic link description. 3 POSIX standard type code for a character device node. 4 POSIX standard type code for a block device node. 5 POSIX standard type code for a directory. 6 POSIX standard type code for a FIFO. 7 POSIX reserved. 7 GNU tar used for pre-allocated files on some systems. A Solaris tar ACL description stored prior to a regular file header. A AIX tar ACL description stored after the file body. D GNU tar directory dump. K GNU tar long linkname for the following header. L GNU tar long pathname for the following header. M GNU tar multivolume marker, indicating the file is a continuation of a file from the previous volume. N GNU tar long filename support. Deprecated. S GNU tar sparse regular file. V GNU tar tape/volume header name. X Solaris tar general-purpose extension header. g POSIX pax interchange format global extensions. x POSIX pax interchange format per-file extensions. SEE ALSO ar(1), pax(1), tar(1) STANDARDS The tar utility is no longer a part of POSIX or the Single Unix Standard. It last appeared in Version 2 of the Single UNIX Specification (“SUSv2”). It has been supplanted in subsequent standards by pax(1). The ustar for‐ mat is currently part of the specification for the pax(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (“POSIX.1”). HISTORY A tar command appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the tp program from Fourth Edition Unix which in turn replaced the tap program from First Edition Unix. John Gilmore's pdtar public-domain implementation (circa 1987) was highly influential and formed the basis of GNU tar (circa 1988). Joerg Shilling's star archiver is another open-source (CDDL) archiver (originally developed circa 1985) which features complete support for pax interchange format. d680 2 a681 2 This documentation was written as part of the libarchive and bsdtar project by Tim Kientzle . d683 1 a683 1 BSD December 27, 2016 BSD @ 1.7 log @libarchive: Update to 3.4.3 Libarchive 3.4.3 is a feature and bugfix release. New features: support for pzstd compressed files (#1357) support for RHT.security.selinux tar extended attribute (#1348) Important bugfixes: various zstd fixes and improvements (#1342 #1352 #1359) child process handling fixes (#1372) Libarchive 3.4.2 is a feature and security release. New features: support for atomic file extraction (bsdtar -x --safe-writes) (#1289) support for mbed TLS (PolarSSL) (#1301) Important bugfixes: security fixes in RAR5 reader (#1280 #1326) compression buffer fix in XAR writer (#1317) fix uname and gname longer than 32 characters in PAX writer (#1319) fix segfault when archiving hard links in ISO9660 and XAR writers (#1325) fix support for extracting 7z archive entries with Delta filter (#987) Libarchive 3.4.1 is a feature and security release. New features: Unicode filename support for reading lha/lzh archives New pax write option "xattrhdr" Important bugfixes: security fixes in wide string processing (#1276 #1298) security fixes in RAR5 reader (#1212 #1217 #1296) security fixes and optimizations to write filter logic (#351) security fix related to use of readlink(2) (1dae5a5) sparse file handling fixes (#1218 #1260) Thanks to all contributors and bug reporters. Special thanks to Christos Zoulas (@@zoulasc) from NetBSD for the atomic file extraction feature. @ text @d4 1 a4 1 tar -- format of tape archive files d17 2 a18 2 data. The end of the archive is indicated by two records consisting entirely of zero bytes. d22 7 a28 8 records with each I/O operation. These ``blocks'' are always a multiple of the record size. The maximum block size supported by early implemen- tations was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms ``block'' and ``record'' here are not entirely standard; this docu- ment follows the convention established by John Gilmore in documenting pdtar.) d53 1 a53 1 name Pathname, stored as a null-terminated string. Early tar imple- d56 1 a56 1 character to indicate a directory name, allowing directory per- d65 1 a65 1 this indicates the amount of data that follows the header. In d67 1 a67 1 when extracting hardlinks. Modern writers should always store a d70 2 a71 2 mtime Modification time of file, as an octal number in ASCII. This indicates the number of seconds since the start of the epoch, d80 2 a81 2 character. Note that many early implementations of tar used signed arithmetic for the checksum field, which can cause inter- d90 1 a90 1 set to an ASCII '1' and the linkname field holds the first name d99 3 a101 3 terminated by a null and a space. Early implementations filled the numeric fields with leading spaces. This seems to have been common prac- tice until the IEEE Std 1003.1-1988 (``POSIX.1'') standard was released. d106 1 a106 1 An early draft of IEEE Std 1003.1-1988 (``POSIX.1'') served as the basis d110 4 a113 4 o The magic value consists of the five characters ``ustar'' fol- lowed by a space. The version field contains a space character followed by a null. o The numeric fields are generally filled with leading spaces (not d115 1 a115 1 o The prefix field is often not used, limiting pathnames to the 100 d119 4 a122 4 IEEE Std 1003.1-1988 (``POSIX.1'') defined a standard tar file format to be read and written by compliant implementations of tar(1). This format is often called the ``ustar'' format, after the magic value used in the header. (The name is an acronym for ``Unix Standard TAR''.) It extends d148 1 a148 1 ``0'' Regular file. NUL should be treated as a synonym, for d150 8 a157 8 ``1'' Hard link. ``2'' Symbolic link. ``3'' Character device node. ``4'' Block device node. ``5'' Directory. ``6'' FIFO node. ``7'' Reserved. Other A POSIX-compliant implementation must treat any unrecog- d159 1 a159 1 writers should ensure that all entries have a valid file- d164 1 a164 1 It is worth noting that the size field, in particular, has dif- d168 7 a174 7 files in the directory, for use by operating systems that pre- allocate directory space. For all other types, it should be set to zero by writers and ignored by readers. magic Contains the magic value ``ustar'' followed by a NUL byte to indicate that this is a POSIX standard archive. Full compliance requires the uname and gname fields be properly set. d177 1 a177 1 Version. This should be ``00'' (two copies of the ASCII digit d186 2 a187 2 Major and minor numbers for character device or block device entry. d192 1 a192 1 first portion going into the prefix field. If the prefix field d196 1 a196 1 names, though most implementations still include this for compat- d201 1 a201 1 Field termination is specified slightly differently by POSIX than by pre- d210 1 a210 1 Currently, most tar implementations comply with the ustar format, occa- d224 2 a225 2 Another extension, utilized by GNU tar, star, and other newer tar imple- mentations, permits binary numbers in the standard numeric fields. This d231 1 a231 1 the length, mtime, ctime, and atime fields. Joerg Schilling's star pro- d237 1 a237 1 This extension was short-lived and is no longer supported by any imple- d242 3 a244 3 archive. IEEE Std 1003.1-2001 (``POSIX.1'') defined a ``pax interchange format'' that uses two new types of entries to hold text-formatted meta- data that applies to following entries. Note that a pax interchange for- d246 9 a254 9 in ustar-compatible archive entries that use the ``x'' or ``g'' typeflag. In particular, older implementations that do not fully support these extensions will extract the metadata into regular files, where the meta- data can be examined as necessary. An entry in a pax interchange format archive consists of one or two stan- dard ustar entries, each with its own header and data. The first optional entry stores the extended attributes for the following entry. This optional first entry has an "x" typeflag and a size field that indi- d265 1 a265 1 that, unlike the historic header, numeric values are stored using deci- d269 1 a269 1 File access, inode change, and modification times. These fields d279 7 a285 7 character ASCII string ``BINARY'', then all textual values are assumed to be in a platform-dependent multi-byte encoding. Note that there are only two valid values for this key: ``BINARY'' or ``ISO-IR 10646 2000 UTF-8''. No other values are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particu- lar, this flag should not be used as a general mechanism to allow d302 1 a302 1 These keys are reserved and may be used for future standardiza- d310 1 a310 1 Vendor-specific attributes used by Joerg Schilling's star imple- d329 1 a329 1 The full size of the file on disk. XXX explain? XXX d343 1 a343 1 with the POSIX ``ctime'' attribute, which refers to the time when d348 5 a352 5 of this form. The key value is URL-encoded: All non-ASCII char- acters and the two special characters ``='' and ``%'' are encoded as ``%'' followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX d358 9 a366 9 values in the regular tar header. Note that compliant readers should ignore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the standard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrar- ily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the standard ustar header and use extended attributes whenever a text value contains non- ASCII characters. d369 3 a371 3 also supports a g entry. The g entry is identical in format, but speci- fies attributes that serve as defaults for all subsequent archive entries. The g entry is not widely used. d382 2 a383 2 The GNU tar program started with a pre-POSIX format similar to that described earlier and has extended it using several different mechanisms: d386 1 a386 1 be continued over multiple records; and it defined new entries that mod- d389 3 a391 3 purpose x entry). As a result, GNU tar archives are not POSIX compati- ble, although more lenient POSIX-compliant readers can successfully extract most GNU tar archives. d432 1 a432 1 D This indicates a directory entry. Unlike the POSIX-stan- d438 5 a442 5 marks the end of the name list. The purpose of this entry is to support incremental backups; a program restoring from such an archive may wish to delete files on disk that did not exist in the directory when the ar- chive was made. d450 1 a450 1 K The data for this entry is a long linkname for the fol- d453 1 a453 1 L The data for this entry is a long pathname for the fol- d460 2 a461 2 volume, and part stored at the beginning of the next vol- ume. The "M" typeflag indicates that this entry contin- d464 1 a464 1 the first entry is a volume label). The size field spec- d466 7 a472 7 369-380 specifies the offset where this file fragment begins. The realsize field specifies the total size of the file (which must equal size plus offset). When extracting, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. d477 13 a489 13 long names. The contents of this record are a text description of the operations to be done, in the form ``Rename %s to %s\n'' or ``Symlink %s to %s\n''; in either case, both filenames are escaped using K&R C syn- tax. Due to security concerns, "N" records are now gen- erally ignored when reading archives. S This is a ``sparse'' regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such entries are required, the header is extended as nec- essary with ``extra'' header extensions (an older format that is no longer used), or ``sparse'' extensions. d495 1 a495 1 magic The magic field holds the five characters ``ustar'' followed by a d501 1 a501 1 ``0''. d513 3 a515 3 each padded to a multiple of 512 bytes in the archive. On extraction, the list of fragments is collected from the header (including any extension headers), and the data is then read and d519 3 a521 3 If this is set to non-zero, the header will be followed by addi- tional ``sparse header'' records. Each such record contains information about as many as 21 additional sparse blocks as shown d529 2 a530 2 char isextended[1]; char padding[7]; d543 5 a547 5 format archives when you specify the --posix flag. This format follows the pax interchange format closely, using some SCHILY tags and introduc- ing new keywords to store sparse file information. There have been three iterations of the sparse file support, referred to as ``0.0'', ``0.1'', and ``1.0''. d551 1 a551 1 The ``0.0'' format used an initial GNU.sparse.numblocks attribute d555 1 a555 1 the full size of the file. This is not the same as the size in d563 6 a568 6 The ``0.1'' format used a single attribute that stored a comma- separated list of decimal numbers. Each pair of numbers indi- cated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. d571 1 a571 1 The ``1.0'' format stores the sparse block map in one or more d577 2 a578 2 header is a modified name so that extraction errors will be apparent to users. d583 4 a586 4 Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an ``extended'' format that is fundamentally similar to pax interchange for- mat, with the following differences: o Extended attributes are stored in an entry whose type is X, not d588 5 a592 5 this entry appears to be the same as detailed above for the x entry. o An additional A header is used to store an ACL for the following regular entry. The body of this entry contains a seven-digit octal number followed by a zero byte, followed by the textual ACL d609 4 a612 4 except that the first one has ``._'' prepended to the last path element. This special file stores an AppleDouble-encoded binary blob with addi- tional metadata about the second file, including ACL, extended attributes, and resources. To recreate the original file on disk, each d615 1 a615 1 file. Conversely, the same function provides a ``pack'' option to encode d619 1 a619 1 Note that the Apple extended attributes interact badly with long file- d626 1 a626 1 header records generated by different tar implementations. More details d657 4 a660 5 It last appeared in Version 2 of the Single UNIX Specification (``SUSv2''). It has been supplanted in subsequent standards by pax(1). The ustar format is currently part of the specification for the pax(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (``POSIX.1''). @ 1.6 log @Update for libarchive-3.4.0: - improvements for Android APK and JAR archives - better support for non-recursive list and extract - tar --exclude-vcs support - fixes for file attributes and flags handling - zipx support - rar 5.0 reader @ text @d4 1 a4 1 tar — format of tape archive files d17 2 a18 2 data. The end of the archive is indicated by two records consisting en‐ tirely of zero bytes. d22 8 a29 7 records with each I/O operation. These “blocks” are always a multiple of the record size. The maximum block size supported by early implementa‐ tions was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms “block” and “record” here are not entirely standard; this document fol‐ lows the convention established by John Gilmore in documenting pdtar.) d54 1 a54 1 name Pathname, stored as a null-terminated string. Early tar imple‐ d57 1 a57 1 character to indicate a directory name, allowing directory per‐ d71 2 a72 2 mtime Modification time of file, as an octal number in ASCII. This in‐ dicates the number of seconds since the start of the epoch, d82 1 a82 1 signed arithmetic for the checksum field, which can cause inter‐ d91 1 a91 1 set to an ASCII ‘1’ and the linkname field holds the first name d100 3 a102 3 terminated by a null and a space. Early implementations filled the nu‐ meric fields with leading spaces. This seems to have been common prac‐ tice until the IEEE Std 1003.1-1988 (“POSIX.1”) standard was released. d107 1 a107 1 An early draft of IEEE Std 1003.1-1988 (“POSIX.1”) served as the basis d111 4 a114 4 • The magic value consists of the five characters “ustar” followed by a space. The version field contains a space character fol‐ lowed by a null. • The numeric fields are generally filled with leading spaces (not d116 1 a116 1 • The prefix field is often not used, limiting pathnames to the 100 d120 4 a123 4 IEEE Std 1003.1-1988 (“POSIX.1”) defined a standard tar file format to be read and written by compliant implementations of tar(1). This format is often called the “ustar” format, after the magic value used in the header. (The name is an acronym for “Unix Standard TAR”.) It extends d149 1 a149 1 “0” Regular file. NUL should be treated as a synonym, for d151 8 a158 8 “1” Hard link. “2” Symbolic link. “3” Character device node. “4” Block device node. “5” Directory. “6” FIFO node. “7” Reserved. Other A POSIX-compliant implementation must treat any unrecog‐ d160 1 a160 1 writers should ensure that all entries have a valid file‐ d165 1 a165 1 It is worth noting that the size field, in particular, has dif‐ d169 7 a175 7 files in the directory, for use by operating systems that pre-al‐ locate directory space. For all other types, it should be set to zero by writers and ignored by readers. magic Contains the magic value “ustar” followed by a NUL byte to indi‐ cate that this is a POSIX standard archive. Full compliance re‐ quires the uname and gname fields be properly set. d178 1 a178 1 Version. This should be “00” (two copies of the ASCII digit d187 2 a188 2 Major and minor numbers for character device or block device en‐ try. d197 1 a197 1 names, though most implementations still include this for compat‐ d202 1 a202 1 Field termination is specified slightly differently by POSIX than by pre‐ d211 1 a211 1 Currently, most tar implementations comply with the ustar format, occa‐ d225 1 a225 1 Another extension, utilized by GNU tar, star, and other newer tar imple‐ d232 1 a232 1 the length, mtime, ctime, and atime fields. Joerg Schilling's star pro‐ d238 1 a238 1 This extension was short-lived and is no longer supported by any imple‐ d243 3 a245 3 archive. IEEE Std 1003.1-2001 (“POSIX.1”) defined a “pax interchange format” that uses two new types of entries to hold text-formatted meta‐ data that applies to following entries. Note that a pax interchange for‐ d247 9 a255 9 in ustar-compatible archive entries that use the “x” or “g” typeflag. In particular, older implementations that do not fully support these exten‐ sions will extract the metadata into regular files, where the metadata can be examined as necessary. An entry in a pax interchange format archive consists of one or two stan‐ dard ustar entries, each with its own header and data. The first op‐ tional entry stores the extended attributes for the following entry. This optional first entry has an "x" typeflag and a size field that indi‐ d266 1 a266 1 that, unlike the historic header, numeric values are stored using deci‐ d280 7 a286 7 character ASCII string “BINARY”, then all textual values are as‐ sumed to be in a platform-dependent multi-byte encoding. Note that there are only two valid values for this key: “BINARY” or “ISO-IR 10646 2000 UTF-8”. No other values are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particular, this flag should not be used as a general mechanism to allow d303 1 a303 1 These keys are reserved and may be used for future standardiza‐ d311 1 a311 1 Vendor-specific attributes used by Joerg Schilling's star imple‐ d344 1 a344 1 with the POSIX “ctime” attribute, which refers to the time when d349 5 a353 5 of this form. The key value is URL-encoded: All non-ASCII char‐ acters and the two special characters “=” and “%” are encoded as “%” followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX d359 9 a367 9 values in the regular tar header. Note that compliant readers should ig‐ nore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the stan‐ dard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrarily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the standard ustar header and use extended attributes whenever a text value contains non-ASCII characters. d370 3 a372 3 also supports a g entry. The g entry is identical in format, but speci‐ fies attributes that serve as defaults for all subsequent archive en‐ tries. The g entry is not widely used. d383 2 a384 2 The GNU tar program started with a pre-POSIX format similar to that de‐ scribed earlier and has extended it using several different mechanisms: d387 1 a387 1 be continued over multiple records; and it defined new entries that mod‐ d390 3 a392 3 purpose x entry). As a result, GNU tar archives are not POSIX compati‐ ble, although more lenient POSIX-compliant readers can successfully ex‐ tract most GNU tar archives. d433 1 a433 1 D This indicates a directory entry. Unlike the POSIX-stan‐ d439 5 a443 5 marks the end of the name list. The purpose of this en‐ try is to support incremental backups; a program restor‐ ing from such an archive may wish to delete files on disk that did not exist in the directory when the archive was made. d451 1 a451 1 K The data for this entry is a long linkname for the fol‐ d454 1 a454 1 L The data for this entry is a long pathname for the fol‐ d461 2 a462 2 volume, and part stored at the beginning of the next vol‐ ume. The "M" typeflag indicates that this entry contin‐ d465 1 a465 1 the first entry is a volume label). The size field spec‐ d467 7 a473 7 369-380 specifies the offset where this file fragment be‐ gins. The realsize field specifies the total size of the file (which must equal size plus offset). When extract‐ ing, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. d478 13 a490 13 long names. The contents of this record are a text de‐ scription of the operations to be done, in the form “Rename %s to %s\n” or “Symlink %s to %s\n”; in either case, both filenames are escaped using K&R C syntax. Due to security concerns, "N" records are now generally ig‐ nored when reading archives. S This is a “sparse” regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such en‐ tries are required, the header is extended as necessary with “extra” header extensions (an older format that is no longer used), or “sparse” extensions. d496 1 a496 1 magic The magic field holds the five characters “ustar” followed by a d502 1 a502 1 “0”. d514 3 a516 3 each padded to a multiple of 512 bytes in the archive. On ex‐ traction, the list of fragments is collected from the header (in‐ cluding any extension headers), and the data is then read and d520 3 a522 3 If this is set to non-zero, the header will be followed by addi‐ tional “sparse header” records. Each such record contains infor‐ mation about as many as 21 additional sparse blocks as shown d545 1 a545 1 the pax interchange format closely, using some SCHILY tags and introduc‐ d547 2 a548 2 iterations of the sparse file support, referred to as “0.0”, “0.1”, and “1.0”. d552 1 a552 1 The “0.0” format used an initial GNU.sparse.numblocks attribute d564 6 a569 6 The “0.1” format used a single attribute that stored a comma-sep‐ arated list of decimal numbers. Each pair of numbers indicated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. d572 1 a572 1 The “1.0” format stores the sparse block map in one or more d578 2 a579 2 header is a modified name so that extraction errors will be ap‐ parent to users. d584 4 a587 4 Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an “extended” format that is fundamentally similar to pax interchange format, with the following differences: • Extended attributes are stored in an entry whose type is X, not d589 5 a593 5 this entry appears to be the same as detailed above for the x en‐ try. • An additional A header is used to store an ACL for the following regular entry. The body of this entry contains a seven-digit oc‐ tal number followed by a zero byte, followed by the textual ACL d610 4 a613 4 except that the first one has “._” prepended to the last path element. This special file stores an AppleDouble-encoded binary blob with addi‐ tional metadata about the second file, including ACL, extended at‐ tributes, and resources. To recreate the original file on disk, each d616 1 a616 1 file. Conversely, the same function provides a “pack” option to encode d620 1 a620 1 Note that the Apple extended attributes interact badly with long file‐ d658 5 a662 4 It last appeared in Version 2 of the Single UNIX Specification (“SUSv2”). It has been supplanted in subsequent standards by pax(1). The ustar for‐ mat is currently part of the specification for the pax(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (“POSIX.1”). @ 1.5 log @Merge for libarchive-3.3.2. @ text @d17 2 a18 2 data. The end of the archive is indicated by two records consisting entirely of zero bytes. d70 2 a71 2 mtime Modification time of file, as an octal number in ASCII. This indicates the number of seconds since the start of the epoch, d99 2 a100 2 terminated by a null and a space. Early implementations filled the numeric fields with leading spaces. This seems to have been common prac‐ d110 1 a110 1 · The magic value consists of the five characters “ustar” followed d113 1 a113 1 · The numeric fields are generally filled with leading spaces (not d115 1 a115 1 · The prefix field is often not used, limiting pathnames to the 100 d168 3 a170 3 files in the directory, for use by operating systems that pre- allocate directory space. For all other types, it should be set to zero by writers and ignored by readers. d173 2 a174 2 cate that this is a POSIX standard archive. Full compliance requires the uname and gname fields be properly set. d186 2 a187 2 Major and minor numbers for character device or block device entry. d252 2 a253 2 dard ustar entries, each with its own header and data. The first optional entry stores the extended attributes for the following entry. d279 2 a280 2 character ASCII string “BINARY”, then all textual values are assumed to be in a platform-dependent multi-byte encoding. Note d358 9 a366 9 values in the regular tar header. Note that compliant readers should ignore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the standard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrar‐ ily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the standard ustar header and use extended attributes whenever a text value contains non- ASCII characters. d370 2 a371 2 fies attributes that serve as defaults for all subsequent archive entries. The g entry is not widely used. d382 2 a383 2 The GNU tar program started with a pre-POSIX format similar to that described earlier and has extended it using several different mechanisms: d390 2 a391 2 ble, although more lenient POSIX-compliant readers can successfully extract most GNU tar archives. d438 5 a442 5 marks the end of the name list. The purpose of this entry is to support incremental backups; a program restoring from such an archive may wish to delete files on disk that did not exist in the directory when the ar‐ chive was made. d466 7 a472 7 369-380 specifies the offset where this file fragment begins. The realsize field specifies the total size of the file (which must equal size plus offset). When extracting, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. d477 2 a478 2 long names. The contents of this record are a text description of the operations to be done, in the form d481 2 a482 2 to security concerns, "N" records are now generally ignored when reading archives. d486 2 a487 2 fragment offset/length pairs. If more than four such entries are required, the header is extended as necessary d513 3 a515 3 each padded to a multiple of 512 bytes in the archive. On extraction, the list of fragments is collected from the header (including any extension headers), and the data is then read and d577 2 a578 2 header is a modified name so that extraction errors will be apparent to users. d586 1 a586 1 · Extended attributes are stored in an entry whose type is X, not d588 5 a592 5 this entry appears to be the same as detailed above for the x entry. · An additional A header is used to store an ACL for the following regular entry. The body of this entry contains a seven-digit octal number followed by a zero byte, followed by the textual ACL d611 2 a612 2 tional metadata about the second file, including ACL, extended attributes, and resources. To recreate the original file on disk, each @ 1.4 log @Merge libarchive-3.3.1. @ text @d3 2 a4 2 1mNAME0m 1mtar 22m— format of tape archive files d6 2 a7 2 1mDESCRIPTION0m The 1mtar 22marchive format collects any number of files, directories, and d13 2 a14 2 1mGeneral Format0m A 1mtar 22marchive consists of a series of 512-byte records. Each file system d28 1 a28 1 lows the convention established by John Gilmore in documenting 1mpdtar22m.) d30 1 a30 1 1mOld-Style Archive Format0m d37 1 a37 1 The header record for an old-style 1mtar 22marchive consists of the following: d53 1 a53 1 4mname24m Pathname, stored as a null-terminated string. Early tar imple‐ d59 1 a59 1 4mmode24m File mode, stored as an octal number in ASCII. d61 1 a61 1 4muid24m, 4mgid0m d64 1 a64 1 4msize24m Size of file, as octal number in ASCII. For regular files only, d70 1 a70 1 4mmtime24m Modification time of file, as an octal number in ASCII. This d75 1 a75 1 4mchecksum0m d86 1 a86 1 4mlinkflag24m, 4mlinkname0m d89 2 a90 2 is encountered. The next time it is encountered, the 4mlinkflag24m is set to an ASCII ‘1’ and the 4mlinkname24m field holds the first name d92 1 a92 1 null value in the 4mlinkflag24m field.) d105 1 a105 1 1mPre-POSIX Archives0m d107 1 a107 1 for John Gilmore's 1mpdtar 22mprogram and many system implementations from the d110 1 a110 1 1m· 22mThe magic value consists of the five characters “ustar” followed d113 1 a113 1 1m· 22mThe numeric fields are generally filled with leading spaces (not d115 1 a115 1 1m· 22mThe prefix field is often not used, limiting pathnames to the 100 d118 1 a118 1 1mPOSIX ustar Archives0m d145 2 a146 2 4mtypeflag0m Type of entry. POSIX extended the earlier 4mlinkflag24m field with d164 1 a164 1 It is worth noting that the 4msize24m field, in particular, has dif‐ d172 1 a172 1 4mmagic24m Contains the magic value “ustar” followed by a NUL byte to indi‐ d176 1 a176 1 4mversion0m d180 1 a180 1 4muname24m, 4mgname0m d185 1 a185 1 4mdevmajor24m, 4mdevminor0m d189 1 a189 1 4mname24m, 4mprefix0m d191 1 a191 1 the standard format, it can be split at any 4m/24m character with the d193 1 a193 1 is not empty, the reader will prepend the prefix value and a 4m/0m d195 1 a195 1 The standard does not require a trailing 4m/24m character on directory d202 2 a203 2 vious implementations. The 4mmagic24m, 4muname24m, and 4mgname24m fields must have a trailing NUL. The 4mpathname24m, 4mlinkname24m, and 4mprefix24m fields must have a d205 1 a205 1 possible to store a 256-character pathname if it happens to have a 4m/24m as d214 1 a214 1 1mNumeric Extensions0m d224 1 a224 1 Another extension, utilized by GNU tar, star, and other newer 1mtar 22mimple‐ d240 1 a240 1 1mPax Interchange Format0m d268 1 a268 1 1matime22m, 1mctime22m, 1mmtime0m d273 1 a273 1 1mhdrcharset0m d288 1 a288 1 1muname22m, 1muid22m, 1mgname22m, 1mgid0m d294 1 a294 1 1mlinkpath0m d298 1 a298 1 1mpath 22mThe full pathname of the entry. Note that this is encoded in d301 1 a301 1 1mrealtime.*22m, 1msecurity.*0m d305 1 a305 1 1msize 22mThe size of the file. Note that there is no length limit on this d309 2 a310 2 1mSCHILY.*0m Vendor-specific attributes used by Joerg Schilling's 1mstar 22mimple‐ d313 1 a313 1 1mSCHILY.acl.access22m, 1mSCHILY.acl.default, SCHILY.acl.ace0m d322 1 a322 1 1mSCHILY.devminor22m, 1mSCHILY.devmajor0m d325 1 a325 1 1mSCHILY.fflags0m d328 1 a328 1 1mSCHILY.realsize0m d331 1 a331 1 1mSCHILY.dev, SCHILY.ino22m, 1mSCHILY.nlinks0m d334 2 a335 2 Joerg Schilling's 1mSCHILY.* 22mextensions can store all of the data from 4mstruct24m 4mstat24m. d337 2 a338 2 1mLIBARCHIVE.*0m Vendor-specific attributes used by the 1mlibarchive 22mlibrary and d341 1 a341 1 1mLIBARCHIVE.creationtime0m d346 1 a346 1 1mLIBARCHIVE.xattr.4m22mnamespace24m.4mkey0m d348 1 a348 1 of this form. The 4mkey24m value is URL-encoded: All non-ASCII char‐ d354 1 a354 1 1mVENDOR.*0m d368 2 a369 2 In addition to the 1mx 22mentry described above, the pax interchange format also supports a 1mg 22mentry. The 1mg 22mentry is identical in format, but speci‐ d371 1 a371 1 entries. The 1mg 22mentry is not widely used. d373 1 a373 1 Besides the new 1mx 22mand 1mg 22mentries, the pax interchange format has a few d381 1 a381 1 1mGNU Tar Archives0m d387 1 a387 1 ify following entries (similar in principle to the 1mx 22mentry described d389 1 a389 1 purpose 1mx 22mentry). As a result, GNU tar archives are not POSIX compati‐ d423 1 a423 1 4mtypeflag0m d464 2 a465 2 the first entry is a volume label). The 4msize24m field spec‐ ifies the size of this entry. The 4moffset24m field at bytes d467 2 a468 2 begins. The 4mrealsize24m field specifies the total size of the file (which must equal 4msize24m plus 4moffset24m). When d491 1 a491 1 V The 4mname24m field should be interpreted as a tape/volume d495 1 a495 1 4mmagic24m The magic field holds the five characters “ustar” followed by a d498 1 a498 1 4mversion0m d503 1 a503 1 4matime24m, 4mctime0m d505 1 a505 1 of file information, stored in octal as with 4mmtime24m. d507 1 a507 1 4mlongnames0m d510 1 a510 1 Sparse 4moffset24m 4m/24m 4mnumbytes0m d518 1 a518 1 4misextended0m d533 1 a533 1 4mrealsize0m d535 1 a535 1 larger range than the POSIX file size. In particular, with 1mM0m d538 1 a538 1 entry; the 4mrealsize24m field will indicate the total size of the d541 1 a541 1 1mGNU tar pax archives0m d543 2 a544 2 format archives when you specify the 1m--posix 22mflag. This format follows the pax interchange format closely, using some 1mSCHILY 22mtags and introduc‐ d549 3 a551 3 1mGNU.sparse.numblocks22m, 1mGNU.sparse.offset22m, 1mGNU.sparse.numbytes22m, 1mGNU.sparse.size0m The “0.0” format used an initial 1mGNU.sparse.numblocks 22mattribute d553 2 a554 2 1mGNU.sparse.offset 22mand 1mGNU.sparse.numbytes 22mto indicate the offset and size of each block, and a single 1mGNU.sparse.size 22mto indicate d562 1 a562 1 1mGNU.sparse.map0m d570 1 a570 1 1mGNU.sparse.major22m, 1mGNU.sparse.minor22m, 1mGNU.sparse.name22m, 1mGNU.sparse.realsize0m d574 2 a575 2 1mGNU.sparse.major 22mand 1mGNU.sparse.minor 22mfields) and the full size of the file. The 1mGNU.sparse.name 22mholds the true name of the d580 1 a580 1 1mSolaris Tar0m d586 3 a588 3 1m· 22mExtended attributes are stored in an entry whose type is 1mX22m, not 1mx22m, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the 1mx0m d590 1 a590 1 1m· 22mAn additional 1mA 22mheader is used to store an ACL for the following d597 1 a597 1 1mAIX Tar0m d600 1 a600 1 AIX Tar uses a ustar-formatted header with the type 1mA 22mfor storing coded d603 1 a603 1 header is either 1mNFS4 22mor 1mAIXC 22mto indicate the type of ACL stored. The d606 1 a606 1 1mMac OS X Tar0m d613 1 a613 1 separate file can be extracted and the Mac OS X 1mcopyfile22m() function can d624 1 a624 1 1mSummary of tar type codes0m d629 15 a643 15 1m0 22mPOSIX standard type code for a regular file. 1m1 22mPOSIX standard type code for a hard link description. 1m2 22mPOSIX standard type code for a symbolic link description. 1m3 22mPOSIX standard type code for a character device node. 1m4 22mPOSIX standard type code for a block device node. 1m5 22mPOSIX standard type code for a directory. 1m6 22mPOSIX standard type code for a FIFO. 1m7 22mPOSIX reserved. 1m7 22mGNU tar used for pre-allocated files on some systems. 1mA 22mSolaris tar ACL description stored prior to a regular file header. 1mA 22mAIX tar ACL description stored after the file body. 1mD 22mGNU tar directory dump. 1mK 22mGNU tar long linkname for the following header. 1mL 22mGNU tar long pathname for the following header. 1mM 22mGNU tar multivolume marker, indicating the file is a continuation of d645 6 a650 6 1mN 22mGNU tar long filename support. Deprecated. 1mS 22mGNU tar sparse regular file. 1mV 22mGNU tar tape/volume header name. 1mX 22mSolaris tar general-purpose extension header. 1mg 22mPOSIX pax interchange format global extensions. 1mx 22mPOSIX pax interchange format per-file extensions. d652 1 a652 1 1mSEE ALSO0m d655 2 a656 2 1mSTANDARDS0m The 1mtar 22mutility is no longer a part of POSIX or the Single Unix Standard. d662 6 a667 6 1mHISTORY0m A 1mtar 22mcommand appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the 1mtp 22mprogram from Fourth Edition Unix which in turn replaced the 1mtap 22mprogram from First Edition Unix. John Gilmore's 1mpdtar 22mpublic-domain implementation (circa 1987) was highly influential and formed the basis of 1mGNU tar 22m(circa 1988). Joerg Shilling's 1mstar0m d671 1 a671 1 This documentation was written as part of the 1mlibarchive 22mand 1mbsdtar0m @ 1.3 log @Update for libarchive 3.2.1. @ text @d3 2 a4 2 NAME tar — format of tape archive files d6 2 a7 2 DESCRIPTION The tar archive format collects any number of files, directories, and d13 2 a14 2 General Format A tar archive consists of a series of 512-byte records. Each file system d28 1 a28 1 lows the convention established by John Gilmore in documenting pdtar.) d30 1 a30 1 Old-Style Archive Format d37 1 a37 1 The header record for an old-style tar archive consists of the following: d53 1 a53 1 name Pathname, stored as a null-terminated string. Early tar imple‐ d59 1 a59 1 mode File mode, stored as an octal number in ASCII. d61 1 a61 1 uid, gid d64 1 a64 1 size Size of file, as octal number in ASCII. For regular files only, d70 1 a70 1 mtime Modification time of file, as an octal number in ASCII. This d75 1 a75 1 checksum d86 1 a86 1 linkflag, linkname d89 2 a90 2 is encountered. The next time it is encountered, the linkflag is set to an ASCII ‘1’ and the linkname field holds the first name d92 1 a92 1 null value in the linkflag field.) d105 1 a105 1 Pre-POSIX Archives d107 1 a107 1 for John Gilmore's pdtar program and many system implementations from the d110 1 a110 1 · The magic value consists of the five characters “ustar” followed d113 1 a113 1 · The numeric fields are generally filled with leading spaces (not d115 1 a115 1 · The prefix field is often not used, limiting pathnames to the 100 d118 1 a118 1 POSIX ustar Archives d145 2 a146 2 typeflag Type of entry. POSIX extended the earlier linkflag field with d164 1 a164 1 It is worth noting that the size field, in particular, has dif‐ d172 1 a172 1 magic Contains the magic value “ustar” followed by a NUL byte to indi‐ d176 1 a176 1 version d180 1 a180 1 uname, gname d185 1 a185 1 devmajor, devminor d189 1 a189 1 name, prefix d191 1 a191 1 the standard format, it can be split at any / character with the d193 1 a193 1 is not empty, the reader will prepend the prefix value and a / d195 1 a195 1 The standard does not require a trailing / character on directory d202 2 a203 2 vious implementations. The magic, uname, and gname fields must have a trailing NUL. The pathname, linkname, and prefix fields must have a d205 1 a205 1 possible to store a 256-character pathname if it happens to have a / as d214 1 a214 1 Numeric Extensions d224 1 a224 1 Another extension, utilized by GNU tar, star, and other newer tar imple‐ d240 1 a240 1 Pax Interchange Format d268 1 a268 1 atime, ctime, mtime d273 1 a273 1 hdrcharset d288 1 a288 1 uname, uid, gname, gid d294 1 a294 1 linkpath d298 1 a298 1 path The full pathname of the entry. Note that this is encoded in d301 1 a301 1 realtime.*, security.* d305 1 a305 1 size The size of the file. Note that there is no length limit on this d309 2 a310 2 SCHILY.* Vendor-specific attributes used by Joerg Schilling's star imple‐ d313 8 a320 8 SCHILY.acl.access, SCHILY.acl.default Stores the access and default ACLs as textual strings in a format that is an extension of the format specified by POSIX.1e draft 17. In particular, each user or group access specification can include a fourth colon-separated field with the numeric UID or GID. This allows ACLs to be restored on systems that may not have complete user or group information available (such as when NIS/YP or LDAP services are temporarily unavailable). d322 1 a322 1 SCHILY.devminor, SCHILY.devmajor d325 1 a325 1 SCHILY.fflags d328 1 a328 1 SCHILY.realsize d331 1 a331 1 SCHILY.dev, SCHILY.ino, SCHILY.nlinks d334 2 a335 2 Joerg Schilling's SCHILY.* extensions can store all of the data from struct stat. d337 2 a338 2 LIBARCHIVE.* Vendor-specific attributes used by the libarchive library and d341 1 a341 1 LIBARCHIVE.creationtime d346 1 a346 1 LIBARCHIVE.xattr.namespace.key d348 1 a348 1 of this form. The key value is URL-encoded: All non-ASCII char‐ d354 1 a354 1 VENDOR.* d368 2 a369 2 In addition to the x entry described above, the pax interchange format also supports a g entry. The g entry is identical in format, but speci‐ d371 1 a371 1 entries. The g entry is not widely used. d373 1 a373 1 Besides the new x and g entries, the pax interchange format has a few d381 1 a381 1 GNU Tar Archives d387 1 a387 1 ify following entries (similar in principle to the x entry described d389 1 a389 1 purpose x entry). As a result, GNU tar archives are not POSIX compati‐ d423 1 a423 1 typeflag d464 2 a465 2 the first entry is a volume label). The size field spec‐ ifies the size of this entry. The offset field at bytes d467 2 a468 2 begins. The realsize field specifies the total size of the file (which must equal size plus offset). When d491 1 a491 1 V The name field should be interpreted as a tape/volume d495 1 a495 1 magic The magic field holds the five characters “ustar” followed by a d498 1 a498 1 version d503 1 a503 1 atime, ctime d505 1 a505 1 of file information, stored in octal as with mtime. d507 1 a507 1 longnames d510 1 a510 1 Sparse offset / numbytes d518 1 a518 1 isextended d533 1 a533 1 realsize d535 1 a535 1 larger range than the POSIX file size. In particular, with M d538 1 a538 1 entry; the realsize field will indicate the total size of the d541 1 a541 1 GNU tar pax archives d543 2 a544 2 format archives when you specify the --posix flag. This format follows the pax interchange format closely, using some SCHILY tags and introduc‐ d549 3 a551 3 GNU.sparse.numblocks, GNU.sparse.offset, GNU.sparse.numbytes, GNU.sparse.size The “0.0” format used an initial GNU.sparse.numblocks attribute d553 2 a554 2 GNU.sparse.offset and GNU.sparse.numbytes to indicate the offset and size of each block, and a single GNU.sparse.size to indicate d562 1 a562 1 GNU.sparse.map d570 1 a570 1 GNU.sparse.major, GNU.sparse.minor, GNU.sparse.name, GNU.sparse.realsize d574 2 a575 2 GNU.sparse.major and GNU.sparse.minor fields) and the full size of the file. The GNU.sparse.name holds the true name of the d580 1 a580 1 Solaris Tar d586 3 a588 3 · Extended attributes are stored in an entry whose type is X, not x, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the x d590 1 a590 1 · An additional A header is used to store an ACL for the following d597 1 a597 1 AIX Tar d600 1 a600 1 AIX Tar uses a ustar-formatted header with the type A for storing coded d603 1 a603 1 header is either NFS4 or AIXC to indicate the type of ACL stored. The d606 1 a606 1 Mac OS X Tar d613 1 a613 1 separate file can be extracted and the Mac OS X copyfile() function can d624 1 a624 1 Summary of tar type codes d629 15 a643 15 0 POSIX standard type code for a regular file. 1 POSIX standard type code for a hard link description. 2 POSIX standard type code for a symbolic link description. 3 POSIX standard type code for a character device node. 4 POSIX standard type code for a block device node. 5 POSIX standard type code for a directory. 6 POSIX standard type code for a FIFO. 7 POSIX reserved. 7 GNU tar used for pre-allocated files on some systems. A Solaris tar ACL description stored prior to a regular file header. A AIX tar ACL description stored after the file body. D GNU tar directory dump. K GNU tar long linkname for the following header. L GNU tar long pathname for the following header. M GNU tar multivolume marker, indicating the file is a continuation of d645 6 a650 6 N GNU tar long filename support. Deprecated. S GNU tar sparse regular file. V GNU tar tape/volume header name. X Solaris tar general-purpose extension header. g POSIX pax interchange format global extensions. x POSIX pax interchange format per-file extensions. d652 1 a652 1 SEE ALSO d655 2 a656 2 STANDARDS The tar utility is no longer a part of POSIX or the Single Unix Standard. d662 6 a667 6 HISTORY A tar command appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the tp program from Fourth Edition Unix which in turn replaced the tap program from First Edition Unix. John Gilmore's pdtar public-domain implementation (circa 1987) was highly influential and formed the basis of GNU tar (circa 1988). Joerg Shilling's star d671 1 a671 1 This documentation was written as part of the libarchive and bsdtar d674 1 a674 1 BSD December 23, 2011 BSD @ 1.2 log @Changes 3.1.2: This is a maintenance update to fix issues with the new RAR seeking feature. This new release also contains fixes for build failures when building libarchive using Visual Studio 2012 and MinGW. @ text @d668 1 a668 1 archiver is another open-source (GPL) archiver (originally developed d672 1 a672 1 project by Tim Kientzle ⟨kientzle@@FreeBSD.org⟩. @ 1.1 log @Initial revision @ text @d1 1 a1 1 TAR(5) FreeBSD File Formats Manual TAR(5) d4 1 a4 1 tar -- format of tape archive files d22 7 a28 6 records with each I/O operation. These ``blocks'' are always a multiple of the record size. The most common block size--and the maximum sup- ported by historic implementations--is 10240 bytes or 20 records. (Note: the terms ``block'' and ``record'' here are not entirely standard; this document follows the convention established by John Gilmore in document- ing pdtar.) d34 2 a35 2 Version 7 AT&T UNIX, which is one of the earliest widely-used versions of the tar program. d53 1 a53 1 name Pathname, stored as a null-terminated string. Early tar imple- d56 1 a56 1 character to indicate a directory name, allowing directory per- d81 1 a81 1 signed arithmetic for the checksum field, which can cause inter- d90 1 a90 1 set to an ASCII `1' and the linkname field holds the first name d100 2 a101 2 numeric fields with leading spaces. This seems to have been common prac- tice until the IEEE Std 1003.1-1988 (``POSIX.1'') standard was released. d106 1 a106 1 An early draft of IEEE Std 1003.1-1988 (``POSIX.1'') served as the basis d110 4 a113 3 o The magic value is ``ustar '' (note the following space). The version field contains a space character followed by a null. o The numeric fields are generally filled with leading spaces (not d115 1 a115 1 o The prefix field is often not used, limiting pathnames to the 100 d119 4 a122 4 IEEE Std 1003.1-1988 (``POSIX.1'') defined a standard tar file format to be read and written by compliant implementations of tar(1). This format is often called the ``ustar'' format, after the magic value used in the header. (The name is an acronym for ``Unix Standard TAR''.) It extends d148 1 a148 1 ``0'' Regular file. NULL should be treated as a synonym, for d150 8 a157 8 ``1'' Hard link. ``2'' Symbolic link. ``3'' Character device node. ``4'' Block device node. ``5'' Directory. ``6'' FIFO node. ``7'' Reserved. Other A POSIX-compliant implementation must treat any unrecog- d159 1 a159 1 writers should ensure that all entries have a valid file- d164 1 a164 1 It is worth noting that the size field, in particular, has dif- d172 2 a173 2 magic Contains the magic value ``ustar'' followed by a NULL byte to indicate that this is a POSIX standard archive. Full compliance d177 1 a177 1 Version. This should be ``00'' (two copies of the ASCII digit d189 9 a197 6 prefix First part of pathname. If the pathname is too long to fit in the 100 bytes provided by the standard format, it can be split at any / character with the first portion going here. If the prefix field is not empty, the reader will prepend the prefix value and a / character to the regular name field to obtain the full path- name. d199 1 a199 1 Note that all unused bytes must be set to NULL. d201 1 a201 1 Field termination is specified slightly differently by POSIX than by pre- d203 2 a204 2 trailing NULL. The pathname, linkname, and prefix fields must have a trailing NULL unless they fill the entire field. (In particular, it is d207 1 a207 1 the front, and allows them to be terminated with either space or NULL d210 1 a210 1 Currently, most tar implementations comply with the ustar format, occa- d214 26 d242 3 a244 3 archive. IEEE Std 1003.1-2001 (``POSIX.1'') defined a ``pax interchange format'' that uses two new types of entries to hold text-formatted meta- data that applies to following entries. Note that a pax interchange for- d246 4 a249 4 in ustar-compatible archive entries that use the ``x'' or ``g'' typeflag. In particular, older implementations that do not fully support these extensions will extract the metadata into regular files, where the meta- data can be examined as necessary. d251 1 a251 1 An entry in a pax interchange format archive consists of one or two stan- d254 1 a254 1 This optional first entry has an "x" typeflag and a size field that indi- d265 1 a265 1 that, unlike the historic header, numeric values are stored using deci- d273 15 d302 1 a302 1 These keys are reserved and may be used for future standardiza- d310 1 a310 1 Vendor-specific attributes used by Joerg Schilling's star imple- d325 6 d337 9 d348 5 a352 5 of this form. The key value is URL-encoded: All non-ASCII char- acters and the two special characters ``='' and ``%'' are encoded as ``%'' followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX d362 1 a362 1 for any of these fields. In particular, numeric fields can be arbitrar- d369 1 a369 1 also supports a g entry. The g entry is identical in format, but speci- d386 1 a386 1 be continued over multiple records; and it defined new entries that mod- d389 1 a389 1 purpose x entry). As a result, GNU tar archives are not POSIX compati- d432 1 a432 1 D This indicates a directory entry. Unlike the POSIX-stan- d441 1 a441 1 on disk that did not exist in the directory when the ar- d450 1 a450 1 K The data for this entry is a long linkname for the fol- d453 1 a453 1 L The data for this entry is a long pathname for the fol- d460 2 a461 2 volume, and part stored at the beginning of the next vol- ume. The "M" typeflag indicates that this entry contin- d464 1 a464 1 the first entry is a volume label). The size field spec- d472 1 a472 3 equal to realsize. FreeBSD's version of GNU tar does not handle the corner case of an archive's being continued in the middle of a long name or other extension header. d479 11 a489 10 ``Rename %s to %s\n'' or ``Symlink %s to %s\n''; in either case, both filenames are escaped using K&R C syn- tax. S This is a ``sparse'' regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such entries are required, the header is extended as nec- essary with ``extra'' header extensions (an older format that is no longer used), or ``sparse'' extensions. d495 1 a495 1 magic The magic field holds the five characters ``ustar'' followed by a d501 1 a501 1 ``0''. d519 3 a521 3 If this is set to non-zero, the header will be followed by addi- tional ``sparse header'' records. Each such record contains information about as many as 21 additional sparse blocks as shown d541 39 d583 4 a586 4 Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an ``extended'' format that is fundamentally similar to pax interchange for- mat, with the following differences: o Extended attributes are stored in an entry whose type is X, not d590 1 a590 1 o An additional A entry is used to store an ACL for the following d592 59 a650 20 octal number (whose value is 01000000 plus the number of ACL entries) followed by a zero byte, followed by the textual ACL description. Other Extensions One common extension, utilized by GNU tar, star, and other newer tar implementations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first character. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star program supports this extension for all numeric fields. Note that this extension is largely obsoleted by the extended attribute record provided by the pax interchange format. Another early GNU extension allowed base-64 values rather than octal. This extension was short-lived and such archives are almost never seen. However, there is still code in GNU tar to support them; this code is responsible for a very cryptic warning message that is sometimes seen when GNU tar encounters a damaged archive. d657 4 a660 5 It last appeared in Version 2 of the Single UNIX Specification (``SUSv2''). It has been supplanted in subsequent standards by pax(1). The ustar format is currently part of the specification for the pax(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (``POSIX.1''). d667 6 a672 3 and formed the basis of GNU tar. Joerg Shilling's star archiver is another open-source (GPL) archiver (originally developed circa 1985) which features complete support for pax interchange format. d674 1 a674 1 FreeBSD 6.0 May 20, 2004 FreeBSD 6.0 @ 1.1.1.1 log @Import libarchive-2.4.0 @ text @@ 1.1.1.2 log @Import libarchive 2.8.0: - Infrastructure: - Allow command line tools as fallback for missing compression libraries. If compiled without gzip for example, gunzip will be used automatically. - Improved support for a number of platforms like high-resolution timestamps and Extended Attributes on various Unix systems - New convience interface for creating archives based on disk content, complement of the archive_write_disk interface. - Frontends: - bsdcpio ready for public consumption - hand-written date parser replaces the yacc code - Filter system: - Simplified read filter chains - Option support for filters - LZMA, XZ, uudecode handled - Format support: - Write support for mtree files based on file system or archive content - Basic read support for Joliet - Write support for zip files - Write support for shar archives, both text-only and binary-safe @ text @d1 1 a1 1 tar(5) FreeBSD File Formats Manual tar(5) d23 5 a27 7 of the record size. The maximum block size supported by early implemen- tations was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms ``block'' and ``record'' here are not entirely standard; this docu- ment follows the convention established by John Gilmore in documenting pdtar.) d33 2 a34 2 Version 7 AT&T UNIX, which seems to be the earliest widely-used version of the tar program. d146 1 a146 1 ``0'' Regular file. NUL should be treated as a synonym, for d170 1 a170 1 magic Contains the magic value ``ustar'' followed by a NUL byte to d187 6 a192 9 name, prefix If the pathname is too long to fit in the 100 bytes provided by the standard format, it can be split at any / character with the first portion going into the prefix field. If the prefix field is not empty, the reader will prepend the prefix value and a / character to the regular name field to obtain the full pathname. The standard does not require a trailing / character on directory names, though most implementations still include this for compat- ibility reasons. d194 1 a194 1 Note that all unused bytes must be set to NUL. d198 2 a199 2 trailing NUL. The pathname, linkname, and prefix fields must have a trailing NUL unless they fill the entire field. (In particular, it is d202 1 a202 1 the front, and requires them to be terminated with either space or NUL a278 6 SCHILY.fflags The file flags. SCHILY.realsize The full size of the file on disk. XXX explain? XXX d411 3 a413 1 equal to realsize. d422 1 a422 2 tax. Due to security concerns, "N" records are now gen- erally ignored when reading archives. a480 37 GNU tar pax archives GNU tar 1.14 (XXX check this XXX) and later will write pax interchange format archives when you specify the --posix flag. This format uses cus- tom keywords to store sparse file information. There have been three iterations of this support, referred to as ``0.0'', ``0.1'', and ``1.0''. GNU.sparse.numblocks, GNU.sparse.offset, GNU.sparse.numbytes, GNU.sparse.size The ``0.0'' format used an initial GNU.sparse.numblocks attribute to indicate the number of blocks in the file, a pair of GNU.sparse.offset and GNU.sparse.numbytes to indicate the offset and size of each block, and a single GNU.sparse.size to indicate the full size of the file. This is not the same as the size in the tar header because the latter value does not include the size of any holes. This format required that the order of attributes be preserved and relied on readers accepting multiple appearances of the same attribute names, which is not officially permitted by the standards. GNU.sparse.map The ``0.1'' format used a single attribute that stored a comma- separated list of decimal numbers. Each pair of numbers indi- cated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. GNU.sparse.major, GNU.sparse.minor, GNU.sparse.name, GNU.sparse.realsize The ``1.0'' format stores the sparse block map in one or more 512-byte blocks prepended to the file data in the entry body. The pax attributes indicate the existence of this map (via the GNU.sparse.major and GNU.sparse.minor fields) and the full size of the file. The GNU.sparse.name holds the true name of the file. To avoid confusion, the name stored in the regular tar header is a modified name so that extraction errors will be apparent to users. d493 3 a495 16 octal number followed by a zero byte, followed by the textual ACL description. The octal value is the number of ACL entries plus a constant that indicates the ACL type: 01000000 for POSIX.1e ACLs and 03000000 for NFSv4 ACLs. AIX Tar XXX More details needed XXX Mac OS X Tar The tar distributed with Apple's Mac OS X stores most regular files as two separate entries in the tar archive. The two entries have the same name except that the first one has ``._'' added to the beginning of the name. This first entry stores the ``resource fork'' with additional attributes for the file. The Mac OS X CopyFile() API is used to separate a file on disk into separate resource and data streams and to reassemble those separate streams when the file is restored to disk. d498 9 a506 15 One obvious extension to increase the size of files is to eliminate the terminating characters from the various numeric fields. For example, the standard only allows the size field to contain 11 octal digits, reserving the twelfth byte for a trailing NUL character. Allowing 12 octal digits allows file sizes up to 64 GB. Another extension, utilized by GNU tar, star, and other newer tar imple- mentations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first byte. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star program supports this extension for all numeric fields. Note that this extension is largely obsoleted by the extended attribute record provided by the pax interchange format. d509 4 a512 2 This extension was short-lived and is no longer supported by any imple- mentation. d530 3 a532 6 and formed the basis of GNU tar (circa 1988). Joerg Shilling's star archiver is another open-source (GPL) archiver (originally developed circa 1985) which features complete support for pax interchange format. This documentation was written as part of the libarchive and bsdtar project by Tim Kientzle . d534 1 a534 1 FreeBSD 8.0 December 27, 2009 FreeBSD 8.0 @ 1.1.1.3 log @libarchive-2.8.2: - Fix NULL deference for short self-extracting zip archives - Don't dereference symlinks on Linux when reading ACLs - Better detection of SHA2 support for old OpenSSL versions - Fix parsing of input files for bsdtar -T - Do not leak setup_xattr into the global namespace - Fix build when an older libarchive is already installed - Use O_BINARY opening files in bsdtar - Include missing archive_crc32.h - Correctly include iconv.h required by libxml2 @ text @d1 1 a1 1 tar(5) NetBSD File Formats Manual tar(5) d66 1 a66 1 this indicates the amount of data that follows the header. In d68 1 a68 1 when extracting hardlinks. Modern writers should always store a d81 1 a81 1 character. Note that many early implementations of tar used d111 1 a111 1 The magic value is ``ustar '' (note the following space). The d113 1 a113 1 The numeric fields are generally filled with leading spaces (not d115 1 a115 1 The prefix field is often not used, limiting pathnames to the 100 d192 1 a192 1 first portion going into the prefix field. If the prefix field d243 1 a243 1 File access, inode change, and modification times. These fields d288 1 a288 1 The full size of the file on disk. XXX explain? XXX d313 1 a313 1 ily large. All text fields are encoded in UTF8. Compliant writers d434 1 a434 1 S This is a ``sparse'' regular file. Sparse files are d479 2 a480 2 char isextended[1]; char padding[7]; d493 1 a493 1 format archives when you specify the --posix flag. This format uses cus- d503 1 a503 1 the full size of the file. This is not the same as the size in d512 1 a512 1 separated list of decimal numbers. Each pair of numbers indi- d534 1 a534 1 Extended attributes are stored in an entry whose type is X, not d538 1 a538 1 An additional A entry is used to store an ACL for the following d565 1 a565 1 mentations, permits binary numbers in the standard numeric fields. This d601 1 a601 1 NetBSD 5.0 December 27, 2009 NetBSD 5.0 @ 1.1.1.4 log @libarchive-2.8.3: Build fix for Linux @ text @d1 1 a1 1 tar(5) FreeBSD File Formats Manual tar(5) d66 1 a66 1 this indicates the amount of data that follows the header. In d68 1 a68 1 when extracting hardlinks. Modern writers should always store a d81 1 a81 1 character. Note that many early implementations of tar used d111 1 a111 1 o The magic value is ``ustar '' (note the following space). The d113 1 a113 1 o The numeric fields are generally filled with leading spaces (not d115 1 a115 1 o The prefix field is often not used, limiting pathnames to the 100 d192 1 a192 1 first portion going into the prefix field. If the prefix field d243 1 a243 1 File access, inode change, and modification times. These fields d288 1 a288 1 The full size of the file on disk. XXX explain? XXX d313 1 a313 1 ily large. All text fields are encoded in UTF8. Compliant writers d434 1 a434 1 S This is a ``sparse'' regular file. Sparse files are d479 2 a480 2 char isextended[1]; char padding[7]; d493 1 a493 1 format archives when you specify the --posix flag. This format uses cus- d503 1 a503 1 the full size of the file. This is not the same as the size in d512 1 a512 1 separated list of decimal numbers. Each pair of numbers indi- d534 1 a534 1 o Extended attributes are stored in an entry whose type is X, not d538 1 a538 1 o An additional A entry is used to store an ACL for the following d565 1 a565 1 mentations, permits binary numbers in the standard numeric fields. This d601 1 a601 1 FreeBSD 9.0 December 27, 2009 FreeBSD 9.0 @ 1.1.1.5 log @Import libarchive-2.8.4: - Improved reliability of hash function detection - Fix issues on ancient FreeBSD, QNX, ancient NetBSD and Minix @ text @d1 1 a1 1 tar(5) NetBSD File Formats Manual tar(5) d66 1 a66 1 this indicates the amount of data that follows the header. In d68 1 a68 1 when extracting hardlinks. Modern writers should always store a d81 1 a81 1 character. Note that many early implementations of tar used d111 1 a111 1 The magic value is ``ustar '' (note the following space). The d113 1 a113 1 The numeric fields are generally filled with leading spaces (not d115 1 a115 1 The prefix field is often not used, limiting pathnames to the 100 d192 1 a192 1 first portion going into the prefix field. If the prefix field d243 1 a243 1 File access, inode change, and modification times. These fields d288 1 a288 1 The full size of the file on disk. XXX explain? XXX d313 1 a313 1 ily large. All text fields are encoded in UTF8. Compliant writers d434 1 a434 1 S This is a ``sparse'' regular file. Sparse files are d479 2 a480 2 char isextended[1]; char padding[7]; d493 1 a493 1 format archives when you specify the --posix flag. This format uses cus- d503 1 a503 1 the full size of the file. This is not the same as the size in d512 1 a512 1 separated list of decimal numbers. Each pair of numbers indi- d534 1 a534 1 Extended attributes are stored in an entry whose type is X, not d538 1 a538 1 An additional A entry is used to store an ACL for the following d565 1 a565 1 mentations, permits binary numbers in the standard numeric fields. This d601 1 a601 1 NetBSD 5.0 December 27, 2009 NetBSD 5.0 @ 1.1.1.6 log @Import libarchive-3.2.1: - security fixes and other bugfixes - support for multhreading in xz 5.2+ @ text @d1 1 a1 1 TAR(5) BSD File Formats Manual TAR(5) d4 1 a4 1 tar — format of tape archive files d22 8 a29 7 records with each I/O operation. These “blocks” are always a multiple of the record size. The maximum block size supported by early implementa‐ tions was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms “block” and “record” here are not entirely standard; this document fol‐ lows the convention established by John Gilmore in documenting pdtar.) d54 1 a54 1 name Pathname, stored as a null-terminated string. Early tar imple‐ d57 1 a57 1 character to indicate a directory name, allowing directory per‐ d66 1 a66 1 this indicates the amount of data that follows the header. In d68 1 a68 1 when extracting hardlinks. Modern writers should always store a d81 2 a82 2 character. Note that many early implementations of tar used signed arithmetic for the checksum field, which can cause inter‐ d91 1 a91 1 set to an ASCII ‘1’ and the linkname field holds the first name d101 2 a102 2 numeric fields with leading spaces. This seems to have been common prac‐ tice until the IEEE Std 1003.1-1988 (“POSIX.1”) standard was released. d107 1 a107 1 An early draft of IEEE Std 1003.1-1988 (“POSIX.1”) served as the basis d111 3 a113 4 · The magic value consists of the five characters “ustar” followed by a space. The version field contains a space character fol‐ lowed by a null. · The numeric fields are generally filled with leading spaces (not d115 1 a115 1 · The prefix field is often not used, limiting pathnames to the 100 d119 4 a122 4 IEEE Std 1003.1-1988 (“POSIX.1”) defined a standard tar file format to be read and written by compliant implementations of tar(1). This format is often called the “ustar” format, after the magic value used in the header. (The name is an acronym for “Unix Standard TAR”.) It extends d148 1 a148 1 “0” Regular file. NUL should be treated as a synonym, for d150 8 a157 8 “1” Hard link. “2” Symbolic link. “3” Character device node. “4” Block device node. “5” Directory. “6” FIFO node. “7” Reserved. Other A POSIX-compliant implementation must treat any unrecog‐ d159 1 a159 1 writers should ensure that all entries have a valid file‐ d164 1 a164 1 It is worth noting that the size field, in particular, has dif‐ d172 2 a173 2 magic Contains the magic value “ustar” followed by a NUL byte to indi‐ cate that this is a POSIX standard archive. Full compliance d177 1 a177 1 Version. This should be “00” (two copies of the ASCII digit d192 1 a192 1 first portion going into the prefix field. If the prefix field d196 1 a196 1 names, though most implementations still include this for compat‐ d201 1 a201 1 Field termination is specified slightly differently by POSIX than by pre‐ d210 1 a210 1 Currently, most tar implementations comply with the ustar format, occa‐ a213 26 Numeric Extensions There have been several attempts to extend the range of sizes or times supported by modifying how numbers are stored in the header. One obvious extension to increase the size of files is to eliminate the terminating characters from the various numeric fields. For example, the standard only allows the size field to contain 11 octal digits, reserving the twelfth byte for a trailing NUL character. Allowing 12 octal digits allows file sizes up to 64 GB. Another extension, utilized by GNU tar, star, and other newer tar imple‐ mentations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first byte. The remainder of the field is treated as a signed twos-complement value. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. In particular, this provides a consistent way to handle negative time values. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star pro‐ gram and the libarchive library support this extension for all numeric fields. Note that this extension is largely obsoleted by the extended attribute record provided by the pax interchange format. Another early GNU extension allowed base-64 values rather than octal. This extension was short-lived and is no longer supported by any imple‐ mentation. d216 3 a218 3 archive. IEEE Std 1003.1-2001 (“POSIX.1”) defined a “pax interchange format” that uses two new types of entries to hold text-formatted meta‐ data that applies to following entries. Note that a pax interchange for‐ d220 4 a223 4 in ustar-compatible archive entries that use the “x” or “g” typeflag. In particular, older implementations that do not fully support these exten‐ sions will extract the metadata into regular files, where the metadata can be examined as necessary. d225 1 a225 1 An entry in a pax interchange format archive consists of one or two stan‐ d228 1 a228 1 This optional first entry has an "x" typeflag and a size field that indi‐ d239 1 a239 1 that, unlike the historic header, numeric values are stored using deci‐ d243 1 a243 1 File access, inode change, and modification times. These fields a246 15 hdrcharset The character set used by the pax extension values. By default, all textual values in the pax extended attributes are assumed to be in UTF-8, including pathnames, user names, and group names. In some cases, it is not possible to translate local conventions into UTF-8. If this key is present and the value is the six- character ASCII string “BINARY”, then all textual values are assumed to be in a platform-dependent multi-byte encoding. Note that there are only two valid values for this key: “BINARY” or “ISO-IR 10646 2000 UTF-8”. No other values are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particular, this flag should not be used as a general mechanism to allow filenames to be stored in arbitrary encodings. d261 1 a261 1 These keys are reserved and may be used for future standardiza‐ d269 1 a269 1 Vendor-specific attributes used by Joerg Schilling's star imple‐ d288 1 a288 1 The full size of the file on disk. XXX explain? XXX a295 9 LIBARCHIVE.* Vendor-specific attributes used by the libarchive library and programs that use it. LIBARCHIVE.creationtime The time when the file was created. (This should not be confused with the POSIX “ctime” attribute, which refers to the time when the file metadata was last changed.) d298 5 a302 5 of this form. The key value is URL-encoded: All non-ASCII char‐ acters and the two special characters “=” and “%” are encoded as “%” followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX d312 2 a313 2 for any of these fields. In particular, numeric fields can be arbitrar‐ ily large. All text fields are encoded in UTF8. Compliant writers d319 1 a319 1 also supports a g entry. The g entry is identical in format, but speci‐ d336 1 a336 1 be continued over multiple records; and it defined new entries that mod‐ d339 1 a339 1 purpose x entry). As a result, GNU tar archives are not POSIX compati‐ d382 1 a382 1 D This indicates a directory entry. Unlike the POSIX-stan‐ d391 1 a391 1 on disk that did not exist in the directory when the ar‐ d400 1 a400 1 K The data for this entry is a long linkname for the fol‐ d403 1 a403 1 L The data for this entry is a long pathname for the fol‐ d410 2 a411 2 volume, and part stored at the beginning of the next vol‐ ume. The "M" typeflag indicates that this entry contin‐ d414 1 a414 1 the first entry is a volume label). The size field spec‐ d429 11 a439 11 “Rename %s to %s\n” or “Symlink %s to %s\n”; in either case, both filenames are escaped using K&R C syntax. Due to security concerns, "N" records are now generally ignored when reading archives. S This is a “sparse” regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such entries are required, the header is extended as necessary with “extra” header extensions (an older format that is no longer used), or “sparse” extensions. d445 1 a445 1 magic The magic field holds the five characters “ustar” followed by a d451 1 a451 1 “0”. d469 3 a471 3 If this is set to non-zero, the header will be followed by addi‐ tional “sparse header” records. Each such record contains infor‐ mation about as many as 21 additional sparse blocks as shown d479 2 a480 2 char isextended[1]; char padding[7]; d493 3 a495 5 format archives when you specify the --posix flag. This format follows the pax interchange format closely, using some SCHILY tags and introduc‐ ing new keywords to store sparse file information. There have been three iterations of the sparse file support, referred to as “0.0”, “0.1”, and “1.0”. d499 1 a499 1 The “0.0” format used an initial GNU.sparse.numblocks attribute d503 1 a503 1 the full size of the file. This is not the same as the size in d511 6 a516 6 The “0.1” format used a single attribute that stored a comma-sep‐ arated list of decimal numbers. Each pair of numbers indicated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. d519 1 a519 1 The “1.0” format stores the sparse block map in one or more d531 4 a534 4 Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an “extended” format that is fundamentally similar to pax interchange format, with the following differences: · Extended attributes are stored in an entry whose type is X, not d538 1 a538 1 · An additional A header is used to store an ACL for the following a547 6 AIX Tar uses a ustar-formatted header with the type A for storing coded ACL information. Unlike the Solaris format, AIX tar writes this header after the regular file body to which it applies. The pathname in this header is either NFS4 or AIXC to indicate the type of ACL stored. The actual ACL is stored in platform-specific binary format. d550 27 a576 43 two separate files in the tar archive. The two files have the same name except that the first one has “._” prepended to the last path element. This special file stores an AppleDouble-encoded binary blob with addi‐ tional metadata about the second file, including ACL, extended attributes, and resources. To recreate the original file on disk, each separate file can be extracted and the Mac OS X copyfile() function can be used to unpack the separate metadata file and apply it to th regular file. Conversely, the same function provides a “pack” option to encode the extended metadata from a file into a separate file whose contents can then be put into a tar archive. Note that the Apple extended attributes interact badly with long file‐ names. Since each file is stored with the full name, a separate set of extensions needs to be included in the archive for each one, doubling the overhead required for files with long names. Summary of tar type codes The following list is a condensed summary of the type codes used in tar header records generated by different tar implementations. More details about specific implementations can be found above: NUL Early tar programs stored a zero byte for regular files. 0 POSIX standard type code for a regular file. 1 POSIX standard type code for a hard link description. 2 POSIX standard type code for a symbolic link description. 3 POSIX standard type code for a character device node. 4 POSIX standard type code for a block device node. 5 POSIX standard type code for a directory. 6 POSIX standard type code for a FIFO. 7 POSIX reserved. 7 GNU tar used for pre-allocated files on some systems. A Solaris tar ACL description stored prior to a regular file header. A AIX tar ACL description stored after the file body. D GNU tar directory dump. K GNU tar long linkname for the following header. L GNU tar long pathname for the following header. M GNU tar multivolume marker, indicating the file is a continuation of a file from the previous volume. N GNU tar long filename support. Deprecated. S GNU tar sparse regular file. V GNU tar tape/volume header name. X Solaris tar general-purpose extension header. g POSIX pax interchange format global extensions. x POSIX pax interchange format per-file extensions. d583 5 a587 4 It last appeared in Version 2 of the Single UNIX Specification (“SUSv2”). It has been supplanted in subsequent standards by pax(1). The ustar for‐ mat is currently part of the specification for the pax(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (“POSIX.1”). d595 1 a595 1 archiver is another open-source (CDDL) archiver (originally developed d601 1 a601 1 BSD December 23, 2011 BSD @ 1.1.1.7 log @Import libarchive-3.3.1. @ text @d3 2 a4 2 1mNAME0m 1mtar 22m— format of tape archive files d6 2 a7 2 1mDESCRIPTION0m The 1mtar 22marchive format collects any number of files, directories, and d13 2 a14 2 1mGeneral Format0m A 1mtar 22marchive consists of a series of 512-byte records. Each file system d28 1 a28 1 lows the convention established by John Gilmore in documenting 1mpdtar22m.) d30 1 a30 1 1mOld-Style Archive Format0m d37 1 a37 1 The header record for an old-style 1mtar 22marchive consists of the following: d53 1 a53 1 4mname24m Pathname, stored as a null-terminated string. Early tar imple‐ d59 1 a59 1 4mmode24m File mode, stored as an octal number in ASCII. d61 1 a61 1 4muid24m, 4mgid0m d64 1 a64 1 4msize24m Size of file, as octal number in ASCII. For regular files only, d70 1 a70 1 4mmtime24m Modification time of file, as an octal number in ASCII. This d75 1 a75 1 4mchecksum0m d86 1 a86 1 4mlinkflag24m, 4mlinkname0m d89 2 a90 2 is encountered. The next time it is encountered, the 4mlinkflag24m is set to an ASCII ‘1’ and the 4mlinkname24m field holds the first name d92 1 a92 1 null value in the 4mlinkflag24m field.) d105 1 a105 1 1mPre-POSIX Archives0m d107 1 a107 1 for John Gilmore's 1mpdtar 22mprogram and many system implementations from the d110 1 a110 1 1m· 22mThe magic value consists of the five characters “ustar” followed d113 1 a113 1 1m· 22mThe numeric fields are generally filled with leading spaces (not d115 1 a115 1 1m· 22mThe prefix field is often not used, limiting pathnames to the 100 d118 1 a118 1 1mPOSIX ustar Archives0m d145 2 a146 2 4mtypeflag0m Type of entry. POSIX extended the earlier 4mlinkflag24m field with d164 1 a164 1 It is worth noting that the 4msize24m field, in particular, has dif‐ d172 1 a172 1 4mmagic24m Contains the magic value “ustar” followed by a NUL byte to indi‐ d176 1 a176 1 4mversion0m d180 1 a180 1 4muname24m, 4mgname0m d185 1 a185 1 4mdevmajor24m, 4mdevminor0m d189 1 a189 1 4mname24m, 4mprefix0m d191 1 a191 1 the standard format, it can be split at any 4m/24m character with the d193 1 a193 1 is not empty, the reader will prepend the prefix value and a 4m/0m d195 1 a195 1 The standard does not require a trailing 4m/24m character on directory d202 2 a203 2 vious implementations. The 4mmagic24m, 4muname24m, and 4mgname24m fields must have a trailing NUL. The 4mpathname24m, 4mlinkname24m, and 4mprefix24m fields must have a d205 1 a205 1 possible to store a 256-character pathname if it happens to have a 4m/24m as d214 1 a214 1 1mNumeric Extensions0m d224 1 a224 1 Another extension, utilized by GNU tar, star, and other newer 1mtar 22mimple‐ d240 1 a240 1 1mPax Interchange Format0m d268 1 a268 1 1matime22m, 1mctime22m, 1mmtime0m d273 1 a273 1 1mhdrcharset0m d288 1 a288 1 1muname22m, 1muid22m, 1mgname22m, 1mgid0m d294 1 a294 1 1mlinkpath0m d298 1 a298 1 1mpath 22mThe full pathname of the entry. Note that this is encoded in d301 1 a301 1 1mrealtime.*22m, 1msecurity.*0m d305 1 a305 1 1msize 22mThe size of the file. Note that there is no length limit on this d309 2 a310 2 1mSCHILY.*0m Vendor-specific attributes used by Joerg Schilling's 1mstar 22mimple‐ d313 8 a320 8 1mSCHILY.acl.access22m, 1mSCHILY.acl.default, SCHILY.acl.ace0m Stores the access, default and NFSv4 ACLs as textual strings in a format that is an extension of the format specified by POSIX.1e draft 17. In particular, each user or group access specification can include an additional colon-separated field with the numeric UID or GID. This allows ACLs to be restored on systems that may not have complete user or group information available (such as when NIS/YP or LDAP services are temporarily unavailable). d322 1 a322 1 1mSCHILY.devminor22m, 1mSCHILY.devmajor0m d325 1 a325 1 1mSCHILY.fflags0m d328 1 a328 1 1mSCHILY.realsize0m d331 1 a331 1 1mSCHILY.dev, SCHILY.ino22m, 1mSCHILY.nlinks0m d334 2 a335 2 Joerg Schilling's 1mSCHILY.* 22mextensions can store all of the data from 4mstruct24m 4mstat24m. d337 2 a338 2 1mLIBARCHIVE.*0m Vendor-specific attributes used by the 1mlibarchive 22mlibrary and d341 1 a341 1 1mLIBARCHIVE.creationtime0m d346 1 a346 1 1mLIBARCHIVE.xattr.4m22mnamespace24m.4mkey0m d348 1 a348 1 of this form. The 4mkey24m value is URL-encoded: All non-ASCII char‐ d354 1 a354 1 1mVENDOR.*0m d368 2 a369 2 In addition to the 1mx 22mentry described above, the pax interchange format also supports a 1mg 22mentry. The 1mg 22mentry is identical in format, but speci‐ d371 1 a371 1 entries. The 1mg 22mentry is not widely used. d373 1 a373 1 Besides the new 1mx 22mand 1mg 22mentries, the pax interchange format has a few d381 1 a381 1 1mGNU Tar Archives0m d387 1 a387 1 ify following entries (similar in principle to the 1mx 22mentry described d389 1 a389 1 purpose 1mx 22mentry). As a result, GNU tar archives are not POSIX compati‐ d423 1 a423 1 4mtypeflag0m d464 2 a465 2 the first entry is a volume label). The 4msize24m field spec‐ ifies the size of this entry. The 4moffset24m field at bytes d467 2 a468 2 begins. The 4mrealsize24m field specifies the total size of the file (which must equal 4msize24m plus 4moffset24m). When d491 1 a491 1 V The 4mname24m field should be interpreted as a tape/volume d495 1 a495 1 4mmagic24m The magic field holds the five characters “ustar” followed by a d498 1 a498 1 4mversion0m d503 1 a503 1 4matime24m, 4mctime0m d505 1 a505 1 of file information, stored in octal as with 4mmtime24m. d507 1 a507 1 4mlongnames0m d510 1 a510 1 Sparse 4moffset24m 4m/24m 4mnumbytes0m d518 1 a518 1 4misextended0m d533 1 a533 1 4mrealsize0m d535 1 a535 1 larger range than the POSIX file size. In particular, with 1mM0m d538 1 a538 1 entry; the 4mrealsize24m field will indicate the total size of the d541 1 a541 1 1mGNU tar pax archives0m d543 2 a544 2 format archives when you specify the 1m--posix 22mflag. This format follows the pax interchange format closely, using some 1mSCHILY 22mtags and introduc‐ d549 3 a551 3 1mGNU.sparse.numblocks22m, 1mGNU.sparse.offset22m, 1mGNU.sparse.numbytes22m, 1mGNU.sparse.size0m The “0.0” format used an initial 1mGNU.sparse.numblocks 22mattribute d553 2 a554 2 1mGNU.sparse.offset 22mand 1mGNU.sparse.numbytes 22mto indicate the offset and size of each block, and a single 1mGNU.sparse.size 22mto indicate d562 1 a562 1 1mGNU.sparse.map0m d570 1 a570 1 1mGNU.sparse.major22m, 1mGNU.sparse.minor22m, 1mGNU.sparse.name22m, 1mGNU.sparse.realsize0m d574 2 a575 2 1mGNU.sparse.major 22mand 1mGNU.sparse.minor 22mfields) and the full size of the file. The 1mGNU.sparse.name 22mholds the true name of the d580 1 a580 1 1mSolaris Tar0m d586 3 a588 3 1m· 22mExtended attributes are stored in an entry whose type is 1mX22m, not 1mx22m, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the 1mx0m d590 1 a590 1 1m· 22mAn additional 1mA 22mheader is used to store an ACL for the following d597 1 a597 1 1mAIX Tar0m d600 1 a600 1 AIX Tar uses a ustar-formatted header with the type 1mA 22mfor storing coded d603 1 a603 1 header is either 1mNFS4 22mor 1mAIXC 22mto indicate the type of ACL stored. The d606 1 a606 1 1mMac OS X Tar0m d613 1 a613 1 separate file can be extracted and the Mac OS X 1mcopyfile22m() function can d624 1 a624 1 1mSummary of tar type codes0m d629 15 a643 15 1m0 22mPOSIX standard type code for a regular file. 1m1 22mPOSIX standard type code for a hard link description. 1m2 22mPOSIX standard type code for a symbolic link description. 1m3 22mPOSIX standard type code for a character device node. 1m4 22mPOSIX standard type code for a block device node. 1m5 22mPOSIX standard type code for a directory. 1m6 22mPOSIX standard type code for a FIFO. 1m7 22mPOSIX reserved. 1m7 22mGNU tar used for pre-allocated files on some systems. 1mA 22mSolaris tar ACL description stored prior to a regular file header. 1mA 22mAIX tar ACL description stored after the file body. 1mD 22mGNU tar directory dump. 1mK 22mGNU tar long linkname for the following header. 1mL 22mGNU tar long pathname for the following header. 1mM 22mGNU tar multivolume marker, indicating the file is a continuation of d645 6 a650 6 1mN 22mGNU tar long filename support. Deprecated. 1mS 22mGNU tar sparse regular file. 1mV 22mGNU tar tape/volume header name. 1mX 22mSolaris tar general-purpose extension header. 1mg 22mPOSIX pax interchange format global extensions. 1mx 22mPOSIX pax interchange format per-file extensions. d652 1 a652 1 1mSEE ALSO0m d655 2 a656 2 1mSTANDARDS0m The 1mtar 22mutility is no longer a part of POSIX or the Single Unix Standard. d662 6 a667 6 1mHISTORY0m A 1mtar 22mcommand appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the 1mtp 22mprogram from Fourth Edition Unix which in turn replaced the 1mtap 22mprogram from First Edition Unix. John Gilmore's 1mpdtar 22mpublic-domain implementation (circa 1987) was highly influential and formed the basis of 1mGNU tar 22m(circa 1988). Joerg Shilling's 1mstar0m d671 1 a671 1 This documentation was written as part of the 1mlibarchive 22mand 1mbsdtar0m d674 1 a674 1 BSD December 27, 2016 BSD @ 1.1.1.8 log @Import libarchive-3.3.2 + 9de5f3 + f9dacbf: - Support NFS4 ACLs on Linux - Bugfixes @ text @d3 2 a4 2 NAME tar — format of tape archive files d6 2 a7 2 DESCRIPTION The tar archive format collects any number of files, directories, and d13 2 a14 2 General Format A tar archive consists of a series of 512-byte records. Each file system d28 1 a28 1 lows the convention established by John Gilmore in documenting pdtar.) d30 1 a30 1 Old-Style Archive Format d37 1 a37 1 The header record for an old-style tar archive consists of the following: d53 1 a53 1 name Pathname, stored as a null-terminated string. Early tar imple‐ d59 1 a59 1 mode File mode, stored as an octal number in ASCII. d61 1 a61 1 uid, gid d64 1 a64 1 size Size of file, as octal number in ASCII. For regular files only, d70 1 a70 1 mtime Modification time of file, as an octal number in ASCII. This d75 1 a75 1 checksum d86 1 a86 1 linkflag, linkname d89 2 a90 2 is encountered. The next time it is encountered, the linkflag is set to an ASCII ‘1’ and the linkname field holds the first name d92 1 a92 1 null value in the linkflag field.) d105 1 a105 1 Pre-POSIX Archives d107 1 a107 1 for John Gilmore's pdtar program and many system implementations from the d110 1 a110 1 · The magic value consists of the five characters “ustar” followed d113 1 a113 1 · The numeric fields are generally filled with leading spaces (not d115 1 a115 1 · The prefix field is often not used, limiting pathnames to the 100 d118 1 a118 1 POSIX ustar Archives d145 2 a146 2 typeflag Type of entry. POSIX extended the earlier linkflag field with d164 1 a164 1 It is worth noting that the size field, in particular, has dif‐ d172 1 a172 1 magic Contains the magic value “ustar” followed by a NUL byte to indi‐ d176 1 a176 1 version d180 1 a180 1 uname, gname d185 1 a185 1 devmajor, devminor d189 1 a189 1 name, prefix d191 1 a191 1 the standard format, it can be split at any / character with the d193 1 a193 1 is not empty, the reader will prepend the prefix value and a / d195 1 a195 1 The standard does not require a trailing / character on directory d202 2 a203 2 vious implementations. The magic, uname, and gname fields must have a trailing NUL. The pathname, linkname, and prefix fields must have a d205 1 a205 1 possible to store a 256-character pathname if it happens to have a / as d214 1 a214 1 Numeric Extensions d224 1 a224 1 Another extension, utilized by GNU tar, star, and other newer tar imple‐ d240 1 a240 1 Pax Interchange Format d268 1 a268 1 atime, ctime, mtime d273 1 a273 1 hdrcharset d288 1 a288 1 uname, uid, gname, gid d294 1 a294 1 linkpath d298 1 a298 1 path The full pathname of the entry. Note that this is encoded in d301 1 a301 1 realtime.*, security.* d305 1 a305 1 size The size of the file. Note that there is no length limit on this d309 2 a310 2 SCHILY.* Vendor-specific attributes used by Joerg Schilling's star imple‐ d313 1 a313 1 SCHILY.acl.access, SCHILY.acl.default, SCHILY.acl.ace d322 1 a322 1 SCHILY.devminor, SCHILY.devmajor d325 1 a325 1 SCHILY.fflags d328 1 a328 1 SCHILY.realsize d331 1 a331 1 SCHILY.dev, SCHILY.ino, SCHILY.nlinks d334 2 a335 2 Joerg Schilling's SCHILY.* extensions can store all of the data from struct stat. d337 2 a338 2 LIBARCHIVE.* Vendor-specific attributes used by the libarchive library and d341 1 a341 1 LIBARCHIVE.creationtime d346 1 a346 1 LIBARCHIVE.xattr.namespace.key d348 1 a348 1 of this form. The key value is URL-encoded: All non-ASCII char‐ d354 1 a354 1 VENDOR.* d368 2 a369 2 In addition to the x entry described above, the pax interchange format also supports a g entry. The g entry is identical in format, but speci‐ d371 1 a371 1 entries. The g entry is not widely used. d373 1 a373 1 Besides the new x and g entries, the pax interchange format has a few d381 1 a381 1 GNU Tar Archives d387 1 a387 1 ify following entries (similar in principle to the x entry described d389 1 a389 1 purpose x entry). As a result, GNU tar archives are not POSIX compati‐ d423 1 a423 1 typeflag d464 2 a465 2 the first entry is a volume label). The size field spec‐ ifies the size of this entry. The offset field at bytes d467 2 a468 2 begins. The realsize field specifies the total size of the file (which must equal size plus offset). When d491 1 a491 1 V The name field should be interpreted as a tape/volume d495 1 a495 1 magic The magic field holds the five characters “ustar” followed by a d498 1 a498 1 version d503 1 a503 1 atime, ctime d505 1 a505 1 of file information, stored in octal as with mtime. d507 1 a507 1 longnames d510 1 a510 1 Sparse offset / numbytes d518 1 a518 1 isextended d533 1 a533 1 realsize d535 1 a535 1 larger range than the POSIX file size. In particular, with M d538 1 a538 1 entry; the realsize field will indicate the total size of the d541 1 a541 1 GNU tar pax archives d543 2 a544 2 format archives when you specify the --posix flag. This format follows the pax interchange format closely, using some SCHILY tags and introduc‐ d549 3 a551 3 GNU.sparse.numblocks, GNU.sparse.offset, GNU.sparse.numbytes, GNU.sparse.size The “0.0” format used an initial GNU.sparse.numblocks attribute d553 2 a554 2 GNU.sparse.offset and GNU.sparse.numbytes to indicate the offset and size of each block, and a single GNU.sparse.size to indicate d562 1 a562 1 GNU.sparse.map d570 1 a570 1 GNU.sparse.major, GNU.sparse.minor, GNU.sparse.name, GNU.sparse.realsize d574 2 a575 2 GNU.sparse.major and GNU.sparse.minor fields) and the full size of the file. The GNU.sparse.name holds the true name of the d580 1 a580 1 Solaris Tar d586 3 a588 3 · Extended attributes are stored in an entry whose type is X, not x, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the x d590 1 a590 1 · An additional A header is used to store an ACL for the following d597 1 a597 1 AIX Tar d600 1 a600 1 AIX Tar uses a ustar-formatted header with the type A for storing coded d603 1 a603 1 header is either NFS4 or AIXC to indicate the type of ACL stored. The d606 1 a606 1 Mac OS X Tar d613 1 a613 1 separate file can be extracted and the Mac OS X copyfile() function can d624 1 a624 1 Summary of tar type codes d629 15 a643 15 0 POSIX standard type code for a regular file. 1 POSIX standard type code for a hard link description. 2 POSIX standard type code for a symbolic link description. 3 POSIX standard type code for a character device node. 4 POSIX standard type code for a block device node. 5 POSIX standard type code for a directory. 6 POSIX standard type code for a FIFO. 7 POSIX reserved. 7 GNU tar used for pre-allocated files on some systems. A Solaris tar ACL description stored prior to a regular file header. A AIX tar ACL description stored after the file body. D GNU tar directory dump. K GNU tar long linkname for the following header. L GNU tar long pathname for the following header. M GNU tar multivolume marker, indicating the file is a continuation of d645 6 a650 6 N GNU tar long filename support. Deprecated. S GNU tar sparse regular file. V GNU tar tape/volume header name. X Solaris tar general-purpose extension header. g POSIX pax interchange format global extensions. x POSIX pax interchange format per-file extensions. d652 1 a652 1 SEE ALSO d655 2 a656 2 STANDARDS The tar utility is no longer a part of POSIX or the Single Unix Standard. d662 6 a667 6 HISTORY A tar command appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the tp program from Fourth Edition Unix which in turn replaced the tap program from First Edition Unix. John Gilmore's pdtar public-domain implementation (circa 1987) was highly influential and formed the basis of GNU tar (circa 1988). Joerg Shilling's star d671 1 a671 1 This documentation was written as part of the libarchive and bsdtar @ 1.1.1.9 log @Import libarchive 3.4.0 @ text @d17 2 a18 2 data. The end of the archive is indicated by two records consisting en‐ tirely of zero bytes. d70 2 a71 2 mtime Modification time of file, as an octal number in ASCII. This in‐ dicates the number of seconds since the start of the epoch, d99 2 a100 2 terminated by a null and a space. Early implementations filled the nu‐ meric fields with leading spaces. This seems to have been common prac‐ d110 1 a110 1 • The magic value consists of the five characters “ustar” followed d113 1 a113 1 • The numeric fields are generally filled with leading spaces (not d115 1 a115 1 • The prefix field is often not used, limiting pathnames to the 100 d168 3 a170 3 files in the directory, for use by operating systems that pre-al‐ locate directory space. For all other types, it should be set to zero by writers and ignored by readers. d173 2 a174 2 cate that this is a POSIX standard archive. Full compliance re‐ quires the uname and gname fields be properly set. d186 2 a187 2 Major and minor numbers for character device or block device en‐ try. d252 2 a253 2 dard ustar entries, each with its own header and data. The first op‐ tional entry stores the extended attributes for the following entry. d279 2 a280 2 character ASCII string “BINARY”, then all textual values are as‐ sumed to be in a platform-dependent multi-byte encoding. Note d358 9 a366 9 values in the regular tar header. Note that compliant readers should ig‐ nore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the stan‐ dard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrarily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the standard ustar header and use extended attributes whenever a text value contains non-ASCII characters. d370 2 a371 2 fies attributes that serve as defaults for all subsequent archive en‐ tries. The g entry is not widely used. d382 2 a383 2 The GNU tar program started with a pre-POSIX format similar to that de‐ scribed earlier and has extended it using several different mechanisms: d390 2 a391 2 ble, although more lenient POSIX-compliant readers can successfully ex‐ tract most GNU tar archives. d438 5 a442 5 marks the end of the name list. The purpose of this en‐ try is to support incremental backups; a program restor‐ ing from such an archive may wish to delete files on disk that did not exist in the directory when the archive was made. d466 7 a472 7 369-380 specifies the offset where this file fragment be‐ gins. The realsize field specifies the total size of the file (which must equal size plus offset). When extract‐ ing, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. d477 2 a478 2 long names. The contents of this record are a text de‐ scription of the operations to be done, in the form d481 2 a482 2 to security concerns, "N" records are now generally ig‐ nored when reading archives. d486 2 a487 2 fragment offset/length pairs. If more than four such en‐ tries are required, the header is extended as necessary d513 3 a515 3 each padded to a multiple of 512 bytes in the archive. On ex‐ traction, the list of fragments is collected from the header (in‐ cluding any extension headers), and the data is then read and d577 2 a578 2 header is a modified name so that extraction errors will be ap‐ parent to users. d586 1 a586 1 • Extended attributes are stored in an entry whose type is X, not d588 5 a592 5 this entry appears to be the same as detailed above for the x en‐ try. • An additional A header is used to store an ACL for the following regular entry. The body of this entry contains a seven-digit oc‐ tal number followed by a zero byte, followed by the textual ACL d611 2 a612 2 tional metadata about the second file, including ACL, extended at‐ tributes, and resources. To recreate the original file on disk, each @ 1.1.1.10 log @Import libarchive 3.7.2 @ text @d65 1 a65 1 this indicates the amount of data that follows the header. In d67 1 a67 1 when extracting hardlinks. Modern writers should always store a d80 1 a80 1 character. Note that many early implementations of tar used d122 1 a122 1 header. (The name is an acronym for “Unix Standard TAR”.) It extends d192 1 a192 1 first portion going into the prefix field. If the prefix field d225 1 a225 1 mentations, permits binary numbers in the standard numeric fields. This d269 1 a269 1 File access, inode change, and modification times. These fields d282 1 a282 1 “ISO-IR 10646 2000 UTF-8”. No other values are permitted by the d329 1 a329 1 The full size of the file on disk. XXX explain? XXX d529 2 a530 2 char isextended[1]; char padding[7]; d543 1 a543 1 format archives when you specify the --posix flag. This format follows d545 1 a545 1 ing new keywords to store sparse file information. There have been three d555 1 a555 1 the full size of the file. This is not the same as the size in d626 1 a626 1 header records generated by different tar implementations. More details d659 1 a659 1 mat is currently part of the specification for the pax(1) utility. The @ 1.1.1.11 log @libarchove: import version 3.7.7 @ text @d1 1 a1 1 4mTAR24m(5) File Formats Manual 4mTAR24m(5) d3 2 a4 2 1mNAME0m tar — format of tape archive files d6 664 a669 673 1mDESCRIPTION0m The 1mtar 22marchive format collects any number of files, directories, and other file system objects (symbolic links, device nodes, etc.) into a single stream of bytes. The format was originally designed to be used with tape drives that operate with fixed-size blocks, but is widely used as a general packaging mechanism. 1mGeneral Format0m A 1mtar 22marchive consists of a series of 512-byte records. Each file sys‐ tem object requires a header record which stores basic metadata (path‐ name, owner, permissions, etc.) and zero or more records containing any file data. The end of the archive is indicated by two records consist‐ ing entirely of zero bytes. For compatibility with tape drives that use fixed block sizes, programs that read or write tar files always read or write a fixed number of records with each I/O operation. These “blocks” are always a multiple of the record size. The maximum block size supported by early imple‐ mentations was 10240 bytes or 20 records. This is still the default for most implementations although block sizes of 1MiB (2048 records) or larger are commonly used with modern high-speed tape drives. (Note: the terms “block” and “record” here are not entirely standard; this document follows the convention established by John Gilmore in docu‐ menting 1mpdtar22m.) 1mOld-Style Archive Format0m The original tar archive format has been extended many times to include additional information that various implementors found necessary. This section describes the variant implemented by the tar command included in Version 7 AT&T UNIX, which seems to be the earliest widely-used ver‐ sion of the tar program. The header record for an old-style 1mtar 22marchive consists of the follow‐ ing: struct header_old_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char linkflag[1]; char linkname[100]; char pad[255]; }; All unused bytes in the header record are filled with nulls. 4mname24m Pathname, stored as a null-terminated string. Early tar imple‐ mentations only stored regular files (including hardlinks to those files). One common early convention used a trailing "/" character to indicate a directory name, allowing directory per‐ missions and owner information to be archived and restored. 4mmode24m File mode, stored as an octal number in ASCII. 4muid24m, 4mgid0m User id and group id of owner, as octal numbers in ASCII. 4msize24m Size of file, as octal number in ASCII. For regular files only, this indicates the amount of data that follows the header. In particular, this field was ignored by early tar im‐ plementations when extracting hardlinks. Modern writers should always store a zero length for hardlink entries. 4mmtime24m Modification time of file, as an octal number in ASCII. This indicates the number of seconds since the start of the epoch, 00:00:00 UTC January 1, 1970. Note that negative values should be avoided here, as they are handled inconsistently. 4mchecksum0m Header checksum, stored as an octal number in ASCII. To com‐ pute the checksum, set the checksum field to all spaces, then sum all bytes in the header using unsigned arithmetic. This field should be stored as six octal digits followed by a null and a space character. Note that many early implementations of tar used signed arithmetic for the checksum field, which can cause interoperability problems when transferring archives be‐ tween systems. Modern robust readers compute the checksum both ways and accept the header if either computation matches. 4mlinkflag24m, 4mlinkname0m In order to preserve hardlinks and conserve tape, a file with multiple links is only written to the archive the first time it is encountered. The next time it is encountered, the 4mlinkflag0m is set to an ASCII ‘1’ and the 4mlinkname24m field holds the first name under which this file appears. (Note that regular files have a null value in the 4mlinkflag24m field.) Early tar implementations varied in how they terminated these fields. The tar command in Version 7 AT&T UNIX used the following conventions (this is also documented in early BSD manpages): the pathname must be null-terminated; the mode, uid, and gid fields must end in a space and a null byte; the size and mtime fields must end in a space; the check‐ sum is terminated by a null and a space. Early implementations filled the numeric fields with leading spaces. This seems to have been common practice until the IEEE Std 1003.1-1988 (“POSIX.1”) standard was re‐ leased. For best portability, modern implementations should fill the numeric fields with leading zeros. 1mPre-POSIX Archives0m An early draft of IEEE Std 1003.1-1988 (“POSIX.1”) served as the basis for John Gilmore's 1mpdtar 22mprogram and many system implementations from the late 1980s and early 1990s. These archives generally follow the POSIX ustar format described below with the following variations: 1m• 22mThe magic value consists of the five characters “ustar” fol‐ lowed by a space. The version field contains a space character followed by a null. 1m• 22mThe numeric fields are generally filled with leading spaces (not leading zeros as recommended in the final standard). 1m• 22mThe prefix field is often not used, limiting pathnames to the 100 characters of old-style archives. 1mPOSIX ustar Archives0m IEEE Std 1003.1-1988 (“POSIX.1”) defined a standard tar file format to be read and written by compliant implementations of 4mtar24m(1). This for‐ mat is often called the “ustar” format, after the magic value used in the header. (The name is an acronym for “Unix Standard TAR”.) It ex‐ tends the historic format with new fields: struct header_posix_ustar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char prefix[155]; char pad[12]; }; 4mtypeflag0m Type of entry. POSIX extended the earlier 4mlinkflag24m field with several new type values: “0” Regular file. NUL should be treated as a synonym, for compatibility purposes. “1” Hard link. “2” Symbolic link. “3” Character device node. “4” Block device node. “5” Directory. “6” FIFO node. “7” Reserved. Other A POSIX-compliant implementation must treat any unrec‐ ognized typeflag value as a regular file. In particu‐ lar, writers should ensure that all entries have a valid filename so that they can be restored by readers that do not support the corresponding extension. Up‐ percase letters "A" through "Z" are reserved for custom extensions. Note that sockets and whiteout entries are not archivable. It is worth noting that the 4msize24m field, in particular, has dif‐ ferent meanings depending on the type. For regular files, of course, it indicates the amount of data following the header. For directories, it may be used to indicate the total size of all files in the directory, for use by operating systems that pre-allocate directory space. For all other types, it should be set to zero by writers and ignored by readers. 4mmagic24m Contains the magic value “ustar” followed by a NUL byte to in‐ dicate that this is a POSIX standard archive. Full compliance requires the uname and gname fields be properly set. 4mversion0m Version. This should be “00” (two copies of the ASCII digit zero) for POSIX standard archives. 4muname24m, 4mgname0m User and group names, as null-terminated ASCII strings. These should be used in preference to the uid/gid values when they are set and the corresponding names exist on the system. 4mdevmajor24m, 4mdevminor0m Major and minor numbers for character device or block device entry. 4mname24m, 4mprefix0m If the pathname is too long to fit in the 100 bytes provided by the standard format, it can be split at any 4m/24m character with the first portion going into the prefix field. If the prefix field is not empty, the reader will prepend the prefix value and a 4m/24m character to the regular name field to obtain the full pathname. The standard does not require a trailing 4m/24m character on directory names, though most implementations still include this for compatibility reasons. Note that all unused bytes must be set to NUL. Field termination is specified slightly differently by POSIX than by previous implementations. The 4mmagic24m, 4muname24m, and 4mgname24m fields must have a trailing NUL. The 4mpathname24m, 4mlinkname24m, and 4mprefix24m fields must have a trailing NUL unless they fill the entire field. (In particular, it is possible to store a 256-character pathname if it happens to have a 4m/24m as the 156th character.) POSIX requires numeric fields to be zero-padded in the front, and requires them to be terminated with either space or NUL characters. Currently, most tar implementations comply with the ustar format, occa‐ sionally extending it by adding new fields to the blank area at the end of the header record. 1mNumeric Extensions0m There have been several attempts to extend the range of sizes or times supported by modifying how numbers are stored in the header. One obvious extension to increase the size of files is to eliminate the terminating characters from the various numeric fields. For example, the standard only allows the size field to contain 11 octal digits, re‐ serving the twelfth byte for a trailing NUL character. Allowing 12 oc‐ tal digits allows file sizes up to 64 GB. Another extension, utilized by GNU tar, star, and other newer 1mtar 22mim‐ plementations, permits binary numbers in the standard numeric fields. This is flagged by setting the high bit of the first byte. The remain‐ der of the field is treated as a signed twos-complement value. This permits 95-bit values for the length and time fields and 63-bit values for the uid, gid, and device numbers. In particular, this provides a consistent way to handle negative time values. GNU tar supports this extension for the length, mtime, ctime, and atime fields. Joerg Schilling's star program and the libarchive library support this exten‐ sion for all numeric fields. Note that this extension is largely obso‐ leted by the extended attribute record provided by the pax interchange format. Another early GNU extension allowed base-64 values rather than octal. This extension was short-lived and is no longer supported by any imple‐ mentation. 1mPax Interchange Format0m There are many attributes that cannot be portably stored in a POSIX us‐ tar archive. IEEE Std 1003.1-2001 (“POSIX.1”) defined a “pax interchange format” that uses two new types of entries to hold text- formatted metadata that applies to following entries. Note that a pax interchange format archive is a ustar archive in every respect. The new data is stored in ustar-compatible archive entries that use the “x” or “g” typeflag. In particular, older implementations that do not fully support these extensions will extract the metadata into regular files, where the metadata can be examined as necessary. An entry in a pax interchange format archive consists of one or two standard ustar entries, each with its own header and data. The first optional entry stores the extended attributes for the following entry. This optional first entry has an "x" typeflag and a size field that in‐ dicates the total size of the extended attributes. The extended at‐ tributes themselves are stored as a series of text-format lines encoded in the portable UTF-8 encoding. Each line consists of a decimal num‐ ber, a space, a key string, an equals sign, a value string, and a new line. The decimal number indicates the length of the entire line, in‐ cluding the initial length field and the trailing newline. An example of such a field is: 1m25 ctime=1084839148.1212\n0m Keys in all lowercase are standard keys. Vendors can add their own keys by prefixing them with an all uppercase vendor name and a period. Note that, unlike the historic header, numeric values are stored using decimal, not octal. A description of some common keys follows: 1matime22m, 1mctime22m, 1mmtime0m File access, inode change, and modification times. These fields can be negative or include a decimal point and a frac‐ tional value. 1mhdrcharset0m The character set used by the pax extension values. By de‐ fault, all textual values in the pax extended attributes are assumed to be in UTF-8, including pathnames, user names, and group names. In some cases, it is not possible to translate local conventions into UTF-8. If this key is present and the value is the six-character ASCII string “BINARY”, then all tex‐ tual values are assumed to be in a platform-dependent multi- byte encoding. Note that there are only two valid values for this key: “BINARY” or “ISO-IR 10646 2000 UTF-8”. No other val‐ ues are permitted by the standard, and the latter value should generally not be used as it is the default when this key is not specified. In particular, this flag should not be used as a general mechanism to allow filenames to be stored in arbitrary encodings. 1muname22m, 1muid22m, 1mgname22m, 1mgid0m User name, group name, and numeric UID and GID values. The user name and group name stored here are encoded in UTF8 and can thus include non-ASCII characters. The UID and GID fields can be of arbitrary length. 1mlinkpath0m The full path of the linked-to file. Note that this is encoded in UTF8 and can thus include non-ASCII characters. 1mpath 22mThe full pathname of the entry. Note that this is encoded in UTF8 and can thus include non-ASCII characters. 1mrealtime.*22m, 1msecurity.*0m These keys are reserved and may be used for future standardiza‐ tion. 1msize 22mThe size of the file. Note that there is no length limit on this field, allowing conforming archives to store files much larger than the historic 8GB limit. 1mSCHILY.*0m Vendor-specific attributes used by Joerg Schilling's 1mstar 22mim‐ plementation. 1mSCHILY.acl.access22m, 1mSCHILY.acl.default22m, 1mSCHILY.acl.ace0m Stores the access, default and NFSv4 ACLs as textual strings in a format that is an extension of the format specified by POSIX.1e draft 17. In particular, each user or group access specification can include an additional colon-separated field with the numeric UID or GID. This allows ACLs to be restored on systems that may not have complete user or group information available (such as when NIS/YP or LDAP services are temporarily unavailable). 1mSCHILY.devminor22m, 1mSCHILY.devmajor0m The full minor and major numbers for device nodes. 1mSCHILY.fflags0m The file flags. 1mSCHILY.realsize0m The full size of the file on disk. XXX explain? XXX 1mSCHILY.dev22m, 1mSCHILY.ino22m, 1mSCHILY.nlinks0m The device number, inode number, and link count for the entry. In particular, note that a pax interchange format archive using Joerg Schilling's 1mSCHILY.* 22mextensions can store all of the data from 4mstruct24m 4mstat24m. 1mLIBARCHIVE.*0m Vendor-specific attributes used by the 1mlibarchive 22mlibrary and programs that use it. 1mLIBARCHIVE.creationtime0m The time when the file was created. (This should not be con‐ fused with the POSIX “ctime” attribute, which refers to the time when the file metadata was last changed.) 1mLIBARCHIVE.xattr22m.4mnamespace24m.4mkey0m Libarchive stores POSIX.1e-style extended attributes using keys of this form. The 4mkey24m value is URL-encoded: All non-ASCII characters and the two special characters “=” and “%” are en‐ coded as “%” followed by two uppercase hexadecimal digits. The value of this key is the extended attribute value encoded in base 64. XXX Detail the base-64 format here XXX 1mVENDOR.*0m XXX document other vendor-specific extensions XXX Any values stored in an extended attribute override the corresponding values in the regular tar header. Note that compliant readers should ignore the regular fields when they are overridden. This is important, as existing archivers are known to store non-compliant values in the standard header fields in this situation. There are no limits on length for any of these fields. In particular, numeric fields can be arbitrarily large. All text fields are encoded in UTF8. Compliant writers should store only portable 7-bit ASCII characters in the stan‐ dard ustar header and use extended attributes whenever a text value contains non-ASCII characters. In addition to the 1mx 22mentry described above, the pax interchange format also supports a 1mg 22mentry. The 1mg 22mentry is identical in format, but spec‐ ifies attributes that serve as defaults for all subsequent archive en‐ tries. The 1mg 22mentry is not widely used. Besides the new 1mx 22mand 1mg 22mentries, the pax interchange format has a few other minor variations from the earlier ustar format. The most trou‐ bling one is that hardlinks are permitted to have data following them. This allows readers to restore any hardlink to a file without having to rewind the archive to find an earlier entry. However, it creates com‐ plications for robust readers, as it is no longer clear whether or not they should ignore the size field for hardlink entries. 1mGNU Tar Archives0m The GNU tar program started with a pre-POSIX format similar to that de‐ scribed earlier and has extended it using several different mechanisms: It added new fields to the empty space in the header (some of which was later used by POSIX for conflicting purposes); it allowed the header to be continued over multiple records; and it defined new entries that modify following entries (similar in principle to the 1mx 22mentry described above, but each GNU special entry is single-purpose, unlike the gen‐ eral-purpose 1mx 22mentry). As a result, GNU tar archives are not POSIX compatible, although more lenient POSIX-compliant readers can success‐ fully extract most GNU tar archives. struct header_gnu_tar { char name[100]; char mode[8]; char uid[8]; char gid[8]; char size[12]; char mtime[12]; char checksum[8]; char typeflag[1]; char linkname[100]; char magic[6]; char version[2]; char uname[32]; char gname[32]; char devmajor[8]; char devminor[8]; char atime[12]; char ctime[12]; char offset[12]; char longnames[4]; char unused[1]; struct { char offset[12]; char numbytes[12]; } sparse[4]; char isextended[1]; char realsize[12]; char pad[17]; }; 4mtypeflag0m GNU tar uses the following special entry types, in addition to those defined by POSIX: 7 GNU tar treats type "7" records identically to type "0" records, except on one obscure RTOS where they are used to indicate the pre-allocation of a contiguous file on disk. D This indicates a directory entry. Unlike the POSIX- standard "5" typeflag, the header is followed by data records listing the names of files in this directory. Each name is preceded by an ASCII "Y" if the file is stored in this archive or "N" if the file is not stored in this archive. Each name is terminated with a null, and an extra null marks the end of the name list. The purpose of this entry is to support incremental back‐ ups; a program restoring from such an archive may wish to delete files on disk that did not exist in the di‐ rectory when the archive was made. Note that the "D" typeflag specifically violates POSIX, which requires that unrecognized typeflags be restored as normal files. In this case, restoring the "D" entry as a file could interfere with subsequent creation of the like-named directory. K The data for this entry is a long linkname for the fol‐ lowing regular entry. L The data for this entry is a long pathname for the fol‐ lowing regular entry. M This is a continuation of the last file on the previous volume. GNU multi-volume archives guarantee that each volume begins with a valid entry header. To ensure this, a file may be split, with part stored at the end of one volume, and part stored at the beginning of the next volume. The "M" typeflag indicates that this en‐ try continues an existing file. Such entries can only occur as the first or second entry in an archive (the latter only if the first entry is a volume label). The 4msize24m field specifies the size of this entry. The 4moffset24m field at bytes 369-380 specifies the offset where this file fragment begins. The 4mrealsize24m field specifies the total size of the file (which must equal 4msize24m plus 4moffset24m). When extracting, GNU tar checks that the header file name is the one it is expecting, that the header offset is in the correct sequence, and that the sum of offset and size is equal to realsize. N Type "N" records are no longer generated by GNU tar. They contained a list of files to be renamed or sym‐ linked after extraction; this was originally used to support long names. The contents of this record are a text description of the operations to be done, in the form “Rename %s to %s\n” or “Symlink %s to %s\n”; in either case, both filenames are escaped using K&R C syntax. Due to security concerns, "N" records are now generally ignored when reading archives. S This is a “sparse” regular file. Sparse files are stored as a series of fragments. The header contains a list of fragment offset/length pairs. If more than four such entries are required, the header is extended as necessary with “extra” header extensions (an older format that is no longer used), or “sparse” extensions. V The 4mname24m field should be interpreted as a tape/volume header name. This entry should generally be ignored on extraction. 4mmagic24m The magic field holds the five characters “ustar” followed by a space. Note that POSIX ustar archives have a trailing null. 4mversion0m The version field holds a space character followed by a null. Note that POSIX ustar archives use two copies of the ASCII digit “0”. 4matime24m, 4mctime0m The time the file was last accessed and the time of last change of file information, stored in octal as with 4mmtime24m. 4mlongnames0m This field is apparently no longer used. Sparse 4moffset24m 4m/24m 4mnumbytes0m Each such structure specifies a single fragment of a sparse file. The two fields store values as octal numbers. The frag‐ ments are each padded to a multiple of 512 bytes in the archive. On extraction, the list of fragments is collected from the header (including any extension headers), and the data is then read and written to the file at appropriate offsets. 4misextended0m If this is set to non-zero, the header will be followed by ad‐ ditional “sparse header” records. Each such record contains information about as many as 21 additional sparse blocks as shown here: struct gnu_sparse_header { struct { char offset[12]; char numbytes[12]; } sparse[21]; char isextended[1]; char padding[7]; }; 4mrealsize0m A binary representation of the file's complete size, with a much larger range than the POSIX file size. In particular, with 1mM 22mtype files, the current entry is only a portion of the file. In that case, the POSIX size field will indicate the size of this entry; the 4mrealsize24m field will indicate the total size of the file. 1mGNU tar pax archives0m GNU tar 1.14 (XXX check this XXX) and later will write pax interchange format archives when you specify the 1m--posix 22mflag. This format follows the pax interchange format closely, using some 1mSCHILY 22mtags and intro‐ ducing new keywords to store sparse file information. There have been three iterations of the sparse file support, referred to as “0.0”, “0.1”, and “1.0”. 1mGNU.sparse.numblocks22m, 1mGNU.sparse.offset22m, 1mGNU.sparse.numbytes22m, 1mGNU.sparse.size0m The “0.0” format used an initial 1mGNU.sparse.numblocks 22mattribute to indicate the number of blocks in the file, a pair of 1mGNU.sparse.offset 22mand 1mGNU.sparse.numbytes 22mto indicate the off‐ set and size of each block, and a single 1mGNU.sparse.size 22mto in‐ dicate the full size of the file. This is not the same as the size in the tar header because the latter value does not in‐ clude the size of any holes. This format required that the or‐ der of attributes be preserved and relied on readers accepting multiple appearances of the same attribute names, which is not officially permitted by the standards. 1mGNU.sparse.map0m The “0.1” format used a single attribute that stored a comma- separated list of decimal numbers. Each pair of numbers indi‐ cated the offset and size, respectively, of a block of data. This does not work well if the archive is extracted by an archiver that does not recognize this extension, since many pax implementations simply discard unrecognized attributes. 1mGNU.sparse.major22m, 1mGNU.sparse.minor22m, 1mGNU.sparse.name22m, 1mGNU.sparse.realsize0m The “1.0” format stores the sparse block map in one or more 512-byte blocks prepended to the file data in the entry body. The pax attributes indicate the existence of this map (via the 1mGNU.sparse.major 22mand 1mGNU.sparse.minor 22mfields) and the full size of the file. The 1mGNU.sparse.name 22mholds the true name of the file. To avoid confusion, the name stored in the regular tar header is a modified name so that extraction errors will be ap‐ parent to users. 1mSolaris Tar0m XXX More Details Needed XXX Solaris tar (beginning with SunOS XXX 5.7 ?? XXX) supports an “extended” format that is fundamentally similar to pax interchange for‐ mat, with the following differences: 1m• 22mExtended attributes are stored in an entry whose type is 1mX22m, not 1mx22m, as used by pax interchange format. The detailed format of this entry appears to be the same as detailed above for the 1mx0m entry. 1m• 22mAn additional 1mA 22mheader is used to store an ACL for the follow‐ ing regular entry. The body of this entry contains a seven- digit octal number followed by a zero byte, followed by the textual ACL description. The octal value is the number of ACL entries plus a constant that indicates the ACL type: 01000000 for POSIX.1e ACLs and 03000000 for NFSv4 ACLs. 1mAIX Tar0m XXX More details needed XXX AIX Tar uses a ustar-formatted header with the type 1mA 22mfor storing coded ACL information. Unlike the Solaris format, AIX tar writes this header after the regular file body to which it applies. The pathname in this header is either 1mNFS4 22mor 1mAIXC 22mto indicate the type of ACL stored. The actual ACL is stored in platform-specific binary format. 1mMac OS X Tar0m The tar distributed with Apple's Mac OS X stores most regular files as two separate files in the tar archive. The two files have the same name except that the first one has “._” prepended to the last path ele‐ ment. This special file stores an AppleDouble-encoded binary blob with additional metadata about the second file, including ACL, extended at‐ tributes, and resources. To recreate the original file on disk, each separate file can be extracted and the Mac OS X 1mcopyfile22m() function can be used to unpack the separate metadata file and apply it to th regular file. Conversely, the same function provides a “pack” option to encode the extended metadata from a file into a separate file whose contents can then be put into a tar archive. Note that the Apple extended attributes interact badly with long file‐ names. Since each file is stored with the full name, a separate set of extensions needs to be included in the archive for each one, doubling the overhead required for files with long names. 1mSummary of tar type codes0m The following list is a condensed summary of the type codes used in tar header records generated by different tar implementations. More de‐ tails about specific implementations can be found above: NUL Early tar programs stored a zero byte for regular files. 1m0 22mPOSIX standard type code for a regular file. 1m1 22mPOSIX standard type code for a hard link description. 1m2 22mPOSIX standard type code for a symbolic link description. 1m3 22mPOSIX standard type code for a character device node. 1m4 22mPOSIX standard type code for a block device node. 1m5 22mPOSIX standard type code for a directory. 1m6 22mPOSIX standard type code for a FIFO. 1m7 22mPOSIX reserved. 1m7 22mGNU tar used for pre-allocated files on some systems. 1mA 22mSolaris tar ACL description stored prior to a regular file header. 1mA 22mAIX tar ACL description stored after the file body. 1mD 22mGNU tar directory dump. 1mK 22mGNU tar long linkname for the following header. 1mL 22mGNU tar long pathname for the following header. 1mM 22mGNU tar multivolume marker, indicating the file is a continuation of a file from the previous volume. 1mN 22mGNU tar long filename support. Deprecated. 1mS 22mGNU tar sparse regular file. 1mV 22mGNU tar tape/volume header name. 1mX 22mSolaris tar general-purpose extension header. 1mg 22mPOSIX pax interchange format global extensions. 1mx 22mPOSIX pax interchange format per-file extensions. 1mSEE ALSO0m 4mar24m(1), 4mpax24m(1), 4mtar24m(1) 1mSTANDARDS0m The 1mtar 22mutility is no longer a part of POSIX or the Single Unix Stan‐ dard. It last appeared in Version 2 of the Single UNIX Specification (“SUSv2”). It has been supplanted in subsequent standards by 4mpax24m(1). The ustar format is currently part of the specification for the 4mpax24m(1) utility. The pax interchange file format is new with IEEE Std 1003.1-2001 (“POSIX.1”). 1mHISTORY0m A 1mtar 22mcommand appeared in Seventh Edition Unix, which was released in January, 1979. It replaced the 1mtp 22mprogram from Fourth Edition Unix which in turn replaced the 1mtap 22mprogram from First Edition Unix. John Gilmore's 1mpdtar 22mpublic-domain implementation (circa 1987) was highly influential and formed the basis of 1mGNU tar 22m(circa 1988). Joerg Shilling's 1mstar 22marchiver is another open-source (CDDL) archiver (origi‐ nally developed circa 1985) which features complete support for pax in‐ terchange format. d671 2 a672 2 This documentation was written as part of the 1mlibarchive 22mand 1mbsdtar0m project by Tim Kientzle . d674 1 a674 1 Debian December 27, 2016 4mTAR24m(5) @