include/tar.h

   1 /* Extended tar format from POSIX.1.
   2    Copyright (C) 1992-2021 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Written by David J. MacKenzie.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #ifndef _TAR_H
  21 #define _TAR_H  1
  22
  23 #include <features.h>
  24
  25
  26 /* A tar archive consists of 512-byte blocks.
  27    Each file in the archive has a header block followed by 0+ data blocks.
  28    Two blocks of NUL bytes indicate the end of the archive.  */
  29
  30 /* The fields of header blocks:
  31    All strings are stored as ISO 646 (approximately ASCII) strings.
  32
  33    Fields are numeric unless otherwise noted below; numbers are ISO 646
  34    representations of octal numbers, with leading zeros as needed.
  35
  36    linkname is only valid when typeflag==LNKTYPE.  It doesn't use prefix;
  37    files that are links to pathnames >100 chars long can not be stored
  38    in a tar archive.
  39
  40    If typeflag=={LNKTYPE,SYMTYPE,DIRTYPE} then size must be 0.
  41
  42    devmajor and devminor are only valid for typeflag=={BLKTYPE,CHRTYPE}.
  43
  44    chksum contains the sum of all 512 bytes in the header block,
  45    treating each byte as an 8-bit unsigned value and treating the
  46    8 bytes of chksum as blank characters.
  47
  48    uname and gname are used in preference to uid and gid, if those
  49    names exist locally.
  50
  51    Field Name   Byte Offset     Length in Bytes Field Type
  52    name         0               100             NUL-terminated if NUL fits
  53    mode         100             8
  54    uid          108             8
  55    gid          116             8
  56    size         124             12
  57    mtime        136             12
  58    chksum       148             8
  59    typeflag     156             1               see below
  60    linkname     157             100             NUL-terminated if NUL fits
  61    magic        257             6               must be TMAGIC (NUL term.)
  62    version      263             2               must be TVERSION
  63    uname        265             32              NUL-terminated
  64    gname        297             32              NUL-terminated
  65    devmajor     329             8
  66    devminor     337             8
  67    prefix       345             155             NUL-terminated if NUL fits
  68
  69    If the first character of prefix is '\0', the file name is name;
  70    otherwise, it is prefix/name.  Files whose pathnames don't fit in that
  71    length can not be stored in a tar archive.  */
  72
  73 /* The bits in mode: */
  74 #define TSUID   04000
  75 #define TSGID   02000
  76 #if defined __USE_XOPEN || !defined __USE_XOPEN2K
  77 # define TSVTX  01000
  78 #endif
  79 #define TUREAD  00400
  80 #define TUWRITE 00200
  81 #define TUEXEC  00100
  82 #define TGREAD  00040
  83 #define TGWRITE 00020
  84 #define TGEXEC  00010
  85 #define TOREAD  00004
  86 #define TOWRITE 00002
  87 #define TOEXEC  00001
  88
  89 /* The values for typeflag:
  90    Values 'A'-'Z' are reserved for custom implementations.
  91    All other values are reserved for future POSIX.1 revisions.  */
  92
  93 #define REGTYPE         '0'     /* Regular file (preferred code).  */
  94 #define AREGTYPE        '\0'    /* Regular file (alternate code).  */
  95 #define LNKTYPE         '1'     /* Hard link.  */
  96 #define SYMTYPE         '2'     /* Symbolic link (hard if not supported).  */
  97 #define CHRTYPE         '3'     /* Character special.  */
  98 #define BLKTYPE         '4'     /* Block special.  */
  99 #define DIRTYPE         '5'     /* Directory.  */
 100 #define FIFOTYPE        '6'     /* Named pipe.  */
 101 #define CONTTYPE        '7'     /* Contiguous file */
 102  /* (regular file if not supported).  */
 103
 104 /* Contents of magic field and its length.  */
 105 #define TMAGIC  "ustar"
 106 #define TMAGLEN 6
 107
 108 /* Contents of the version field and its length.  */
 109 #define TVERSION        "00"
 110 #define TVERSLEN        2
 111
 112 #endif /* tar.h */