posix/tar.h

   1 /* Extended tar format from POSIX.1.
   2    Copyright (C) 1992-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _TAR_H
  20 #define _TAR_H  1
  21
  22 #include <features.h>
  23
  24
  25 /* A tar archive consists of 512-byte blocks.
  26    Each file in the archive has a header block followed by 0+ data blocks.
  27    Two blocks of NUL bytes indicate the end of the archive.  */
  28
  29 /* The fields of header blocks:
  30    All strings are stored as ISO 646 (approximately ASCII) strings.
  31
  32    Fields are numeric unless otherwise noted below; numbers are ISO 646
  33    representations of octal numbers, with leading zeros as needed.
  34
  35    linkname is only valid when typeflag==LNKTYPE.  It doesn't use prefix;
  36    files that are links to pathnames >100 chars long can not be stored
  37    in a tar archive.
  38
  39    If typeflag=={LNKTYPE,SYMTYPE,DIRTYPE} then size must be 0.
  40
  41    devmajor and devminor are only valid for typeflag=={BLKTYPE,CHRTYPE}.
  42
  43    chksum contains the sum of all 512 bytes in the header block,
  44    treating each byte as an 8-bit unsigned value and treating the
  45    8 bytes of chksum as blank characters.
  46
  47    uname and gname are used in preference to uid and gid, if those
  48    names exist locally.
  49
  50    Field Name   Byte Offset     Length in Bytes Field Type
  51    name         0               100             NUL-terminated if NUL fits
  52    mode         100             8
  53    uid          108             8
  54    gid          116             8
  55    size         124             12
  56    mtime        136             12
  57    chksum       148             8
  58    typeflag     156             1               see below
  59    linkname     157             100             NUL-terminated if NUL fits
  60    magic        257             6               must be TMAGIC (NUL term.)
  61    version      263             2               must be TVERSION
  62    uname        265             32              NUL-terminated
  63    gname        297             32              NUL-terminated
  64    devmajor     329             8
  65    devminor     337             8
  66    prefix       345             155             NUL-terminated if NUL fits
  67
  68    If the first character of prefix is '\0', the file name is name;
  69    otherwise, it is prefix/name.  Files whose pathnames don't fit in that
  70    length can not be stored in a tar archive.  */
  71
  72 /* The bits in mode: */
  73 #define TSUID   04000
  74 #define TSGID   02000
  75 #if defined __USE_XOPEN || !defined __USE_XOPEN2K
  76 # define TSVTX  01000
  77 #endif
  78 #define TUREAD  00400
  79 #define TUWRITE 00200
  80 #define TUEXEC  00100
  81 #define TGREAD  00040
  82 #define TGWRITE 00020
  83 #define TGEXEC  00010
  84 #define TOREAD  00004
  85 #define TOWRITE 00002
  86 #define TOEXEC  00001
  87
  88 /* The values for typeflag:
  89    Values 'A'-'Z' are reserved for custom implementations.
  90    All other values are reserved for future POSIX.1 revisions.  */
  91
  92 #define REGTYPE         '0'     /* Regular file (preferred code).  */
  93 #define AREGTYPE        '\0'    /* Regular file (alternate code).  */
  94 #define LNKTYPE         '1'     /* Hard link.  */
  95 #define SYMTYPE         '2'     /* Symbolic link (hard if not supported).  */
  96 #define CHRTYPE         '3'     /* Character special.  */
  97 #define BLKTYPE         '4'     /* Block special.  */
  98 #define DIRTYPE         '5'     /* Directory.  */
  99 #define FIFOTYPE        '6'     /* Named pipe.  */
 100 #define CONTTYPE        '7'     /* Contiguous file */
 101  /* (regular file if not supported).  */
 102
 103 /* Contents of magic field and its length.  */
 104 #define TMAGIC  "ustar"
 105 #define TMAGLEN 6
 106
 107 /* Contents of the version field and its length.  */
 108 #define TVERSION        "00"
 109 #define TVERSLEN        2
 110
 111 #endif /* tar.h */