Dogcows Code - chaz/tar/blob - src/tar.h

   1 /* GNU tar Archive Format description.
   2
   3    Copyright (C) 1988, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
   4    2000, 2001, 2003 Free Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 2, or (at your option) any later
   9    version.
  10
  11    This program is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
  14    Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with this program; if not, write to the Free Software Foundation, Inc.,
  18    59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* tar Header Block, from POSIX 1003.1-1990.  */
  21
  22 /* POSIX header.  */
  23
  24 struct posix_header
  25 {                               /* byte offset */
  26   char name[100];               /*   0 */
  27   char mode[8];                 /* 100 */
  28   char uid[8];                  /* 108 */
  29   char gid[8];                  /* 116 */
  30   char size[12];                /* 124 */
  31   char mtime[12];               /* 136 */
  32   char chksum[8];               /* 148 */
  33   char typeflag;                /* 156 */
  34   char linkname[100];           /* 157 */
  35   char magic[6];                /* 257 */
  36   char version[2];              /* 263 */
  37   char uname[32];               /* 265 */
  38   char gname[32];               /* 297 */
  39   char devmajor[8];             /* 329 */
  40   char devminor[8];             /* 337 */
  41   char prefix[155];             /* 345 */
  42                                 /* 500 */
  43 };
  44
  45 struct star_header
  46 {                               /* byte offset */
  47   char name[100];               /*   0 */
  48   char mode[8];                 /* 100 */
  49   char uid[8];                  /* 108 */
  50   char gid[8];                  /* 116 */
  51   char size[12];                /* 124 */
  52   char mtime[12];               /* 136 */
  53   char chksum[8];               /* 148 */
  54   char typeflag;                /* 156 */
  55   char linkname[100];           /* 157 */
  56   char magic[6];                /* 257 */
  57   char version[2];              /* 263 */
  58   char uname[32];               /* 265 */
  59   char gname[32];               /* 297 */
  60   char devmajor[8];             /* 329 */
  61   char devminor[8];             /* 337 */
  62   char prefix[131];             /* 345 */
  63   char atime[12];               /* 476 */
  64   char ctime[12];               /* 488 */
  65                                 /* 500 */
  66 };
  67
  68 #define TMAGIC   "ustar"        /* ustar and a null */
  69 #define TMAGLEN  6
  70 #define TVERSION "00"           /* 00 and no null */
  71 #define TVERSLEN 2
  72
  73 /* Values used in typeflag field.  */
  74 #define REGTYPE  '0'            /* regular file */
  75 #define AREGTYPE '\0'           /* regular file */
  76 #define LNKTYPE  '1'            /* link */
  77 #define SYMTYPE  '2'            /* reserved */
  78 #define CHRTYPE  '3'            /* character special */
  79 #define BLKTYPE  '4'            /* block special */
  80 #define DIRTYPE  '5'            /* directory */
  81 #define FIFOTYPE '6'            /* FIFO special */
  82 #define CONTTYPE '7'            /* reserved */
  83
  84 #define XHDTYPE  'x'            /* Extended header referring to the
  85                                    next file in the archive */
  86 #define XGLTYPE  'g'            /* Global extended header */
  87
  88 /* Bits used in the mode field, values in octal.  */
  89 #define TSUID    04000          /* set UID on execution */
  90 #define TSGID    02000          /* set GID on execution */
  91 #define TSVTX    01000          /* reserved */
  92                                 /* file permissions */
  93 #define TUREAD   00400          /* read by owner */
  94 #define TUWRITE  00200          /* write by owner */
  95 #define TUEXEC   00100          /* execute/search by owner */
  96 #define TGREAD   00040          /* read by group */
  97 #define TGWRITE  00020          /* write by group */
  98 #define TGEXEC   00010          /* execute/search by group */
  99 #define TOREAD   00004          /* read by other */
 100 #define TOWRITE  00002          /* write by other */
 101 #define TOEXEC   00001          /* execute/search by other */
 102
 103 /* tar Header Block, GNU extensions.  */
 104
 105 /* In GNU tar, SYMTYPE is for to symbolic links, and CONTTYPE is for
 106    contiguous files, so maybe disobeying the `reserved' comment in POSIX
 107    header description.  I suspect these were meant to be used this way, and
 108    should not have really been `reserved' in the published standards.  */
 109
 110 /* *BEWARE* *BEWARE* *BEWARE* that the following information is still
 111    boiling, and may change.  Even if the OLDGNU format description should be
 112    accurate, the so-called GNU format is not yet fully decided.  It is
 113    surely meant to use only extensions allowed by POSIX, but the sketch
 114    below repeats some ugliness from the OLDGNU format, which should rather
 115    go away.  Sparse files should be saved in such a way that they do *not*
 116    require two passes at archive creation time.  Huge files get some POSIX
 117    fields to overflow, alternate solutions have to be sought for this.  */
 118
 119 /* Descriptor for a single file hole.  */
 120
 121 struct sparse
 122 {                               /* byte offset */
 123   char offset[12];              /*   0 */
 124   char numbytes[12];            /*  12 */
 125                                 /*  24 */
 126 };
 127
 128 /* Sparse files are not supported in POSIX ustar format.  For sparse files
 129    with a POSIX header, a GNU extra header is provided which holds overall
 130    sparse information and a few sparse descriptors.  When an old GNU header
 131    replaces both the POSIX header and the GNU extra header, it holds some
 132    sparse descriptors too.  Whether POSIX or not, if more sparse descriptors
 133    are still needed, they are put into as many successive sparse headers as
 134    necessary.  The following constants tell how many sparse descriptors fit
 135    in each kind of header able to hold them.  */
 136
 137 #define SPARSES_IN_EXTRA_HEADER  16
 138 #define SPARSES_IN_OLDGNU_HEADER 4
 139 #define SPARSES_IN_SPARSE_HEADER 21
 140
 141 /* Extension header for sparse files, used immediately after the GNU extra
 142    header, and used only if all sparse information cannot fit into that
 143    extra header.  There might even be many such extension headers, one after
 144    the other, until all sparse information has been recorded.  */
 145
 146 struct sparse_header
 147 {                               /* byte offset */
 148   struct sparse sp[SPARSES_IN_SPARSE_HEADER];
 149                                 /*   0 */
 150   char isextended;              /* 504 */
 151                                 /* 505 */
 152 };
 153
 154 /* The old GNU format header conflicts with POSIX format in such a way that
 155    POSIX archives may fool old GNU tar's, and POSIX tar's might well be
 156    fooled by old GNU tar archives.  An old GNU format header uses the space
 157    used by the prefix field in a POSIX header, and cumulates information
 158    normally found in a GNU extra header.  With an old GNU tar header, we
 159    never see any POSIX header nor GNU extra header.  Supplementary sparse
 160    headers are allowed, however.  */
 161
 162 struct oldgnu_header
 163 {                               /* byte offset */
 164   char unused_pad1[345];        /*   0 */
 165   char atime[12];               /* 345 */
 166   char ctime[12];               /* 357 */
 167   char offset[12];              /* 369 */
 168   char longnames[4];            /* 381 */
 169   char unused_pad2;             /* 385 */
 170   struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
 171                                 /* 386 */
 172   char isextended;              /* 482 */
 173   char realsize[12];            /* 483 */
 174                                 /* 495 */
 175 };
 176
 177 /* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
 178    Found in an archive, it indicates an old GNU header format, which will be
 179    hopefully become obsolescent.  With OLDGNU_MAGIC, uname and gname are
 180    valid, though the header is not truly POSIX conforming.  */
 181 #define OLDGNU_MAGIC "ustar  "  /* 7 chars and a null */
 182
 183 /* The standards committee allows only capital A through capital Z for
 184    user-defined expansion.  Other letters in use include:
 185
 186    'A' Solaris Access Control List
 187    'E' Solaris Extended Attribute File
 188    'I' Inode only, as in 'star'
 189    'X' POSIX 1003.1-2001 eXtended (VU version)  */
 190
 191 /* This is a dir entry that contains the names of files that were in the
 192    dir at the time the dump was made.  */
 193 #define GNUTYPE_DUMPDIR 'D'
 194
 195 /* Identifies the *next* file on the tape as having a long linkname.  */
 196 #define GNUTYPE_LONGLINK 'K'
 197
 198 /* Identifies the *next* file on the tape as having a long name.  */
 199 #define GNUTYPE_LONGNAME 'L'
 200
 201 /* This is the continuation of a file that began on another volume.  */
 202 #define GNUTYPE_MULTIVOL 'M'
 203
 204 /* For storing filenames that do not fit into the main header.  */
 205 #define GNUTYPE_NAMES 'N'
 206
 207 /* This is for sparse files.  */
 208 #define GNUTYPE_SPARSE 'S'
 209
 210 /* This file is a tape/volume header.  Ignore it on extraction.  */
 211 #define GNUTYPE_VOLHDR 'V'
 212
 213 /* tar Header Block, overall structure.  */
 214
 215 /* tar files are made in basic blocks of this size.  */
 216 #define BLOCKSIZE 512
 217
 218 enum archive_format
 219 {
 220   DEFAULT_FORMAT,               /* format to be decided later */
 221   V7_FORMAT,                    /* old V7 tar format */
 222   OLDGNU_FORMAT,                /* GNU format as per before tar 1.12 */
 223   USTAR_FORMAT,                 /* POSIX.1-1988 (ustar) format */
 224   POSIX_FORMAT,                 /* POSIX.1-2001 format */
 225   STAR_FORMAT,                  /* Star format defined in 1994 */
 226   GNU_FORMAT                    /* POSIX format with GNU extensions */
 227 };
 228
 229 struct tar_stat_info
 230 {
 231   char *orig_file_name;     /* name of file read from the archive header */
 232   char *file_name;          /* name of file for the current archive entry
 233                                after being normalized.  */
 234   int had_trailing_slash;   /* nonzero if the current archive entry had a
 235                                trailing slash before it was normalized. */
 236   char *link_name;          /* name of link for the current archive entry.  */
 237
 238   unsigned int  devminor;   /* device minor number */
 239   unsigned int  devmajor;   /* device major number */
 240   char          *uname;     /* user name of owner */
 241   char          *gname;     /* group name of owner */
 242   struct stat   stat;       /* regular filesystem stat */
 243 };
 244
 245 union block
 246 {
 247   char buffer[BLOCKSIZE];
 248   struct posix_header header;
 249   struct star_header star_header;
 250   struct oldgnu_header oldgnu_header;
 251   struct sparse_header sparse_header;
 252 };
 253
 254 /* End of Format description.  */