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 /* If OLDGNU_COMPATIBILITY is not zero, tar produces archives which, by
  21    default, are readable by older versions of GNU tar.  This can be
  22    overriden by using --posix; in this case, POSIXLY_CORRECT in environment
  23    may be set for enforcing stricter conformance.  If OLDGNU_COMPATIBILITY
  24    is zero or undefined, tar will eventually produces archives which, by
  25    default, POSIX compatible; then either using --posix or defining
  26    POSIXLY_CORRECT enforces stricter conformance.
  27
  28    This #define will disappear in a few years.  FP, June 1995.  */
  29 #define OLDGNU_COMPATIBILITY 1
  30
  31 /* tar Header Block, from POSIX 1003.1-1990.  */
  32
  33 /* POSIX header.  */
  34
  35 struct posix_header
  36 {                               /* byte offset */
  37   char name[100];               /*   0 */
  38   char mode[8];                 /* 100 */
  39   char uid[8];                  /* 108 */
  40   char gid[8];                  /* 116 */
  41   char size[12];                /* 124 */
  42   char mtime[12];               /* 136 */
  43   char chksum[8];               /* 148 */
  44   char typeflag;                /* 156 */
  45   char linkname[100];           /* 157 */
  46   char magic[6];                /* 257 */
  47   char version[2];              /* 263 */
  48   char uname[32];               /* 265 */
  49   char gname[32];               /* 297 */
  50   char devmajor[8];             /* 329 */
  51   char devminor[8];             /* 337 */
  52   char prefix[155];             /* 345 */
  53                                 /* 500 */
  54 };
  55
  56 struct star_header
  57 {                               /* byte offset */
  58   char name[100];               /*   0 */
  59   char mode[8];                 /* 100 */
  60   char uid[8];                  /* 108 */
  61   char gid[8];                  /* 116 */
  62   char size[12];                /* 124 */
  63   char mtime[12];               /* 136 */
  64   char chksum[8];               /* 148 */
  65   char typeflag;                /* 156 */
  66   char linkname[100];           /* 157 */
  67   char magic[6];                /* 257 */
  68   char version[2];              /* 263 */
  69   char uname[32];               /* 265 */
  70   char gname[32];               /* 297 */
  71   char devmajor[8];             /* 329 */
  72   char devminor[8];             /* 337 */
  73   char prefix[131];             /* 345 */
  74   char atime[12];               /* 476 */
  75   char ctime[12];               /* 488 */
  76                                 /* 500 */
  77 };
  78
  79 #define TMAGIC   "ustar"        /* ustar and a null */
  80 #define TMAGLEN  6
  81 #define TVERSION "00"           /* 00 and no null */
  82 #define TVERSLEN 2
  83
  84 /* Values used in typeflag field.  */
  85 #define REGTYPE  '0'            /* regular file */
  86 #define AREGTYPE '\0'           /* regular file */
  87 #define LNKTYPE  '1'            /* link */
  88 #define SYMTYPE  '2'            /* reserved */
  89 #define CHRTYPE  '3'            /* character special */
  90 #define BLKTYPE  '4'            /* block special */
  91 #define DIRTYPE  '5'            /* directory */
  92 #define FIFOTYPE '6'            /* FIFO special */
  93 #define CONTTYPE '7'            /* reserved */
  94
  95 #define XHDTYPE  'x'            /* Extended header referring to the
  96                                    next file in the archive */
  97 #define XGLTYPE  'g'            /* Global extended header */
  98
  99 /* Bits used in the mode field, values in octal.  */
 100 #define TSUID    04000          /* set UID on execution */
 101 #define TSGID    02000          /* set GID on execution */
 102 #define TSVTX    01000          /* reserved */
 103                                 /* file permissions */
 104 #define TUREAD   00400          /* read by owner */
 105 #define TUWRITE  00200          /* write by owner */
 106 #define TUEXEC   00100          /* execute/search by owner */
 107 #define TGREAD   00040          /* read by group */
 108 #define TGWRITE  00020          /* write by group */
 109 #define TGEXEC   00010          /* execute/search by group */
 110 #define TOREAD   00004          /* read by other */
 111 #define TOWRITE  00002          /* write by other */
 112 #define TOEXEC   00001          /* execute/search by other */
 113
 114 /* tar Header Block, GNU extensions.  */
 115
 116 /* In GNU tar, SYMTYPE is for to symbolic links, and CONTTYPE is for
 117    contiguous files, so maybe disobeying the `reserved' comment in POSIX
 118    header description.  I suspect these were meant to be used this way, and
 119    should not have really been `reserved' in the published standards.  */
 120
 121 /* *BEWARE* *BEWARE* *BEWARE* that the following information is still
 122    boiling, and may change.  Even if the OLDGNU format description should be
 123    accurate, the so-called GNU format is not yet fully decided.  It is
 124    surely meant to use only extensions allowed by POSIX, but the sketch
 125    below repeats some ugliness from the OLDGNU format, which should rather
 126    go away.  Sparse files should be saved in such a way that they do *not*
 127    require two passes at archive creation time.  Huge files get some POSIX
 128    fields to overflow, alternate solutions have to be sought for this.  */
 129
 130 /* Descriptor for a single file hole.  */
 131
 132 struct sparse
 133 {                               /* byte offset */
 134   char offset[12];              /*   0 */
 135   char numbytes[12];            /*  12 */
 136                                 /*  24 */
 137 };
 138
 139 /* Sparse files are not supported in POSIX ustar format.  For sparse files
 140    with a POSIX header, a GNU extra header is provided which holds overall
 141    sparse information and a few sparse descriptors.  When an old GNU header
 142    replaces both the POSIX header and the GNU extra header, it holds some
 143    sparse descriptors too.  Whether POSIX or not, if more sparse descriptors
 144    are still needed, they are put into as many successive sparse headers as
 145    necessary.  The following constants tell how many sparse descriptors fit
 146    in each kind of header able to hold them.  */
 147
 148 #define SPARSES_IN_EXTRA_HEADER  16
 149 #define SPARSES_IN_OLDGNU_HEADER 4
 150 #define SPARSES_IN_SPARSE_HEADER 21
 151
 152 /* The GNU extra header contains some information GNU tar needs, but not
 153    foreseen in POSIX header format.  It is only used after a POSIX header
 154    (and never with old GNU headers), and immediately follows this POSIX
 155    header, when typeflag is a letter rather than a digit, so signaling a GNU
 156    extension.  */
 157
 158 struct extra_header
 159 {                               /* byte offset */
 160   char atime[12];               /*   0 */
 161   char ctime[12];               /*  12 */
 162   char offset[12];              /*  24 */
 163   char realsize[12];            /*  36 */
 164   char longnames[4];            /*  48 */
 165   char unused_pad1[68];         /*  52 */
 166   struct sparse sp[SPARSES_IN_EXTRA_HEADER];
 167                                 /* 120 */
 168   char isextended;              /* 504 */
 169                                 /* 505 */
 170 };
 171
 172 /* Extension header for sparse files, used immediately after the GNU extra
 173    header, and used only if all sparse information cannot fit into that
 174    extra header.  There might even be many such extension headers, one after
 175    the other, until all sparse information has been recorded.  */
 176
 177 struct sparse_header
 178 {                               /* byte offset */
 179   struct sparse sp[SPARSES_IN_SPARSE_HEADER];
 180                                 /*   0 */
 181   char isextended;              /* 504 */
 182                                 /* 505 */
 183 };
 184
 185 /* The old GNU format header conflicts with POSIX format in such a way that
 186    POSIX archives may fool old GNU tar's, and POSIX tar's might well be
 187    fooled by old GNU tar archives.  An old GNU format header uses the space
 188    used by the prefix field in a POSIX header, and cumulates information
 189    normally found in a GNU extra header.  With an old GNU tar header, we
 190    never see any POSIX header nor GNU extra header.  Supplementary sparse
 191    headers are allowed, however.  */
 192
 193 struct oldgnu_header
 194 {                               /* byte offset */
 195   char unused_pad1[345];        /*   0 */
 196   char atime[12];               /* 345 */
 197   char ctime[12];               /* 357 */
 198   char offset[12];              /* 369 */
 199   char longnames[4];            /* 381 */
 200   char unused_pad2;             /* 385 */
 201   struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
 202                                 /* 386 */
 203   char isextended;              /* 482 */
 204   char realsize[12];            /* 483 */
 205                                 /* 495 */
 206 };
 207
 208 /* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
 209    Found in an archive, it indicates an old GNU header format, which will be
 210    hopefully become obsolescent.  With OLDGNU_MAGIC, uname and gname are
 211    valid, though the header is not truly POSIX conforming.  */
 212 #define OLDGNU_MAGIC "ustar  "  /* 7 chars and a null */
 213
 214 /* The standards committee allows only capital A through capital Z for
 215    user-defined expansion.  Other letters in use include:
 216
 217    'A' Solaris Access Control List
 218    'E' Solaris Extended Attribute File
 219    'I' Inode only, as in 'star'
 220    'X' POSIX 1003.1-2001 eXtended (VU version)  */
 221
 222 /* This is a dir entry that contains the names of files that were in the
 223    dir at the time the dump was made.  */
 224 #define GNUTYPE_DUMPDIR 'D'
 225
 226 /* Identifies the *next* file on the tape as having a long linkname.  */
 227 #define GNUTYPE_LONGLINK 'K'
 228
 229 /* Identifies the *next* file on the tape as having a long name.  */
 230 #define GNUTYPE_LONGNAME 'L'
 231
 232 /* This is the continuation of a file that began on another volume.  */
 233 #define GNUTYPE_MULTIVOL 'M'
 234
 235 /* For storing filenames that do not fit into the main header.  */
 236 #define GNUTYPE_NAMES 'N'
 237
 238 /* This is for sparse files.  */
 239 #define GNUTYPE_SPARSE 'S'
 240
 241 /* This file is a tape/volume header.  Ignore it on extraction.  */
 242 #define GNUTYPE_VOLHDR 'V'
 243
 244 /* tar Header Block, overall structure.  */
 245
 246 /* tar files are made in basic blocks of this size.  */
 247 #define BLOCKSIZE 512
 248
 249 enum archive_format
 250 {
 251   DEFAULT_FORMAT,               /* format to be decided later */
 252   V7_FORMAT,                    /* old V7 tar format */
 253   OLDGNU_FORMAT,                /* GNU format as per before tar 1.12 */
 254   POSIX_FORMAT,                 /* restricted, pure POSIX format */
 255   STAR_FORMAT,                  /* Star format defined in 1994 */
 256   GNU_FORMAT                    /* POSIX format with GNU extensions */
 257 };
 258
 259 struct tar_stat_info
 260 {
 261   char *orig_file_name;     /* name of file read from the archive header */
 262   char *file_name;          /* name of file for the current archive entry
 263                                after being normalized.  */
 264   int had_trailing_slash;   /* nonzero if the current archive entry had a
 265                                trailing slash before it was normalized. */
 266   char *link_name;          /* name of link for the current archive entry.  */
 267
 268   unsigned int  devminor;   /* device minor number */
 269   unsigned int  devmajor;   /* device major number */
 270   char          *uname;     /* user name of owner */
 271   char          *gname;     /* group name of owner */
 272   struct stat   stat;       /* regular filesystem stat */
 273 };
 274
 275 union block
 276 {
 277   char buffer[BLOCKSIZE];
 278   struct posix_header header;
 279   struct star_header star_header;
 280   struct extra_header extra_header;
 281   struct oldgnu_header oldgnu_header;
 282   struct sparse_header sparse_header;
 283 };
 284
 285 /* End of Format description.  */