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 Incr. archive: atime of the file */
 166   char ctime[12];               /* 357 Incr. archive: ctime of the file */
 167   char offset[12];              /* 369 Multivolume archive: the offset of
 168                                    the start of this volume */
 169   char longnames[4];            /* 381 Not used */
 170   char unused_pad2;             /* 385 */
 171   struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
 172                                 /* 386 */
 173   char isextended;              /* 482 Sparse file: Extension sparse header
 174                                    follows */
 175   char realsize[12];            /* 483 Sparse file: Real size*/
 176                                 /* 495 */
 177 };
 178
 179 /* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
 180    Found in an archive, it indicates an old GNU header format, which will be
 181    hopefully become obsolescent.  With OLDGNU_MAGIC, uname and gname are
 182    valid, though the header is not truly POSIX conforming.  */
 183 #define OLDGNU_MAGIC "ustar  "  /* 7 chars and a null */
 184
 185 /* The standards committee allows only capital A through capital Z for
 186    user-defined expansion.  Other letters in use include:
 187
 188    'A' Solaris Access Control List
 189    'E' Solaris Extended Attribute File
 190    'I' Inode only, as in 'star'
 191    'X' POSIX 1003.1-2001 eXtended (VU version)  */
 192
 193 /* This is a dir entry that contains the names of files that were in the
 194    dir at the time the dump was made.  */
 195 #define GNUTYPE_DUMPDIR 'D'
 196
 197 /* Identifies the *next* file on the tape as having a long linkname.  */
 198 #define GNUTYPE_LONGLINK 'K'
 199
 200 /* Identifies the *next* file on the tape as having a long name.  */
 201 #define GNUTYPE_LONGNAME 'L'
 202
 203 /* This is the continuation of a file that began on another volume.  */
 204 #define GNUTYPE_MULTIVOL 'M'
 205
 206 /* For storing filenames that do not fit into the main header.  */
 207 #define GNUTYPE_NAMES 'N'
 208
 209 /* This is for sparse files.  */
 210 #define GNUTYPE_SPARSE 'S'
 211
 212 /* This file is a tape/volume header.  Ignore it on extraction.  */
 213 #define GNUTYPE_VOLHDR 'V'
 214
 215 /* tar Header Block, overall structure.  */
 216
 217 /* tar files are made in basic blocks of this size.  */
 218 #define BLOCKSIZE 512
 219
 220 enum archive_format
 221 {
 222   DEFAULT_FORMAT,               /* format to be decided later */
 223   V7_FORMAT,                    /* old V7 tar format */
 224   OLDGNU_FORMAT,                /* GNU format as per before tar 1.12 */
 225   USTAR_FORMAT,                 /* POSIX.1-1988 (ustar) format */
 226   POSIX_FORMAT,                 /* POSIX.1-2001 format */
 227   STAR_FORMAT,                  /* Star format defined in 1994 */
 228   GNU_FORMAT                    /* POSIX format with GNU extensions */
 229 };
 230
 231 /* Information about a sparse file.  */
 232 struct sp_array
 233   {
 234     off_t offset;
 235     size_t numbytes;
 236   };
 237
 238 struct tar_stat_info
 239 {
 240   char *orig_file_name;     /* name of file read from the archive header */
 241   char *file_name;          /* name of file for the current archive entry
 242                                after being normalized.  */
 243   int had_trailing_slash;   /* nonzero if the current archive entry had a
 244                                trailing slash before it was normalized. */
 245   char *link_name;          /* name of link for the current archive entry.  */
 246
 247   unsigned int  devminor;   /* device minor number */
 248   unsigned int  devmajor;   /* device major number */
 249   char          *uname;     /* user name of owner */
 250   char          *gname;     /* group name of owner */
 251   struct stat   stat;       /* regular filesystem stat */
 252
 253   off_t archive_file_size;  /* Size of file as stored in the archive.
 254                                Equals stat.st_size for non-sparse files */
 255
 256   size_t sparse_map_avail;  /* Index to the first unused element in
 257                                sparse_map array. Zero if the file is
 258                                not sparse */
 259   size_t sparse_map_size;   /* Size of the sparse map */
 260   struct sp_array *sparse_map;
 261 };
 262
 263 union block
 264 {
 265   char buffer[BLOCKSIZE];
 266   struct posix_header header;
 267   struct star_header star_header;
 268   struct oldgnu_header oldgnu_header;
 269   struct sparse_header sparse_header;
 270 };
 271
 272 /* End of Format description.  */