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, 2004, 2005 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    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 #define TMAGIC   "ustar"        /* ustar and a null */
  46 #define TMAGLEN  6
  47 #define TVERSION "00"           /* 00 and no null */
  48 #define TVERSLEN 2
  49
  50 /* Values used in typeflag field.  */
  51 #define REGTYPE  '0'            /* regular file */
  52 #define AREGTYPE '\0'           /* regular file */
  53 #define LNKTYPE  '1'            /* link */
  54 #define SYMTYPE  '2'            /* reserved */
  55 #define CHRTYPE  '3'            /* character special */
  56 #define BLKTYPE  '4'            /* block special */
  57 #define DIRTYPE  '5'            /* directory */
  58 #define FIFOTYPE '6'            /* FIFO special */
  59 #define CONTTYPE '7'            /* reserved */
  60
  61 #define XHDTYPE  'x'            /* Extended header referring to the
  62                                    next file in the archive */
  63 #define XGLTYPE  'g'            /* Global extended header */
  64
  65 /* Bits used in the mode field, values in octal.  */
  66 #define TSUID    04000          /* set UID on execution */
  67 #define TSGID    02000          /* set GID on execution */
  68 #define TSVTX    01000          /* reserved */
  69                                 /* file permissions */
  70 #define TUREAD   00400          /* read by owner */
  71 #define TUWRITE  00200          /* write by owner */
  72 #define TUEXEC   00100          /* execute/search by owner */
  73 #define TGREAD   00040          /* read by group */
  74 #define TGWRITE  00020          /* write by group */
  75 #define TGEXEC   00010          /* execute/search by group */
  76 #define TOREAD   00004          /* read by other */
  77 #define TOWRITE  00002          /* write by other */
  78 #define TOEXEC   00001          /* execute/search by other */
  79
  80 /* tar Header Block, GNU extensions.  */
  81
  82 /* In GNU tar, SYMTYPE is for to symbolic links, and CONTTYPE is for
  83    contiguous files, so maybe disobeying the `reserved' comment in POSIX
  84    header description.  I suspect these were meant to be used this way, and
  85    should not have really been `reserved' in the published standards.  */
  86
  87 /* *BEWARE* *BEWARE* *BEWARE* that the following information is still
  88    boiling, and may change.  Even if the OLDGNU format description should be
  89    accurate, the so-called GNU format is not yet fully decided.  It is
  90    surely meant to use only extensions allowed by POSIX, but the sketch
  91    below repeats some ugliness from the OLDGNU format, which should rather
  92    go away.  Sparse files should be saved in such a way that they do *not*
  93    require two passes at archive creation time.  Huge files get some POSIX
  94    fields to overflow, alternate solutions have to be sought for this.  */
  95
  96 /* Descriptor for a single file hole.  */
  97
  98 struct sparse
  99 {                               /* byte offset */
 100   char offset[12];              /*   0 */
 101   char numbytes[12];            /*  12 */
 102                                 /*  24 */
 103 };
 104
 105 /* Sparse files are not supported in POSIX ustar format.  For sparse files
 106    with a POSIX header, a GNU extra header is provided which holds overall
 107    sparse information and a few sparse descriptors.  When an old GNU header
 108    replaces both the POSIX header and the GNU extra header, it holds some
 109    sparse descriptors too.  Whether POSIX or not, if more sparse descriptors
 110    are still needed, they are put into as many successive sparse headers as
 111    necessary.  The following constants tell how many sparse descriptors fit
 112    in each kind of header able to hold them.  */
 113
 114 #define SPARSES_IN_EXTRA_HEADER  16
 115 #define SPARSES_IN_OLDGNU_HEADER 4
 116 #define SPARSES_IN_SPARSE_HEADER 21
 117
 118 /* Extension header for sparse files, used immediately after the GNU extra
 119    header, and used only if all sparse information cannot fit into that
 120    extra header.  There might even be many such extension headers, one after
 121    the other, until all sparse information has been recorded.  */
 122
 123 struct sparse_header
 124 {                               /* byte offset */
 125   struct sparse sp[SPARSES_IN_SPARSE_HEADER];
 126                                 /*   0 */
 127   char isextended;              /* 504 */
 128                                 /* 505 */
 129 };
 130
 131 /* The old GNU format header conflicts with POSIX format in such a way that
 132    POSIX archives may fool old GNU tar's, and POSIX tar's might well be
 133    fooled by old GNU tar archives.  An old GNU format header uses the space
 134    used by the prefix field in a POSIX header, and cumulates information
 135    normally found in a GNU extra header.  With an old GNU tar header, we
 136    never see any POSIX header nor GNU extra header.  Supplementary sparse
 137    headers are allowed, however.  */
 138
 139 struct oldgnu_header
 140 {                               /* byte offset */
 141   char unused_pad1[345];        /*   0 */
 142   char atime[12];               /* 345 Incr. archive: atime of the file */
 143   char ctime[12];               /* 357 Incr. archive: ctime of the file */
 144   char offset[12];              /* 369 Multivolume archive: the offset of
 145                                    the start of this volume */
 146   char longnames[4];            /* 381 Not used */
 147   char unused_pad2;             /* 385 */
 148   struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
 149                                 /* 386 */
 150   char isextended;              /* 482 Sparse file: Extension sparse header
 151                                    follows */
 152   char realsize[12];            /* 483 Sparse file: Real size*/
 153                                 /* 495 */
 154 };
 155
 156 /* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
 157    Found in an archive, it indicates an old GNU header format, which will be
 158    hopefully become obsolescent.  With OLDGNU_MAGIC, uname and gname are
 159    valid, though the header is not truly POSIX conforming.  */
 160 #define OLDGNU_MAGIC "ustar  "  /* 7 chars and a null */
 161
 162 /* The standards committee allows only capital A through capital Z for
 163    user-defined expansion.  Other letters in use include:
 164
 165    'A' Solaris Access Control List
 166    'E' Solaris Extended Attribute File
 167    'I' Inode only, as in 'star'
 168    'X' POSIX 1003.1-2001 eXtended (VU version)  */
 169
 170 /* This is a dir entry that contains the names of files that were in the
 171    dir at the time the dump was made.  */
 172 #define GNUTYPE_DUMPDIR 'D'
 173
 174 /* Identifies the *next* file on the tape as having a long linkname.  */
 175 #define GNUTYPE_LONGLINK 'K'
 176
 177 /* Identifies the *next* file on the tape as having a long name.  */
 178 #define GNUTYPE_LONGNAME 'L'
 179
 180 /* This is the continuation of a file that began on another volume.  */
 181 #define GNUTYPE_MULTIVOL 'M'
 182
 183 /* For storing filenames that do not fit into the main header.  */
 184 #define GNUTYPE_NAMES 'N'
 185
 186 /* This is for sparse files.  */
 187 #define GNUTYPE_SPARSE 'S'
 188
 189 /* This file is a tape/volume header.  Ignore it on extraction.  */
 190 #define GNUTYPE_VOLHDR 'V'
 191
 192 /* Solaris extended header */
 193 #define SOLARIS_XHDTYPE 'X'
 194
 195 \f
 196 /* Jörg Schilling star header */
 197
 198 struct star_header
 199 {                               /* byte offset */
 200   char name[100];               /*   0 */
 201   char mode[8];                 /* 100 */
 202   char uid[8];                  /* 108 */
 203   char gid[8];                  /* 116 */
 204   char size[12];                /* 124 */
 205   char mtime[12];               /* 136 */
 206   char chksum[8];               /* 148 */
 207   char typeflag;                /* 156 */
 208   char linkname[100];           /* 157 */
 209   char magic[6];                /* 257 */
 210   char version[2];              /* 263 */
 211   char uname[32];               /* 265 */
 212   char gname[32];               /* 297 */
 213   char devmajor[8];             /* 329 */
 214   char devminor[8];             /* 337 */
 215   char prefix[131];             /* 345 */
 216   char atime[12];               /* 476 */
 217   char ctime[12];               /* 488 */
 218                                 /* 500 */
 219 };
 220
 221 #define SPARSES_IN_STAR_HEADER      4
 222 #define SPARSES_IN_STAR_EXT_HEADER  21
 223
 224 struct star_in_header {
 225   char fill[345];       /*   0  Everything that is before t_prefix */
 226   char prefix[1];       /* 345  t_name prefix */
 227   char fill2;           /* 346  */
 228   char fill3[8];        /* 347  */
 229   char isextended;      /* 355  */
 230   struct sparse sp[SPARSES_IN_STAR_HEADER]; /* 356  */
 231   char realsize[12];    /* 452  Actual size of the file */
 232   char offset[12];      /* 464  Offset of multivolume contents */
 233   char atime[12];       /* 476  */
 234   char ctime[12];       /* 488  */
 235   char mfill[8];        /* 500  */
 236   char xmagic[4];       /* 508  "tar" */
 237 };
 238
 239 struct star_ext_header {
 240   struct sparse sp[SPARSES_IN_STAR_EXT_HEADER];
 241   char isextended;
 242 };
 243
 244 \f
 245
 246 /* tar Header Block, overall structure.  */
 247
 248 /* tar files are made in basic blocks of this size.  */
 249 #define BLOCKSIZE 512
 250
 251 enum archive_format
 252 {
 253   DEFAULT_FORMAT,               /* format to be decided later */
 254   V7_FORMAT,                    /* old V7 tar format */
 255   OLDGNU_FORMAT,                /* GNU format as per before tar 1.12 */
 256   USTAR_FORMAT,                 /* POSIX.1-1988 (ustar) format */
 257   POSIX_FORMAT,                 /* POSIX.1-2001 format */
 258   STAR_FORMAT,                  /* Star format defined in 1994 */
 259   GNU_FORMAT                    /* Same as OLDGNU_FORMAT with one exception:
 260                                    see FIXME note for to_chars() function
 261                                    (create.c:189) */
 262 };
 263
 264 /* Information about a sparse file.  */
 265 struct sp_array
 266   {
 267     off_t offset;
 268     size_t numbytes;
 269   };
 270
 271 struct tar_stat_info
 272 {
 273   char *orig_file_name;     /* name of file read from the archive header */
 274   char *file_name;          /* name of file for the current archive entry
 275                                after being normalized.  */
 276   bool had_trailing_slash;  /* true if the current archive entry had a
 277                                trailing slash before it was normalized. */
 278   char *link_name;          /* name of link for the current archive entry.  */
 279
 280   char          *uname;     /* user name of owner */
 281   char          *gname;     /* group name of owner */
 282   struct stat   stat;       /* regular filesystem stat */
 283
 284   /* STAT doesn't always have access, data modification, and status
 285      change times in a convenient form, so store them separately.  */
 286   struct timespec atime;
 287   struct timespec mtime;
 288   struct timespec ctime;
 289
 290   off_t archive_file_size;  /* Size of file as stored in the archive.
 291                                Equals stat.st_size for non-sparse files */
 292
 293   bool   is_sparse;         /* Is the file sparse */
 294
 295   /* For sparse files: */
 296   size_t sparse_map_avail;  /* Index to the first unused element in
 297                                sparse_map array. Zero if the file is
 298                                not sparse */
 299   size_t sparse_map_size;   /* Size of the sparse map */
 300   struct sp_array *sparse_map;
 301
 302   /* For dumpdirs */
 303   char *dumpdir;
 304 };
 305
 306 union block
 307 {
 308   char buffer[BLOCKSIZE];
 309   struct posix_header header;
 310   struct star_header star_header;
 311   struct oldgnu_header oldgnu_header;
 312   struct sparse_header sparse_header;
 313   struct star_in_header star_in_header;
 314   struct star_ext_header star_ext_header;
 315 };
 316
 317 /* End of Format description.  */