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 #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 \f
 193 /* Jörg Schilling star header */
 194
 195 struct star_header
 196 {                               /* byte offset */
 197   char name[100];               /*   0 */
 198   char mode[8];                 /* 100 */
 199   char uid[8];                  /* 108 */
 200   char gid[8];                  /* 116 */
 201   char size[12];                /* 124 */
 202   char mtime[12];               /* 136 */
 203   char chksum[8];               /* 148 */
 204   char typeflag;                /* 156 */
 205   char linkname[100];           /* 157 */
 206   char magic[6];                /* 257 */
 207   char version[2];              /* 263 */
 208   char uname[32];               /* 265 */
 209   char gname[32];               /* 297 */
 210   char devmajor[8];             /* 329 */
 211   char devminor[8];             /* 337 */
 212   char prefix[131];             /* 345 */
 213   char atime[12];               /* 476 */
 214   char ctime[12];               /* 488 */
 215                                 /* 500 */
 216 };
 217
 218 #define SPARSES_IN_STAR_HEADER      4
 219 #define SPARSES_IN_STAR_EXT_HEADER  21
 220
 221 struct star_in_header {
 222   char fill[345];       /*   0  Everything that is before t_prefix */
 223   char prefix[1];       /* 345  t_name prefix */
 224   char fill2;           /* 346  */
 225   char fill3[8];        /* 347  */
 226   char isextended;      /* 355  */
 227   struct sparse sp[SPARSES_IN_STAR_HEADER]; /* 356  */
 228   char realsize[12];    /* 452  Actual size of the file */
 229   char offset[12];      /* 464  Offset of multivolume contents */
 230   char atime[12];       /* 476  */
 231   char ctime[12];       /* 488  */
 232   char mfill[8];        /* 500  */
 233   char xmagic[4];       /* 508  "tar" */
 234 };
 235
 236 struct star_ext_header {
 237   struct sparse sp[SPARSES_IN_STAR_EXT_HEADER];
 238   char isextended;
 239 };
 240
 241 \f
 242
 243 /* tar Header Block, overall structure.  */
 244
 245 /* tar files are made in basic blocks of this size.  */
 246 #define BLOCKSIZE 512
 247
 248 enum archive_format
 249 {
 250   DEFAULT_FORMAT,               /* format to be decided later */
 251   V7_FORMAT,                    /* old V7 tar format */
 252   OLDGNU_FORMAT,                /* GNU format as per before tar 1.12 */
 253   USTAR_FORMAT,                 /* POSIX.1-1988 (ustar) format */
 254   POSIX_FORMAT,                 /* POSIX.1-2001 format */
 255   STAR_FORMAT,                  /* Star format defined in 1994 */
 256   GNU_FORMAT                    /* POSIX format with GNU extensions */
 257 };
 258
 259 /* Information about a sparse file.  */
 260 struct sp_array
 261   {
 262     off_t offset;
 263     size_t numbytes;
 264   };
 265
 266 struct tar_stat_info
 267 {
 268   char *orig_file_name;     /* name of file read from the archive header */
 269   char *file_name;          /* name of file for the current archive entry
 270                                after being normalized.  */
 271   int had_trailing_slash;   /* nonzero if the current archive entry had a
 272                                trailing slash before it was normalized. */
 273   char *link_name;          /* name of link for the current archive entry.  */
 274
 275   unsigned int  devminor;   /* device minor number */
 276   unsigned int  devmajor;   /* device major number */
 277   char          *uname;     /* user name of owner */
 278   char          *gname;     /* group name of owner */
 279   struct stat   stat;       /* regular filesystem stat */
 280
 281   off_t archive_file_size;  /* Size of file as stored in the archive.
 282                                Equals stat.st_size for non-sparse files */
 283
 284   size_t sparse_map_avail;  /* Index to the first unused element in
 285                                sparse_map array. Zero if the file is
 286                                not sparse */
 287   size_t sparse_map_size;   /* Size of the sparse map */
 288   struct sp_array *sparse_map;
 289 };
 290
 291 union block
 292 {
 293   char buffer[BLOCKSIZE];
 294   struct posix_header header;
 295   struct star_header star_header;
 296   struct oldgnu_header oldgnu_header;
 297   struct sparse_header sparse_header;
 298   struct star_in_header star_in_header;
 299   struct star_ext_header star_ext_header;
 300 };
 301
 302 /* End of Format description.  */