Dogcows Code - chaz/tar/blob - src/delete.c

   1 /* Delete entries from a tar archive.
   2
   3    Copyright (C) 1988, 1992, 1994, 1996, 1997, 2000, 2001, 2003 Free
   4    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 #include "system.h"
  21
  22 #include "common.h"
  23 #include "rmt.h"
  24
  25 static union block *new_record;
  26 static int new_blocks;
  27 static bool acting_as_filter;
  28
  29 /* FIXME: This module should not directly handle the following
  30    variables, instead, the interface should be cleaned up.  */
  31 extern union block *record_start;
  32 extern union block *record_end;
  33 extern union block *current_block;
  34 extern union block *recent_long_name;
  35 extern union block *recent_long_link;
  36 extern off_t records_read;
  37 extern off_t records_written;
  38
  39 /* The number of records skipped at the start of the archive, when
  40    passing over members that are not deleted.  */
  41 static off_t records_skipped;
  42
  43 /* Move archive descriptor by COUNT records worth.  If COUNT is
  44    positive we move forward, else we move negative.  If it's a tape,
  45    MTIOCTOP had better work.  If it's something else, we try to seek
  46    on it.  If we can't seek, we lose!  */
  47 static void
  48 move_archive (off_t count)
  49 {
  50   if (count == 0)
  51     return;
  52
  53 #ifdef MTIOCTOP
  54   {
  55     struct mtop operation;
  56
  57     if (count < 0
  58         ? (operation.mt_op = MTBSR,
  59            operation.mt_count = -count,
  60            operation.mt_count == -count)
  61         : (operation.mt_op = MTFSR,
  62            operation.mt_count = count,
  63            operation.mt_count == count))
  64       {
  65         if (0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  66           return;
  67
  68         if (errno == EIO
  69             && 0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  70           return;
  71       }
  72   }
  73 #endif /* MTIOCTOP */
  74
  75   {
  76     off_t position0 = rmtlseek (archive, (off_t) 0, SEEK_CUR);
  77     off_t increment = record_size * (off_t) count;
  78     off_t position = position0 + increment;
  79
  80     if (increment / count != record_size
  81         || (position < position0) != (increment < 0)
  82         || (position = position < 0 ? 0 : position,
  83             rmtlseek (archive, position, SEEK_SET) != position))
  84       seek_error_details (archive_name_array[0], position);
  85
  86     return;
  87   }
  88 }
  89
  90 /* Write out the record which has been filled.  If MOVE_BACK_FLAG,
  91    backspace to where we started.  */
  92 static void
  93 write_record (int move_back_flag)
  94 {
  95   union block *save_record = record_start;
  96   record_start = new_record;
  97
  98   if (acting_as_filter)
  99     {
 100       archive = STDOUT_FILENO;
 101       flush_write ();
 102       archive = STDIN_FILENO;
 103     }
 104   else
 105     {
 106       move_archive ((records_written + records_skipped) - records_read);
 107       flush_write ();
 108     }
 109
 110   record_start = save_record;
 111
 112   if (move_back_flag)
 113     {
 114       /* Move the tape head back to where we were.  */
 115
 116       if (! acting_as_filter)
 117         move_archive (records_read - (records_written + records_skipped));
 118     }
 119
 120   new_blocks = 0;
 121 }
 122
 123 static void
 124 write_recent_blocks (union block *h, size_t blocks)
 125 {
 126   size_t i;
 127   for (i = 0; i < blocks; i++)
 128     {
 129       new_record[new_blocks++] = h[i];
 130       if (new_blocks == blocking_factor)
 131         write_record (1);
 132     }
 133 }
 134
 135 void
 136 delete_archive_members (void)
 137 {
 138   enum read_header logical_status = HEADER_STILL_UNREAD;
 139   enum read_header previous_status = HEADER_STILL_UNREAD;
 140
 141   /* FIXME: Should clean the routine before cleaning these variables :-( */
 142   struct name *name;
 143   off_t blocks_to_skip = 0;
 144   off_t blocks_to_keep = 0;
 145   int kept_blocks_in_record;
 146
 147   name_gather ();
 148   open_archive (ACCESS_UPDATE);
 149   acting_as_filter = strcmp (archive_name_array[0], "-") == 0;
 150
 151   do
 152     {
 153       enum read_header status = read_header (1);
 154
 155       switch (status)
 156         {
 157         case HEADER_STILL_UNREAD:
 158           abort ();
 159
 160         case HEADER_SUCCESS:
 161           if (name = name_scan (current_stat_info.file_name), !name)
 162             {
 163               skip_member ();
 164               break;
 165             }
 166           name->found = 1;
 167           /* Fall through.  */
 168         case HEADER_SUCCESS_EXTENDED:
 169           logical_status = status;
 170           break;
 171
 172         case HEADER_ZERO_BLOCK:
 173           if (ignore_zeros_option)
 174             {
 175               set_next_block_after (current_header);
 176               break;
 177             }
 178           /* Fall through.  */
 179         case HEADER_END_OF_FILE:
 180           logical_status = HEADER_END_OF_FILE;
 181           break;
 182
 183         case HEADER_FAILURE:
 184           set_next_block_after (current_header);
 185           switch (previous_status)
 186             {
 187             case HEADER_STILL_UNREAD:
 188               WARN ((0, 0, _("This does not look like a tar archive")));
 189               /* Fall through.  */
 190
 191             case HEADER_SUCCESS:
 192             case HEADER_ZERO_BLOCK:
 193               ERROR ((0, 0, _("Skipping to next header")));
 194               /* Fall through.  */
 195
 196             case HEADER_FAILURE:
 197               break;
 198
 199             case HEADER_END_OF_FILE:
 200               abort ();
 201             }
 202           break;
 203         }
 204
 205       previous_status = status;
 206     }
 207   while (logical_status == HEADER_STILL_UNREAD);
 208
 209   records_skipped = records_read - 1;
 210   new_record = xmalloc (record_size);
 211
 212   if (logical_status == HEADER_SUCCESS
 213       || logical_status == HEADER_SUCCESS_EXTENDED)
 214     {
 215       write_archive_to_stdout = 0;
 216
 217       /* Save away blocks before this one in this record.  */
 218
 219       new_blocks = current_block - record_start;
 220       if (new_blocks)
 221         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 222
 223       if (logical_status == HEADER_SUCCESS)
 224         {
 225           /* FIXME: Pheew!  This is crufty code!  */
 226           logical_status = HEADER_STILL_UNREAD;
 227           goto flush_file;
 228         }
 229
 230       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 231          "delete.c", line 223: warning: loop not entered at top
 232          Reported by Bruno Haible.  */
 233       while (1)
 234         {
 235           enum read_header status;
 236
 237           /* Fill in a record.  */
 238
 239           if (current_block == record_end)
 240             flush_archive ();
 241           status = read_header (0);
 242
 243           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 244             {
 245               set_next_block_after (current_header);
 246               continue;
 247             }
 248           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 249             {
 250               logical_status = HEADER_END_OF_FILE;
 251               break;
 252             }
 253
 254           if (status == HEADER_FAILURE)
 255             {
 256               ERROR ((0, 0, _("Deleting non-header from archive")));
 257               set_next_block_after (current_header);
 258               continue;
 259             }
 260
 261           /* Found another header.  */
 262
 263           if (name = name_scan (current_stat_info.file_name), name)
 264             {
 265               name->found = 1;
 266             flush_file:
 267               set_next_block_after (current_header);
 268               blocks_to_skip = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 269
 270               while (record_end - current_block <= blocks_to_skip)
 271                 {
 272                   blocks_to_skip -= (record_end - current_block);
 273                   flush_archive ();
 274                 }
 275               current_block += blocks_to_skip;
 276               blocks_to_skip = 0;
 277               continue;
 278             }
 279
 280           /* Copy header.  */
 281
 282           write_recent_blocks (recent_long_name, recent_long_name_blocks);
 283           write_recent_blocks (recent_long_link, recent_long_link_blocks);
 284           new_record[new_blocks] = *current_header;
 285           new_blocks++;
 286           blocks_to_keep
 287             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 288           set_next_block_after (current_header);
 289           if (new_blocks == blocking_factor)
 290             write_record (1);
 291
 292           /* Copy data.  */
 293
 294           kept_blocks_in_record = record_end - current_block;
 295           if (kept_blocks_in_record > blocks_to_keep)
 296             kept_blocks_in_record = blocks_to_keep;
 297
 298           while (blocks_to_keep)
 299             {
 300               int count;
 301
 302               if (current_block == record_end)
 303                 {
 304                   flush_read ();
 305                   current_block = record_start;
 306                   kept_blocks_in_record = blocking_factor;
 307                   if (kept_blocks_in_record > blocks_to_keep)
 308                     kept_blocks_in_record = blocks_to_keep;
 309                 }
 310               count = kept_blocks_in_record;
 311               if (blocking_factor - new_blocks < count)
 312                 count = blocking_factor - new_blocks;
 313
 314               if (! count)
 315                 abort ();
 316
 317               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 318               new_blocks += count;
 319               current_block += count;
 320               blocks_to_keep -= count;
 321               kept_blocks_in_record -= count;
 322
 323               if (new_blocks == blocking_factor)
 324                 write_record (1);
 325             }
 326         }
 327     }
 328
 329   if (logical_status == HEADER_END_OF_FILE)
 330     {
 331       /* Write the end of tape.  FIXME: we can't use write_eot here,
 332          as it gets confused when the input is at end of file.  */
 333
 334       int total_zero_blocks = 0;
 335
 336       do
 337         {
 338           int zero_blocks = blocking_factor - new_blocks;
 339           memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 340           total_zero_blocks += zero_blocks;
 341           write_record (total_zero_blocks < 2);
 342         }
 343       while (total_zero_blocks < 2);
 344     }
 345
 346   free (new_record);
 347
 348   if (! acting_as_filter && ! _isrmt (archive))
 349     {
 350 #if MSDOS
 351       int status = write (archive, "", 0);
 352 #else
 353       off_t pos = lseek (archive, (off_t) 0, SEEK_CUR);
 354       int status = pos < 0 ? -1 : ftruncate (archive, pos);
 355 #endif
 356       if (status != 0)
 357         truncate_warn (archive_name_array[0]);
 358     }
 359
 360   close_archive ();
 361   names_notfound ();
 362 }