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 static void
 136 write_recent_bytes (char *data, size_t bytes)
 137 {
 138   size_t blocks = bytes / BLOCKSIZE;
 139   size_t rest = bytes - blocks * BLOCKSIZE;
 140
 141   write_recent_blocks ((union block *)data, blocks);
 142   memcpy (new_record[new_blocks].buffer, data + blocks * BLOCKSIZE, rest);
 143   if (rest < BLOCKSIZE)
 144     memset (new_record[new_blocks].buffer + rest, 0, BLOCKSIZE - rest);
 145   new_blocks++;
 146   if (new_blocks == blocking_factor)
 147     write_record (1);
 148 }
 149
 150 void
 151 delete_archive_members (void)
 152 {
 153   enum read_header logical_status = HEADER_STILL_UNREAD;
 154   enum read_header previous_status = HEADER_STILL_UNREAD;
 155
 156   /* FIXME: Should clean the routine before cleaning these variables :-( */
 157   struct name *name;
 158   off_t blocks_to_skip = 0;
 159   off_t blocks_to_keep = 0;
 160   int kept_blocks_in_record;
 161
 162   name_gather ();
 163   open_archive (ACCESS_UPDATE);
 164   acting_as_filter = strcmp (archive_name_array[0], "-") == 0;
 165
 166   do
 167     {
 168       enum read_header status = read_header (true);
 169
 170       switch (status)
 171         {
 172         case HEADER_STILL_UNREAD:
 173           abort ();
 174
 175         case HEADER_SUCCESS:
 176           if (name = name_scan (current_stat_info.file_name), !name)
 177             {
 178               skip_member ();
 179               break;
 180             }
 181           name->found = 1;
 182           /* Fall through.  */
 183         case HEADER_SUCCESS_EXTENDED:
 184           logical_status = status;
 185           break;
 186
 187         case HEADER_ZERO_BLOCK:
 188           if (ignore_zeros_option)
 189             {
 190               set_next_block_after (current_header);
 191               break;
 192             }
 193           /* Fall through.  */
 194         case HEADER_END_OF_FILE:
 195           logical_status = HEADER_END_OF_FILE;
 196           break;
 197
 198         case HEADER_FAILURE:
 199           set_next_block_after (current_header);
 200           switch (previous_status)
 201             {
 202             case HEADER_STILL_UNREAD:
 203               WARN ((0, 0, _("This does not look like a tar archive")));
 204               /* Fall through.  */
 205
 206             case HEADER_SUCCESS:
 207             case HEADER_SUCCESS_EXTENDED:
 208             case HEADER_ZERO_BLOCK:
 209               ERROR ((0, 0, _("Skipping to next header")));
 210               /* Fall through.  */
 211
 212             case HEADER_FAILURE:
 213               break;
 214
 215             case HEADER_END_OF_FILE:
 216               abort ();
 217             }
 218           break;
 219         }
 220
 221       previous_status = status;
 222     }
 223   while (logical_status == HEADER_STILL_UNREAD);
 224
 225   records_skipped = records_read - 1;
 226   new_record = xmalloc (record_size);
 227
 228   if (logical_status == HEADER_SUCCESS
 229       || logical_status == HEADER_SUCCESS_EXTENDED)
 230     {
 231       write_archive_to_stdout = 0;
 232
 233       /* Save away blocks before this one in this record.  */
 234
 235       new_blocks = current_block - record_start;
 236       if (new_blocks)
 237         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 238
 239       if (logical_status == HEADER_SUCCESS)
 240         {
 241           /* FIXME: Pheew!  This is crufty code!  */
 242           logical_status = HEADER_STILL_UNREAD;
 243           goto flush_file;
 244         }
 245
 246       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 247          "delete.c", line 223: warning: loop not entered at top
 248          Reported by Bruno Haible.  */
 249       while (1)
 250         {
 251           enum read_header status;
 252
 253           /* Fill in a record.  */
 254
 255           if (current_block == record_end)
 256             flush_archive ();
 257           status = read_header (false);
 258
 259           if (extended_header.size)
 260             xheader_decode (&current_stat_info);
 261
 262           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 263             {
 264               set_next_block_after (current_header);
 265               continue;
 266             }
 267           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 268             {
 269               logical_status = HEADER_END_OF_FILE;
 270               break;
 271             }
 272
 273           if (status == HEADER_FAILURE)
 274             {
 275               ERROR ((0, 0, _("Deleting non-header from archive")));
 276               set_next_block_after (current_header);
 277               continue;
 278             }
 279
 280           /* Found another header.  */
 281
 282           if (name = name_scan (current_stat_info.file_name), name)
 283             {
 284               name->found = 1;
 285             flush_file:
 286               set_next_block_after (current_header);
 287               blocks_to_skip = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 288
 289               while (record_end - current_block <= blocks_to_skip)
 290                 {
 291                   blocks_to_skip -= (record_end - current_block);
 292                   flush_archive ();
 293                 }
 294               current_block += blocks_to_skip;
 295               blocks_to_skip = 0;
 296               continue;
 297             }
 298
 299           /* Copy header.  */
 300
 301           if (extended_header.size)
 302             {
 303               write_recent_bytes (extended_header.buffer,
 304                                   extended_header.size);
 305             }
 306           else
 307             {
 308               write_recent_blocks (recent_long_name, recent_long_name_blocks);
 309               write_recent_blocks (recent_long_link, recent_long_link_blocks);
 310             }
 311           new_record[new_blocks] = *current_header;
 312           new_blocks++;
 313           blocks_to_keep
 314             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 315           set_next_block_after (current_header);
 316           if (new_blocks == blocking_factor)
 317             write_record (1);
 318
 319           /* Copy data.  */
 320
 321           kept_blocks_in_record = record_end - current_block;
 322           if (kept_blocks_in_record > blocks_to_keep)
 323             kept_blocks_in_record = blocks_to_keep;
 324
 325           while (blocks_to_keep)
 326             {
 327               int count;
 328
 329               if (current_block == record_end)
 330                 {
 331                   flush_read ();
 332                   current_block = record_start;
 333                   kept_blocks_in_record = blocking_factor;
 334                   if (kept_blocks_in_record > blocks_to_keep)
 335                     kept_blocks_in_record = blocks_to_keep;
 336                 }
 337               count = kept_blocks_in_record;
 338               if (blocking_factor - new_blocks < count)
 339                 count = blocking_factor - new_blocks;
 340
 341               if (! count)
 342                 abort ();
 343
 344               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 345               new_blocks += count;
 346               current_block += count;
 347               blocks_to_keep -= count;
 348               kept_blocks_in_record -= count;
 349
 350               if (new_blocks == blocking_factor)
 351                 write_record (1);
 352             }
 353         }
 354     }
 355
 356   if (logical_status == HEADER_END_OF_FILE)
 357     {
 358       /* Write the end of tape.  FIXME: we can't use write_eot here,
 359          as it gets confused when the input is at end of file.  */
 360
 361       int total_zero_blocks = 0;
 362
 363       do
 364         {
 365           int zero_blocks = blocking_factor - new_blocks;
 366           memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 367           total_zero_blocks += zero_blocks;
 368           write_record (total_zero_blocks < 2);
 369         }
 370       while (total_zero_blocks < 2);
 371     }
 372
 373   free (new_record);
 374
 375   if (! acting_as_filter && ! _isrmt (archive))
 376     {
 377 #if MSDOS
 378       int status = write (archive, "", 0);
 379 #else
 380       off_t pos = lseek (archive, (off_t) 0, SEEK_CUR);
 381       int status = pos < 0 ? -1 : ftruncate (archive, pos);
 382 #endif
 383       if (status != 0)
 384         truncate_warn (archive_name_array[0]);
 385     }
 386
 387   close_archive ();
 388   names_notfound ();
 389 }