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, 2004,
   4    2005, 2006 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 3, 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 #include <system.h>
  21 #include <system-ioctl.h>
  22
  23 #include "common.h"
  24 #include <rmt.h>
  25
  26 static union block *new_record;
  27 static int new_blocks;
  28 static bool acting_as_filter;
  29
  30 /* FIXME: This module should not directly handle the following
  31    variables, instead, the interface should be cleaned up.  */
  32 extern union block *record_start;
  33 extern union block *record_end;
  34 extern union block *current_block;
  35 extern union block *recent_long_name;
  36 extern union block *recent_long_link;
  37 extern off_t records_read;
  38
  39 /* The number of records skipped at the start of the archive, when
  40    passing over members that are not deleted.  */
  41 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)) == NULL)
 177             {
 178               skip_member ();
 179               break;
 180             }
 181           name->found_count++;
 182           if (!ISFOUND(name))
 183             {
 184               skip_member ();
 185               break;
 186             }
 187
 188           /* Fall through.  */
 189         case HEADER_SUCCESS_EXTENDED:
 190           logical_status = status;
 191           break;
 192
 193         case HEADER_ZERO_BLOCK:
 194           if (ignore_zeros_option)
 195             {
 196               set_next_block_after (current_header);
 197               break;
 198             }
 199           /* Fall through.  */
 200         case HEADER_END_OF_FILE:
 201           logical_status = HEADER_END_OF_FILE;
 202           break;
 203
 204         case HEADER_FAILURE:
 205           set_next_block_after (current_header);
 206           switch (previous_status)
 207             {
 208             case HEADER_STILL_UNREAD:
 209               WARN ((0, 0, _("This does not look like a tar archive")));
 210               /* Fall through.  */
 211
 212             case HEADER_SUCCESS:
 213             case HEADER_SUCCESS_EXTENDED:
 214             case HEADER_ZERO_BLOCK:
 215               ERROR ((0, 0, _("Skipping to next header")));
 216               /* Fall through.  */
 217
 218             case HEADER_FAILURE:
 219               break;
 220
 221             case HEADER_END_OF_FILE:
 222               abort ();
 223             }
 224           break;
 225         }
 226
 227       previous_status = status;
 228     }
 229   while (logical_status == HEADER_STILL_UNREAD);
 230
 231   records_skipped = records_read - 1;
 232   new_record = xmalloc (record_size);
 233
 234   if (logical_status == HEADER_SUCCESS
 235       || logical_status == HEADER_SUCCESS_EXTENDED)
 236     {
 237       write_archive_to_stdout = false;
 238
 239       /* Save away blocks before this one in this record.  */
 240
 241       new_blocks = current_block - record_start;
 242       if (new_blocks)
 243         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 244
 245       if (logical_status == HEADER_SUCCESS)
 246         {
 247           /* FIXME: Pheew!  This is crufty code!  */
 248           logical_status = HEADER_STILL_UNREAD;
 249           goto flush_file;
 250         }
 251
 252       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 253          "delete.c", line 223: warning: loop not entered at top
 254          Reported by Bruno Haible.  */
 255       while (1)
 256         {
 257           enum read_header status;
 258
 259           /* Fill in a record.  */
 260
 261           if (current_block == record_end)
 262             flush_archive ();
 263           status = read_header (false);
 264
 265           xheader_decode (&current_stat_info);
 266
 267           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 268             {
 269               set_next_block_after (current_header);
 270               continue;
 271             }
 272           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 273             {
 274               logical_status = HEADER_END_OF_FILE;
 275               break;
 276             }
 277
 278           if (status == HEADER_FAILURE)
 279             {
 280               ERROR ((0, 0, _("Deleting non-header from archive")));
 281               set_next_block_after (current_header);
 282               continue;
 283             }
 284
 285           /* Found another header.  */
 286
 287           if ((name = name_scan (current_stat_info.file_name)) != NULL)
 288             {
 289               name->found_count++;
 290               if (ISFOUND(name))
 291                 {
 292                 flush_file:
 293                   set_next_block_after (current_header);
 294                   blocks_to_skip = (current_stat_info.stat.st_size
 295                                     + BLOCKSIZE - 1) / BLOCKSIZE;
 296
 297                   while (record_end - current_block <= blocks_to_skip)
 298                     {
 299                       blocks_to_skip -= (record_end - current_block);
 300                       flush_archive ();
 301                     }
 302                   current_block += blocks_to_skip;
 303                   blocks_to_skip = 0;
 304                   continue;
 305                 }
 306             }
 307           /* Copy header.  */
 308
 309           if (current_stat_info.xhdr.size)
 310             {
 311               write_recent_bytes (current_stat_info.xhdr.buffer,
 312                                   current_stat_info.xhdr.size);
 313             }
 314           else
 315             {
 316               write_recent_blocks (recent_long_name, recent_long_name_blocks);
 317               write_recent_blocks (recent_long_link, recent_long_link_blocks);
 318             }
 319           new_record[new_blocks] = *current_header;
 320           new_blocks++;
 321           blocks_to_keep
 322             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 323           set_next_block_after (current_header);
 324           if (new_blocks == blocking_factor)
 325             write_record (1);
 326
 327           /* Copy data.  */
 328
 329           kept_blocks_in_record = record_end - current_block;
 330           if (kept_blocks_in_record > blocks_to_keep)
 331             kept_blocks_in_record = blocks_to_keep;
 332
 333           while (blocks_to_keep)
 334             {
 335               int count;
 336
 337               if (current_block == record_end)
 338                 {
 339                   flush_read ();
 340                   current_block = record_start;
 341                   kept_blocks_in_record = blocking_factor;
 342                   if (kept_blocks_in_record > blocks_to_keep)
 343                     kept_blocks_in_record = blocks_to_keep;
 344                 }
 345               count = kept_blocks_in_record;
 346               if (blocking_factor - new_blocks < count)
 347                 count = blocking_factor - new_blocks;
 348
 349               if (! count)
 350                 abort ();
 351
 352               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 353               new_blocks += count;
 354               current_block += count;
 355               blocks_to_keep -= count;
 356               kept_blocks_in_record -= count;
 357
 358               if (new_blocks == blocking_factor)
 359                 write_record (1);
 360             }
 361         }
 362
 363       if (logical_status == HEADER_END_OF_FILE)
 364         {
 365           /* Write the end of tape.  FIXME: we can't use write_eot here,
 366              as it gets confused when the input is at end of file.  */
 367
 368           int total_zero_blocks = 0;
 369
 370           do
 371             {
 372               int zero_blocks = blocking_factor - new_blocks;
 373               memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 374               total_zero_blocks += zero_blocks;
 375               write_record (total_zero_blocks < 2);
 376             }
 377           while (total_zero_blocks < 2);
 378         }
 379
 380       if (! acting_as_filter && ! _isrmt (archive))
 381         {
 382           if (sys_truncate (archive))
 383             truncate_warn (archive_name_array[0]);
 384         }
 385     }
 386   free (new_record);
 387
 388   close_archive ();
 389   names_notfound ();
 390 }