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 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 #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 extern off_t records_written;
  39
  40 /* The number of records skipped at the start of the archive, when
  41    passing over members that are not deleted.  */
  42 off_t records_skipped;
  43
  44 /* Move archive descriptor by COUNT records worth.  If COUNT is
  45    positive we move forward, else we move negative.  If it's a tape,
  46    MTIOCTOP had better work.  If it's something else, we try to seek
  47    on it.  If we can't seek, we lose!  */
  48 static void
  49 move_archive (off_t count)
  50 {
  51   if (count == 0)
  52     return;
  53
  54 #ifdef MTIOCTOP
  55   {
  56     struct mtop operation;
  57
  58     if (count < 0
  59         ? (operation.mt_op = MTBSR,
  60            operation.mt_count = -count,
  61            operation.mt_count == -count)
  62         : (operation.mt_op = MTFSR,
  63            operation.mt_count = count,
  64            operation.mt_count == count))
  65       {
  66         if (0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  67           return;
  68
  69         if (errno == EIO
  70             && 0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  71           return;
  72       }
  73   }
  74 #endif /* MTIOCTOP */
  75
  76   {
  77     off_t position0 = rmtlseek (archive, (off_t) 0, SEEK_CUR);
  78     off_t increment = record_size * (off_t) count;
  79     off_t position = position0 + increment;
  80
  81     if (increment / count != record_size
  82         || (position < position0) != (increment < 0)
  83         || (position = position < 0 ? 0 : position,
  84             rmtlseek (archive, position, SEEK_SET) != position))
  85       seek_error_details (archive_name_array[0], position);
  86
  87     return;
  88   }
  89 }
  90
  91 /* Write out the record which has been filled.  If MOVE_BACK_FLAG,
  92    backspace to where we started.  */
  93 static void
  94 write_record (int move_back_flag)
  95 {
  96   union block *save_record = record_start;
  97   record_start = new_record;
  98
  99   if (acting_as_filter)
 100     {
 101       archive = STDOUT_FILENO;
 102       flush_write ();
 103       archive = STDIN_FILENO;
 104     }
 105   else
 106     {
 107       move_archive ((records_written + records_skipped) - records_read);
 108       flush_write ();
 109     }
 110
 111   record_start = save_record;
 112
 113   if (move_back_flag)
 114     {
 115       /* Move the tape head back to where we were.  */
 116
 117       if (! acting_as_filter)
 118         move_archive (records_read - (records_written + records_skipped));
 119     }
 120
 121   new_blocks = 0;
 122 }
 123
 124 static void
 125 write_recent_blocks (union block *h, size_t blocks)
 126 {
 127   size_t i;
 128   for (i = 0; i < blocks; i++)
 129     {
 130       new_record[new_blocks++] = h[i];
 131       if (new_blocks == blocking_factor)
 132         write_record (1);
 133     }
 134 }
 135
 136 static void
 137 write_recent_bytes (char *data, size_t bytes)
 138 {
 139   size_t blocks = bytes / BLOCKSIZE;
 140   size_t rest = bytes - blocks * BLOCKSIZE;
 141
 142   write_recent_blocks ((union block *)data, blocks);
 143   memcpy (new_record[new_blocks].buffer, data + blocks * BLOCKSIZE, rest);
 144   if (rest < BLOCKSIZE)
 145     memset (new_record[new_blocks].buffer + rest, 0, BLOCKSIZE - rest);
 146   new_blocks++;
 147   if (new_blocks == blocking_factor)
 148     write_record (1);
 149 }
 150
 151 void
 152 delete_archive_members (void)
 153 {
 154   enum read_header logical_status = HEADER_STILL_UNREAD;
 155   enum read_header previous_status = HEADER_STILL_UNREAD;
 156
 157   /* FIXME: Should clean the routine before cleaning these variables :-( */
 158   struct name *name;
 159   off_t blocks_to_skip = 0;
 160   off_t blocks_to_keep = 0;
 161   int kept_blocks_in_record;
 162
 163   name_gather ();
 164   open_archive (ACCESS_UPDATE);
 165   acting_as_filter = strcmp (archive_name_array[0], "-") == 0;
 166
 167   do
 168     {
 169       enum read_header status = read_header (true);
 170
 171       switch (status)
 172         {
 173         case HEADER_STILL_UNREAD:
 174           abort ();
 175
 176         case HEADER_SUCCESS:
 177           if ((name = name_scan (current_stat_info.file_name, false)) == NULL)
 178             {
 179               skip_member ();
 180               break;
 181             }
 182           name->found_count++;
 183           if (!ISFOUND(name))
 184             {
 185               skip_member ();
 186               break;
 187             }
 188
 189           /* Fall through.  */
 190         case HEADER_SUCCESS_EXTENDED:
 191           logical_status = status;
 192           break;
 193
 194         case HEADER_ZERO_BLOCK:
 195           if (ignore_zeros_option)
 196             {
 197               set_next_block_after (current_header);
 198               break;
 199             }
 200           /* Fall through.  */
 201         case HEADER_END_OF_FILE:
 202           logical_status = HEADER_END_OF_FILE;
 203           break;
 204
 205         case HEADER_FAILURE:
 206           set_next_block_after (current_header);
 207           switch (previous_status)
 208             {
 209             case HEADER_STILL_UNREAD:
 210               WARN ((0, 0, _("This does not look like a tar archive")));
 211               /* Fall through.  */
 212
 213             case HEADER_SUCCESS:
 214             case HEADER_SUCCESS_EXTENDED:
 215             case HEADER_ZERO_BLOCK:
 216               ERROR ((0, 0, _("Skipping to next header")));
 217               /* Fall through.  */
 218
 219             case HEADER_FAILURE:
 220               break;
 221
 222             case HEADER_END_OF_FILE:
 223               abort ();
 224             }
 225           break;
 226         }
 227
 228       previous_status = status;
 229     }
 230   while (logical_status == HEADER_STILL_UNREAD);
 231
 232   records_skipped = records_read - 1;
 233   new_record = xmalloc (record_size);
 234
 235   if (logical_status == HEADER_SUCCESS
 236       || logical_status == HEADER_SUCCESS_EXTENDED)
 237     {
 238       write_archive_to_stdout = false;
 239
 240       /* Save away blocks before this one in this record.  */
 241
 242       new_blocks = current_block - record_start;
 243       if (new_blocks)
 244         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 245
 246       if (logical_status == HEADER_SUCCESS)
 247         {
 248           /* FIXME: Pheew!  This is crufty code!  */
 249           logical_status = HEADER_STILL_UNREAD;
 250           goto flush_file;
 251         }
 252
 253       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 254          "delete.c", line 223: warning: loop not entered at top
 255          Reported by Bruno Haible.  */
 256       while (1)
 257         {
 258           enum read_header status;
 259
 260           /* Fill in a record.  */
 261
 262           if (current_block == record_end)
 263             flush_archive ();
 264           status = read_header (false);
 265
 266           xheader_decode (&current_stat_info);
 267
 268           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 269             {
 270               set_next_block_after (current_header);
 271               continue;
 272             }
 273           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 274             {
 275               logical_status = HEADER_END_OF_FILE;
 276               break;
 277             }
 278
 279           if (status == HEADER_FAILURE)
 280             {
 281               ERROR ((0, 0, _("Deleting non-header from archive")));
 282               set_next_block_after (current_header);
 283               continue;
 284             }
 285
 286           /* Found another header.  */
 287
 288           if ((name = name_scan (current_stat_info.file_name, false)) != NULL)
 289             {
 290               name->found_count++;
 291               if (ISFOUND(name))
 292                 {
 293                 flush_file:
 294                   set_next_block_after (current_header);
 295                   blocks_to_skip = (current_stat_info.stat.st_size
 296                                     + BLOCKSIZE - 1) / BLOCKSIZE;
 297
 298                   while (record_end - current_block <= blocks_to_skip)
 299                     {
 300                       blocks_to_skip -= (record_end - current_block);
 301                       flush_archive ();
 302                     }
 303                   current_block += blocks_to_skip;
 304                   blocks_to_skip = 0;
 305                   continue;
 306                 }
 307             }
 308           /* Copy header.  */
 309
 310           if (extended_header.size)
 311             {
 312               write_recent_bytes (extended_header.buffer,
 313                                   extended_header.size);
 314             }
 315           else
 316             {
 317               write_recent_blocks (recent_long_name, recent_long_name_blocks);
 318               write_recent_blocks (recent_long_link, recent_long_link_blocks);
 319             }
 320           new_record[new_blocks] = *current_header;
 321           new_blocks++;
 322           blocks_to_keep
 323             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 324           set_next_block_after (current_header);
 325           if (new_blocks == blocking_factor)
 326             write_record (1);
 327
 328           /* Copy data.  */
 329
 330           kept_blocks_in_record = record_end - current_block;
 331           if (kept_blocks_in_record > blocks_to_keep)
 332             kept_blocks_in_record = blocks_to_keep;
 333
 334           while (blocks_to_keep)
 335             {
 336               int count;
 337
 338               if (current_block == record_end)
 339                 {
 340                   flush_read ();
 341                   current_block = record_start;
 342                   kept_blocks_in_record = blocking_factor;
 343                   if (kept_blocks_in_record > blocks_to_keep)
 344                     kept_blocks_in_record = blocks_to_keep;
 345                 }
 346               count = kept_blocks_in_record;
 347               if (blocking_factor - new_blocks < count)
 348                 count = blocking_factor - new_blocks;
 349
 350               if (! count)
 351                 abort ();
 352
 353               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 354               new_blocks += count;
 355               current_block += count;
 356               blocks_to_keep -= count;
 357               kept_blocks_in_record -= count;
 358
 359               if (new_blocks == blocking_factor)
 360                 write_record (1);
 361             }
 362         }
 363
 364       if (logical_status == HEADER_END_OF_FILE)
 365         {
 366           /* Write the end of tape.  FIXME: we can't use write_eot here,
 367              as it gets confused when the input is at end of file.  */
 368
 369           int total_zero_blocks = 0;
 370
 371           do
 372             {
 373               int zero_blocks = blocking_factor - new_blocks;
 374               memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 375               total_zero_blocks += zero_blocks;
 376               write_record (total_zero_blocks < 2);
 377             }
 378           while (total_zero_blocks < 2);
 379         }
 380
 381       if (! acting_as_filter && ! _isrmt (archive))
 382         {
 383           if (sys_truncate (archive))
 384             truncate_warn (archive_name_array[0]);
 385         }
 386     }
 387   free (new_record);
 388
 389   close_archive ();
 390   names_notfound ();
 391 }