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   1 /* Delete entries from a tar archive.
   2
   3    Copyright 1988, 1992, 1994, 1996-1997, 2000-2001, 2003-2006, 2010,
   4    2013-2014, 2016 Free Software Foundation, Inc.
   5
   6    This file is part of GNU tar.
   7
   8    GNU tar is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    GNU tar is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <system.h>
  22 #include <system-ioctl.h>
  23
  24 #include "common.h"
  25 #include <rmt.h>
  26
  27 static union block *new_record;
  28 static int new_blocks;
  29 static bool acting_as_filter;
  30
  31 /* FIXME: This module should not directly handle the following
  32    variables, instead, the interface should be cleaned up.  */
  33 extern union block *record_start;
  34 extern union block *record_end;
  35 extern union block *current_block;
  36 extern union block *recent_long_name;
  37 extern union block *recent_long_link;
  38 extern off_t records_read;
  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 (&current_header,
 170                                              &current_stat_info,
 171                                              read_header_x_raw);
 172
 173       switch (status)
 174         {
 175         case HEADER_STILL_UNREAD:
 176           abort ();
 177
 178         case HEADER_SUCCESS:
 179           if ((name = name_scan (current_stat_info.file_name)) == NULL)
 180             {
 181               skip_member ();
 182               break;
 183             }
 184           name->found_count++;
 185           if (!ISFOUND(name))
 186             {
 187               skip_member ();
 188               break;
 189             }
 190
 191           /* Fall through.  */
 192         case HEADER_SUCCESS_EXTENDED:
 193           logical_status = status;
 194           break;
 195
 196         case HEADER_ZERO_BLOCK:
 197           if (ignore_zeros_option)
 198             {
 199               set_next_block_after (current_header);
 200               break;
 201             }
 202           /* Fall through.  */
 203         case HEADER_END_OF_FILE:
 204           logical_status = HEADER_END_OF_FILE;
 205           break;
 206
 207         case HEADER_FAILURE:
 208           set_next_block_after (current_header);
 209           switch (previous_status)
 210             {
 211             case HEADER_STILL_UNREAD:
 212               WARN ((0, 0, _("This does not look like a tar archive")));
 213               /* Fall through.  */
 214
 215             case HEADER_SUCCESS:
 216             case HEADER_SUCCESS_EXTENDED:
 217             case HEADER_ZERO_BLOCK:
 218               ERROR ((0, 0, _("Skipping to next header")));
 219               /* Fall through.  */
 220
 221             case HEADER_FAILURE:
 222               break;
 223
 224             case HEADER_END_OF_FILE:
 225               abort ();
 226             }
 227           break;
 228         }
 229
 230       previous_status = status;
 231     }
 232   while (logical_status == HEADER_STILL_UNREAD);
 233
 234   records_skipped = records_read - 1;
 235   new_record = xmalloc (record_size);
 236
 237   if (logical_status == HEADER_SUCCESS
 238       || logical_status == HEADER_SUCCESS_EXTENDED)
 239     {
 240       write_archive_to_stdout = false;
 241
 242       /* Save away blocks before this one in this record.  */
 243
 244       new_blocks = current_block - record_start;
 245       if (new_blocks)
 246         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 247
 248       if (logical_status == HEADER_SUCCESS)
 249         {
 250           /* FIXME: Pheew!  This is crufty code!  */
 251           logical_status = HEADER_STILL_UNREAD;
 252           goto flush_file;
 253         }
 254
 255       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 256          "delete.c", line 223: warning: loop not entered at top
 257          Reported by Bruno Haible.  */
 258       while (1)
 259         {
 260           enum read_header status;
 261
 262           /* Fill in a record.  */
 263
 264           if (current_block == record_end)
 265             flush_archive ();
 266           status = read_header (&current_header, &current_stat_info,
 267                                 read_header_auto);
 268
 269           xheader_decode (&current_stat_info);
 270
 271           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 272             {
 273               set_next_block_after (current_header);
 274               continue;
 275             }
 276           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 277             {
 278               logical_status = HEADER_END_OF_FILE;
 279               break;
 280             }
 281
 282           if (status == HEADER_FAILURE)
 283             {
 284               ERROR ((0, 0, _("Deleting non-header from archive")));
 285               set_next_block_after (current_header);
 286               continue;
 287             }
 288
 289           /* Found another header.  */
 290
 291           if ((name = name_scan (current_stat_info.file_name)) != NULL)
 292             {
 293               name->found_count++;
 294               if (ISFOUND(name))
 295                 {
 296                 flush_file:
 297                   set_next_block_after (current_header);
 298                   blocks_to_skip = (current_stat_info.stat.st_size
 299                                     + BLOCKSIZE - 1) / BLOCKSIZE;
 300
 301                   while (record_end - current_block <= blocks_to_skip)
 302                     {
 303                       blocks_to_skip -= (record_end - current_block);
 304                       flush_archive ();
 305                     }
 306                   current_block += blocks_to_skip;
 307                   blocks_to_skip = 0;
 308                   continue;
 309                 }
 310             }
 311           /* Copy header.  */
 312
 313           if (current_stat_info.xhdr.size)
 314             {
 315               write_recent_bytes (current_stat_info.xhdr.buffer,
 316                                   current_stat_info.xhdr.size);
 317             }
 318           else
 319             {
 320               write_recent_blocks (recent_long_name, recent_long_name_blocks);
 321               write_recent_blocks (recent_long_link, recent_long_link_blocks);
 322             }
 323           new_record[new_blocks] = *current_header;
 324           new_blocks++;
 325           blocks_to_keep
 326             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 327           set_next_block_after (current_header);
 328           if (new_blocks == blocking_factor)
 329             write_record (1);
 330
 331           /* Copy data.  */
 332
 333           kept_blocks_in_record = record_end - current_block;
 334           if (kept_blocks_in_record > blocks_to_keep)
 335             kept_blocks_in_record = blocks_to_keep;
 336
 337           while (blocks_to_keep)
 338             {
 339               int count;
 340
 341               if (current_block == record_end)
 342                 {
 343                   flush_read ();
 344                   current_block = record_start;
 345                   kept_blocks_in_record = blocking_factor;
 346                   if (kept_blocks_in_record > blocks_to_keep)
 347                     kept_blocks_in_record = blocks_to_keep;
 348                 }
 349               count = kept_blocks_in_record;
 350               if (blocking_factor - new_blocks < count)
 351                 count = blocking_factor - new_blocks;
 352
 353               if (! count)
 354                 abort ();
 355
 356               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 357               new_blocks += count;
 358               current_block += count;
 359               blocks_to_keep -= count;
 360               kept_blocks_in_record -= count;
 361
 362               if (new_blocks == blocking_factor)
 363                 write_record (1);
 364             }
 365         }
 366
 367       if (logical_status == HEADER_END_OF_FILE)
 368         {
 369           /* Write the end of tape.  FIXME: we can't use write_eot here,
 370              as it gets confused when the input is at end of file.  */
 371
 372           int total_zero_blocks = 0;
 373
 374           do
 375             {
 376               int zero_blocks = blocking_factor - new_blocks;
 377               memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 378               total_zero_blocks += zero_blocks;
 379               write_record (total_zero_blocks < 2);
 380             }
 381           while (total_zero_blocks < 2);
 382         }
 383
 384       if (! acting_as_filter && ! _isrmt (archive))
 385         {
 386           if (sys_truncate (archive))
 387             truncate_warn (archive_name_array[0]);
 388         }
 389     }
 390   free (new_record);
 391
 392   close_archive ();
 393   names_notfound ();
 394 }