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, 2010 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 (&current_header,
 169                                              &current_stat_info,
 170                                              read_header_x_raw);
 171
 172       switch (status)
 173         {
 174         case HEADER_STILL_UNREAD:
 175           abort ();
 176
 177         case HEADER_SUCCESS:
 178           if ((name = name_scan (current_stat_info.file_name)) == NULL)
 179             {
 180               skip_member ();
 181               break;
 182             }
 183           name->found_count++;
 184           if (!ISFOUND(name))
 185             {
 186               skip_member ();
 187               break;
 188             }
 189
 190           /* Fall through.  */
 191         case HEADER_SUCCESS_EXTENDED:
 192           logical_status = status;
 193           break;
 194
 195         case HEADER_ZERO_BLOCK:
 196           if (ignore_zeros_option)
 197             {
 198               set_next_block_after (current_header);
 199               break;
 200             }
 201           /* Fall through.  */
 202         case HEADER_END_OF_FILE:
 203           logical_status = HEADER_END_OF_FILE;
 204           break;
 205
 206         case HEADER_FAILURE:
 207           set_next_block_after (current_header);
 208           switch (previous_status)
 209             {
 210             case HEADER_STILL_UNREAD:
 211               WARN ((0, 0, _("This does not look like a tar archive")));
 212               /* Fall through.  */
 213
 214             case HEADER_SUCCESS:
 215             case HEADER_SUCCESS_EXTENDED:
 216             case HEADER_ZERO_BLOCK:
 217               ERROR ((0, 0, _("Skipping to next header")));
 218               /* Fall through.  */
 219
 220             case HEADER_FAILURE:
 221               break;
 222
 223             case HEADER_END_OF_FILE:
 224               abort ();
 225             }
 226           break;
 227         }
 228
 229       previous_status = status;
 230     }
 231   while (logical_status == HEADER_STILL_UNREAD);
 232
 233   records_skipped = records_read - 1;
 234   new_record = xmalloc (record_size);
 235
 236   if (logical_status == HEADER_SUCCESS
 237       || logical_status == HEADER_SUCCESS_EXTENDED)
 238     {
 239       write_archive_to_stdout = false;
 240
 241       /* Save away blocks before this one in this record.  */
 242
 243       new_blocks = current_block - record_start;
 244       if (new_blocks)
 245         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 246
 247       if (logical_status == HEADER_SUCCESS)
 248         {
 249           /* FIXME: Pheew!  This is crufty code!  */
 250           logical_status = HEADER_STILL_UNREAD;
 251           goto flush_file;
 252         }
 253
 254       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 255          "delete.c", line 223: warning: loop not entered at top
 256          Reported by Bruno Haible.  */
 257       while (1)
 258         {
 259           enum read_header status;
 260
 261           /* Fill in a record.  */
 262
 263           if (current_block == record_end)
 264             flush_archive ();
 265           status = read_header (&current_header, &current_stat_info,
 266                                 read_header_auto);
 267
 268           xheader_decode (&current_stat_info);
 269
 270           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 271             {
 272               set_next_block_after (current_header);
 273               continue;
 274             }
 275           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 276             {
 277               logical_status = HEADER_END_OF_FILE;
 278               break;
 279             }
 280
 281           if (status == HEADER_FAILURE)
 282             {
 283               ERROR ((0, 0, _("Deleting non-header from archive")));
 284               set_next_block_after (current_header);
 285               continue;
 286             }
 287
 288           /* Found another header.  */
 289
 290           if ((name = name_scan (current_stat_info.file_name)) != NULL)
 291             {
 292               name->found_count++;
 293               if (ISFOUND(name))
 294                 {
 295                 flush_file:
 296                   set_next_block_after (current_header);
 297                   blocks_to_skip = (current_stat_info.stat.st_size
 298                                     + BLOCKSIZE - 1) / BLOCKSIZE;
 299
 300                   while (record_end - current_block <= blocks_to_skip)
 301                     {
 302                       blocks_to_skip -= (record_end - current_block);
 303                       flush_archive ();
 304                     }
 305                   current_block += blocks_to_skip;
 306                   blocks_to_skip = 0;
 307                   continue;
 308                 }
 309             }
 310           /* Copy header.  */
 311
 312           if (current_stat_info.xhdr.size)
 313             {
 314               write_recent_bytes (current_stat_info.xhdr.buffer,
 315                                   current_stat_info.xhdr.size);
 316             }
 317           else
 318             {
 319               write_recent_blocks (recent_long_name, recent_long_name_blocks);
 320               write_recent_blocks (recent_long_link, recent_long_link_blocks);
 321             }
 322           new_record[new_blocks] = *current_header;
 323           new_blocks++;
 324           blocks_to_keep
 325             = (current_stat_info.stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 326           set_next_block_after (current_header);
 327           if (new_blocks == blocking_factor)
 328             write_record (1);
 329
 330           /* Copy data.  */
 331
 332           kept_blocks_in_record = record_end - current_block;
 333           if (kept_blocks_in_record > blocks_to_keep)
 334             kept_blocks_in_record = blocks_to_keep;
 335
 336           while (blocks_to_keep)
 337             {
 338               int count;
 339
 340               if (current_block == record_end)
 341                 {
 342                   flush_read ();
 343                   current_block = record_start;
 344                   kept_blocks_in_record = blocking_factor;
 345                   if (kept_blocks_in_record > blocks_to_keep)
 346                     kept_blocks_in_record = blocks_to_keep;
 347                 }
 348               count = kept_blocks_in_record;
 349               if (blocking_factor - new_blocks < count)
 350                 count = blocking_factor - new_blocks;
 351
 352               if (! count)
 353                 abort ();
 354
 355               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 356               new_blocks += count;
 357               current_block += count;
 358               blocks_to_keep -= count;
 359               kept_blocks_in_record -= count;
 360
 361               if (new_blocks == blocking_factor)
 362                 write_record (1);
 363             }
 364         }
 365
 366       if (logical_status == HEADER_END_OF_FILE)
 367         {
 368           /* Write the end of tape.  FIXME: we can't use write_eot here,
 369              as it gets confused when the input is at end of file.  */
 370
 371           int total_zero_blocks = 0;
 372
 373           do
 374             {
 375               int zero_blocks = blocking_factor - new_blocks;
 376               memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 377               total_zero_blocks += zero_blocks;
 378               write_record (total_zero_blocks < 2);
 379             }
 380           while (total_zero_blocks < 2);
 381         }
 382
 383       if (! acting_as_filter && ! _isrmt (archive))
 384         {
 385           if (sys_truncate (archive))
 386             truncate_warn (archive_name_array[0]);
 387         }
 388     }
 389   free (new_record);
 390
 391   close_archive ();
 392   names_notfound ();
 393 }