contrib/tar/src/delete.c

   1 /* Delete entries from a tar archive.
   2
   3    Copyright (C) 1988, 1992, 1994, 1996, 1997, 2000, 2001 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 size_t recent_long_name_blocks;
  37 extern size_t recent_long_link_blocks;
  38 extern off_t records_read;
  39 extern off_t records_written;
  40
  41 /* The number of records skipped at the start of the archive, when
  42    passing over members that are not deleted.  */
  43 static off_t records_skipped;
  44
  45 /* Move archive descriptor by COUNT records worth.  If COUNT is
  46    positive we move forward, else we move negative.  If it's a tape,
  47    MTIOCTOP had better work.  If it's something else, we try to seek
  48    on it.  If we can't seek, we lose!  */
  49 static void
  50 move_archive (off_t count)
  51 {
  52   if (count == 0)
  53     return;
  54
  55 #ifdef MTIOCTOP
  56   {
  57     struct mtop operation;
  58
  59     if (count < 0
  60         ? (operation.mt_op = MTBSR,
  61            operation.mt_count = -count,
  62            operation.mt_count == -count)
  63         : (operation.mt_op = MTFSR,
  64            operation.mt_count = count,
  65            operation.mt_count == count))
  66       {
  67         if (0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  68           return;
  69
  70         if (errno == EIO
  71             && 0 <= rmtioctl (archive, MTIOCTOP, (char *) &operation))
  72           return;
  73       }
  74   }
  75 #endif /* MTIOCTOP */
  76
  77   {
  78     off_t position0 = rmtlseek (archive, (off_t) 0, SEEK_CUR);
  79     off_t increment = record_size * (off_t) count;
  80     off_t position = position0 + increment;
  81
  82     if (increment / count != record_size
  83         || (position < position0) != (increment < 0)
  84         || (position = position < 0 ? 0 : position,
  85             rmtlseek (archive, position, SEEK_SET) != position))
  86       seek_error_details (archive_name_array[0], position);
  87
  88     return;
  89   }
  90 }
  91
  92 /* Write out the record which has been filled.  If MOVE_BACK_FLAG,
  93    backspace to where we started.  */
  94 static void
  95 write_record (int move_back_flag)
  96 {
  97   union block *save_record = record_start;
  98   record_start = new_record;
  99
 100   if (acting_as_filter)
 101     {
 102       archive = STDOUT_FILENO;
 103       flush_write ();
 104       archive = STDIN_FILENO;
 105     }
 106   else
 107     {
 108       move_archive ((records_written + records_skipped) - records_read);
 109       flush_write ();
 110     }
 111
 112   record_start = save_record;
 113
 114   if (move_back_flag)
 115     {
 116       /* Move the tape head back to where we were.  */
 117
 118       if (! acting_as_filter)
 119         move_archive (records_read - (records_written + records_skipped));
 120     }
 121
 122   new_blocks = 0;
 123 }
 124
 125 static void
 126 write_recent_blocks (union block *h, size_t blocks)
 127 {
 128   size_t i;
 129   for (i = 0; i < blocks; i++)
 130     {
 131       new_record[new_blocks++] = h[i];
 132       if (new_blocks == blocking_factor)
 133         write_record (1);
 134     }
 135 }
 136
 137 void
 138 delete_archive_members (void)
 139 {
 140   enum read_header logical_status = HEADER_STILL_UNREAD;
 141   enum read_header previous_status = HEADER_STILL_UNREAD;
 142
 143   /* FIXME: Should clean the routine before cleaning these variables :-( */
 144   struct name *name;
 145   off_t blocks_to_skip = 0;
 146   off_t blocks_to_keep = 0;
 147   int kept_blocks_in_record;
 148
 149   name_gather ();
 150   open_archive (ACCESS_UPDATE);
 151   acting_as_filter = strcmp (archive_name_array[0], "-") == 0;
 152
 153   do
 154     {
 155       enum read_header status = read_header (1);
 156
 157       switch (status)
 158         {
 159         case HEADER_STILL_UNREAD:
 160           abort ();
 161
 162         case HEADER_SUCCESS:
 163           if (name = name_scan (current_file_name), !name)
 164             {
 165               skip_member ();
 166               break;
 167             }
 168           name->found = 1;
 169           /* Fall through.  */
 170         case HEADER_SUCCESS_EXTENDED:
 171           logical_status = status;
 172           break;
 173
 174         case HEADER_ZERO_BLOCK:
 175           if (ignore_zeros_option)
 176             {
 177               set_next_block_after (current_header);
 178               break;
 179             }
 180           /* Fall through.  */
 181         case HEADER_END_OF_FILE:
 182           logical_status = HEADER_END_OF_FILE;
 183           break;
 184
 185         case HEADER_FAILURE:
 186           set_next_block_after (current_header);
 187           switch (previous_status)
 188             {
 189             case HEADER_STILL_UNREAD:
 190               WARN ((0, 0, _("This does not look like a tar archive")));
 191               /* Fall through.  */
 192
 193             case HEADER_SUCCESS:
 194             case HEADER_ZERO_BLOCK:
 195               ERROR ((0, 0, _("Skipping to next header")));
 196               /* Fall through.  */
 197
 198             case HEADER_FAILURE:
 199               break;
 200
 201             case HEADER_END_OF_FILE:
 202               abort ();
 203             }
 204           break;
 205         }
 206
 207       previous_status = status;
 208     }
 209   while (logical_status == HEADER_STILL_UNREAD);
 210
 211   records_skipped = records_read - 1;
 212   new_record = xmalloc (record_size);
 213
 214   if (logical_status == HEADER_SUCCESS
 215       || logical_status == HEADER_SUCCESS_EXTENDED)
 216     {
 217       write_archive_to_stdout = 0;
 218
 219       /* Save away blocks before this one in this record.  */
 220
 221       new_blocks = current_block - record_start;
 222       if (new_blocks)
 223         memcpy (new_record, record_start, new_blocks * BLOCKSIZE);
 224
 225       if (logical_status == HEADER_SUCCESS)
 226         {
 227           /* FIXME: Pheew!  This is crufty code!  */
 228           logical_status = HEADER_STILL_UNREAD;
 229           goto flush_file;
 230         }
 231
 232       /* FIXME: Solaris 2.4 Sun cc (the ANSI one, not the old K&R) says:
 233          "delete.c", line 223: warning: loop not entered at top
 234          Reported by Bruno Haible.  */
 235       while (1)
 236         {
 237           enum read_header status;
 238
 239           /* Fill in a record.  */
 240
 241           if (current_block == record_end)
 242             flush_archive ();
 243           status = read_header (0);
 244
 245           if (status == HEADER_ZERO_BLOCK && ignore_zeros_option)
 246             {
 247               set_next_block_after (current_header);
 248               continue;
 249             }
 250           if (status == HEADER_END_OF_FILE || status == HEADER_ZERO_BLOCK)
 251             {
 252               logical_status = HEADER_END_OF_FILE;
 253               break;
 254             }
 255
 256           if (status == HEADER_FAILURE)
 257             {
 258               ERROR ((0, 0, _("Deleting non-header from archive")));
 259               set_next_block_after (current_header);
 260               continue;
 261             }
 262
 263           /* Found another header.  */
 264
 265           if (name = name_scan (current_file_name), name)
 266             {
 267               name->found = 1;
 268             flush_file:
 269               set_next_block_after (current_header);
 270               blocks_to_skip = (current_stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 271
 272               while (record_end - current_block <= blocks_to_skip)
 273                 {
 274                   blocks_to_skip -= (record_end - current_block);
 275                   flush_archive ();
 276                 }
 277               current_block += blocks_to_skip;
 278               blocks_to_skip = 0;
 279               continue;
 280             }
 281
 282           /* Copy header.  */
 283
 284           write_recent_blocks (recent_long_name, recent_long_name_blocks);
 285           write_recent_blocks (recent_long_link, recent_long_link_blocks);
 286           new_record[new_blocks] = *current_header;
 287           new_blocks++;
 288           blocks_to_keep
 289             = (current_stat.st_size + BLOCKSIZE - 1) / BLOCKSIZE;
 290           set_next_block_after (current_header);
 291           if (new_blocks == blocking_factor)
 292             write_record (1);
 293
 294           /* Copy data.  */
 295
 296           kept_blocks_in_record = record_end - current_block;
 297           if (kept_blocks_in_record > blocks_to_keep)
 298             kept_blocks_in_record = blocks_to_keep;
 299
 300           while (blocks_to_keep)
 301             {
 302               int count;
 303
 304               if (current_block == record_end)
 305                 {
 306                   flush_read ();
 307                   current_block = record_start;
 308                   kept_blocks_in_record = blocking_factor;
 309                   if (kept_blocks_in_record > blocks_to_keep)
 310                     kept_blocks_in_record = blocks_to_keep;
 311                 }
 312               count = kept_blocks_in_record;
 313               if (blocking_factor - new_blocks < count)
 314                 count = blocking_factor - new_blocks;
 315
 316               if (! count)
 317                 abort ();
 318
 319               memcpy (new_record + new_blocks, current_block, count * BLOCKSIZE);
 320               new_blocks += count;
 321               current_block += count;
 322               blocks_to_keep -= count;
 323               kept_blocks_in_record -= count;
 324
 325               if (new_blocks == blocking_factor)
 326                 write_record (1);
 327             }
 328         }
 329     }
 330
 331   if (logical_status == HEADER_END_OF_FILE)
 332     {
 333       /* Write the end of tape.  FIXME: we can't use write_eot here,
 334          as it gets confused when the input is at end of file.  */
 335
 336       int total_zero_blocks = 0;
 337
 338       do
 339         {
 340           int zero_blocks = blocking_factor - new_blocks;
 341           memset (new_record + new_blocks, 0, BLOCKSIZE * zero_blocks);
 342           total_zero_blocks += zero_blocks;
 343           write_record (total_zero_blocks < 2);
 344         }
 345       while (total_zero_blocks < 2);
 346     }
 347
 348   free (new_record);
 349
 350   if (! acting_as_filter && ! _isrmt (archive))
 351     {
 352 #if MSDOS
 353       int status = write (archive, "", 0);
 354 #else
 355       off_t pos = lseek (archive, (off_t) 0, SEEK_CUR);
 356       int status = pos < 0 ? -1 : ftruncate (archive, pos);
 357 #endif
 358       if (status != 0)
 359         truncate_warn (archive_name_array[0]);
 360     }
 361
 362   close_archive ();
 363   names_notfound ();
 364 }