src/update.c

   1 /* Update a tar archive.
   2
   3    Copyright 1988-2023 Free Software Foundation, Inc.
   4
   5    This file is part of GNU tar.
   6
   7    GNU tar is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    GNU tar is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 /* Implement the 'r', 'u' and 'A' options for tar.  'A' means that the
  21    file names are tar files, and they should simply be appended to the end
  22    of the archive.  No attempt is made to record the reads from the args; if
  23    they're on raw tape or something like that, it'll probably lose...  */
  24
  25 #include <system.h>
  26 #include <quotearg.h>
  27 #include "common.h"
  28
  29 /* FIXME: This module should not directly handle the following variable,
  30    instead, this should be done in buffer.c only.  */
  31 extern union block *current_block;
  32
  33 /* We've hit the end of the old stuff, and its time to start writing new
  34    stuff to the tape.  This involves seeking back one record and
  35    re-writing the current record (which has been changed).
  36    FIXME: Either eliminate it or move it to common.h.
  37 */
  38 bool time_to_start_writing;
  39
  40 /* Pointer to where we started to write in the first record we write out.
  41    This is used if we can't backspace the output and have to null out the
  42    first part of the record.  */
  43 char *output_start;
  44
  45 static bool acting_as_filter;
  46
  47 /* Catenate file FILE_NAME to the archive without creating a header for it.
  48    It had better be a tar file or the archive is screwed.  */
  49 static void
  50 append_file (char *file_name)
  51 {
  52   int handle = openat (chdir_fd, file_name, O_RDONLY | O_BINARY);
  53
  54   if (handle < 0)
  55     {
  56       open_error (file_name);
  57       return;
  58     }
  59
  60   while (true)
  61     {
  62       union block *start = find_next_block ();
  63       size_t status = safe_read (handle, start->buffer,
  64                                  available_space_after (start));
  65       if (status == 0)
  66         break;
  67       if (status == SAFE_READ_ERROR)
  68         read_fatal (file_name);
  69       if (status % BLOCKSIZE)
  70         memset (start->buffer + status - status % BLOCKSIZE, 0,
  71                 BLOCKSIZE - status % BLOCKSIZE);
  72       set_next_block_after (start + (status - 1) / BLOCKSIZE);
  73     }
  74
  75   if (close (handle) != 0)
  76     close_error (file_name);
  77 }
  78
  79 /* Implement the 'r' (add files to end of archive), and 'u' (add files
  80    to end of archive if they aren't there, or are more up to date than
  81    the version in the archive) commands.  */
  82 void
  83 update_archive (void)
  84 {
  85   enum read_header previous_status = HEADER_STILL_UNREAD;
  86   bool found_end = false;
  87
  88   name_gather ();
  89   open_archive (ACCESS_UPDATE);
  90   acting_as_filter = strcmp (archive_name_array[0], "-") == 0;
  91   xheader_forbid_global ();
  92
  93   while (!found_end)
  94     {
  95       enum read_header status = read_header (&current_header,
  96                                              &current_stat_info,
  97                                              read_header_auto);
  98
  99       switch (status)
 100         {
 101         case HEADER_STILL_UNREAD:
 102         case HEADER_SUCCESS_EXTENDED:
 103           abort ();
 104
 105         case HEADER_SUCCESS:
 106           {
 107             struct name *name;
 108
 109             decode_header (current_header, &current_stat_info,
 110                            &current_format, 0);
 111             transform_stat_info (current_header->header.typeflag,
 112                                  &current_stat_info);
 113             archive_format = current_format;
 114
 115             if (subcommand_option == UPDATE_SUBCOMMAND
 116                 && (name = name_scan (current_stat_info.file_name)) != NULL)
 117               {
 118                 struct stat s;
 119
 120                 chdir_do (name->change_dir);
 121                 if (deref_stat (current_stat_info.file_name, &s) == 0)
 122                   {
 123                     if (S_ISDIR (s.st_mode))
 124                       {
 125                         char *p, *dirp = tar_savedir (name->name, 1);
 126                         if (dirp)
 127                           {
 128                             namebuf_t nbuf = namebuf_create (name->name);
 129
 130                             for (p = dirp; *p; p += strlen (p) + 1)
 131                               addname (namebuf_name (nbuf, p),
 132                                        name->change_dir, false, NULL);
 133
 134                             namebuf_free (nbuf);
 135                             free (dirp);
 136
 137                             remname (name);
 138                           }
 139                       }
 140                     else if (tar_timespec_cmp (get_stat_mtime (&s),
 141                                                current_stat_info.mtime)
 142                              <= 0)
 143                       remname (name);
 144                   }
 145               }
 146
 147             skim_member (acting_as_filter);
 148             break;
 149           }
 150
 151         case HEADER_ZERO_BLOCK:
 152           current_block = current_header;
 153           found_end = true;
 154           break;
 155
 156         case HEADER_END_OF_FILE:
 157           found_end = true;
 158           break;
 159
 160         case HEADER_FAILURE:
 161           set_next_block_after (current_header);
 162           switch (previous_status)
 163             {
 164             case HEADER_STILL_UNREAD:
 165               WARN ((0, 0, _("This does not look like a tar archive")));
 166               FALLTHROUGH;
 167             case HEADER_SUCCESS:
 168             case HEADER_ZERO_BLOCK:
 169               ERROR ((0, 0, _("Skipping to next header")));
 170               FALLTHROUGH;
 171             case HEADER_FAILURE:
 172               break;
 173
 174             case HEADER_END_OF_FILE:
 175             case HEADER_SUCCESS_EXTENDED:
 176               abort ();
 177             }
 178           break;
 179         }
 180
 181       tar_stat_destroy (&current_stat_info);
 182       previous_status = status;
 183     }
 184
 185   reset_eof ();
 186   time_to_start_writing = true;
 187   output_start = current_block->buffer;
 188
 189   {
 190     struct name const *p;
 191     while ((p = name_from_list ()) != NULL)
 192       {
 193         char *file_name = p->name;
 194         if (excluded_name (file_name, NULL))
 195           continue;
 196         if (interactive_option && !confirm ("add", file_name))
 197           continue;
 198         if (subcommand_option == CAT_SUBCOMMAND)
 199           append_file (file_name);
 200         else
 201           dump_file (0, file_name, file_name);
 202       }
 203   }
 204
 205   write_eot ();
 206   close_archive ();
 207   finish_deferred_unlinks ();
 208   names_notfound ();
 209 }