lib/dpkg/db-fsys-load.c

   1 /*
   2  * libdpkg - Debian packaging suite library routines
   3  * db-fsys-load.c - (re)loading of database of files installed on system
   4  *
   5  * Copyright © 2008-2024 Guillem Jover <guillem@debian.org>
   6  * Copyright © 2022 Simon Richter <sjr@debian.org>
   7  *
   8  * This 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 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This 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 <https://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <config.h>
  23 #include <compat.h>
  24
  25 #include <sys/types.h>
  26 #include <sys/stat.h>
  27
  28 #include <errno.h>
  29
  30 #include <dpkg/dpkg.h>
  31 #include <dpkg/dpkg-db.h>
  32 #include <dpkg/db-fsys.h>
  33 #include <dpkg/i18n.h>
  34 #include <dpkg/debug.h>
  35
  36 enum dpkg_db_error
  37 dpkg_db_reopen(struct dpkg_db *db)
  38 {
  39         struct stat st_next;
  40         FILE *file_next;
  41
  42         if (db->pathname == NULL)
  43                 db->pathname = dpkg_db_get_path(db->name);
  44
  45         onerr_abort++;
  46
  47         file_next = fopen(db->pathname, "r");
  48         if (!file_next) {
  49                 if (errno != ENOENT)
  50                         ohshite(_("cannot open %s file"), db->pathname);
  51         } else {
  52                 setcloexec(fileno(file_next), db->pathname);
  53
  54                 if (fstat(fileno(file_next), &st_next))
  55                         ohshite(_("cannot get %s file metadata"), db->pathname);
  56
  57                 /*
  58                  * We need to keep the database file open so that the
  59                  * filesystem cannot reuse the inode number (f.ex. during
  60                  * multiple dpkg-divert invocations in a maintainer script),
  61                  * otherwise the following check might turn true, and we
  62                  * would skip reloading a modified database.
  63                  */
  64                 if (db->file &&
  65                     db->st.st_dev == st_next.st_dev &&
  66                     db->st.st_ino == st_next.st_ino) {
  67                         fclose(file_next);
  68                         onerr_abort--;
  69
  70                         debug(dbg_general, "%s: unchanged %s, skipping",
  71                               __func__, db->pathname);
  72                         return DPKG_DB_SAME;
  73                 }
  74                 db->st = st_next;
  75         }
  76         if (db->file)
  77                 fclose(db->file);
  78         db->file = file_next;
  79
  80         onerr_abort--;
  81
  82         if (db->file) {
  83                 debug(dbg_general, "%s: new %s, (re)loading",
  84                       __func__, db->pathname);
  85                 return DPKG_DB_LOAD;
  86         } else {
  87                 debug(dbg_general, "%s: missing %s, resetting",
  88                       __func__, db->pathname);
  89                 return DPKG_DB_NONE;
  90         }
  91 }