lib/dpkg/db-fsys-divert.c

   1 /*
   2  * libdpkg - Debian packaging suite library routines
   3  * db-fsys-divert.c - management of filesystem diverted files database
   4  *
   5  * Copyright © 1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
   6  * Copyright © 2000, 2001 Wichert Akkerman <wakkerma@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 #include <string.h>
  30 #include <pwd.h>
  31 #include <grp.h>
  32 #include <fcntl.h>
  33 #include <unistd.h>
  34 #include <stdlib.h>
  35
  36 #include <dpkg/i18n.h>
  37 #include <dpkg/dpkg.h>
  38 #include <dpkg/dpkg-db.h>
  39 #include <dpkg/debug.h>
  40 #include <dpkg/db-fsys.h>
  41
  42 static struct fsys_diversion *diversions = NULL;
  43 static char *diversionsname;
  44
  45 void
  46 ensure_diversions(void)
  47 {
  48         static struct stat sb_prev;
  49         struct stat sb_next;
  50         char linebuf[MAXDIVERTFILENAME];
  51         static FILE *file_prev;
  52         FILE *file;
  53         struct fsys_diversion *ov, *oicontest, *oialtname;
  54
  55         if (diversionsname == NULL)
  56                 diversionsname = dpkg_db_get_path(DIVERSIONSFILE);
  57
  58         onerr_abort++;
  59
  60         file = fopen(diversionsname, "r");
  61         if (!file) {
  62                 if (errno != ENOENT)
  63                         ohshite(_("failed to open diversions file"));
  64         } else {
  65                 setcloexec(fileno(file), diversionsname);
  66
  67                 if (fstat(fileno(file), &sb_next))
  68                         ohshite(_("failed to fstat diversions file"));
  69
  70                 /*
  71                  * We need to keep the database file open so that the
  72                  * filesystem cannot reuse the inode number (f.ex. during
  73                  * multiple dpkg-divert invocations in a maintainer script),
  74                  * otherwise the following check might turn true, and we
  75                  * would skip reloading a modified database.
  76                  */
  77                 if (file_prev &&
  78                     sb_prev.st_dev == sb_next.st_dev &&
  79                     sb_prev.st_ino == sb_next.st_ino) {
  80                         fclose(file);
  81                         onerr_abort--;
  82                         debug(dbg_general, "%s: same, skipping", __func__);
  83                         return;
  84                 }
  85                 sb_prev = sb_next;
  86         }
  87         if (file_prev)
  88                 fclose(file_prev);
  89         file_prev = file;
  90
  91         for (ov = diversions; ov; ov = ov->next) {
  92                 ov->useinstead->divert->camefrom->divert = NULL;
  93                 ov->useinstead->divert = NULL;
  94         }
  95         diversions = NULL;
  96         if (!file) {
  97                 onerr_abort--;
  98                 debug(dbg_general, "%s: none, resetting", __func__);
  99                 return;
 100         }
 101         debug(dbg_general, "%s: new, (re)loading", __func__);
 102
 103         while (fgets_checked(linebuf, sizeof(linebuf), file, diversionsname) >= 0) {
 104                 oicontest = nfmalloc(sizeof(*oicontest));
 105                 oialtname = nfmalloc(sizeof(*oialtname));
 106
 107                 oialtname->camefrom = fsys_hash_find_node(linebuf, 0);
 108                 oialtname->useinstead = NULL;
 109
 110                 fgets_must(linebuf, sizeof(linebuf), file, diversionsname);
 111                 oicontest->useinstead = fsys_hash_find_node(linebuf, 0);
 112                 oicontest->camefrom = NULL;
 113
 114                 fgets_must(linebuf, sizeof(linebuf), file, diversionsname);
 115                 oicontest->pkgset = strcmp(linebuf, ":") ?
 116                                     pkg_hash_find_set(linebuf) : NULL;
 117                 oialtname->pkgset = oicontest->pkgset;
 118
 119                 if (oialtname->camefrom->divert ||
 120                     oicontest->useinstead->divert)
 121                         ohshit(_("conflicting diversions involving '%.250s' or '%.250s'"),
 122                                oialtname->camefrom->name, oicontest->useinstead->name);
 123
 124                 oialtname->camefrom->divert = oicontest;
 125                 oicontest->useinstead->divert = oialtname;
 126
 127                 oicontest->next = diversions;
 128                 diversions = oicontest;
 129         }
 130
 131         onerr_abort--;
 132 }