src/linux/dirs.c

   1 /*****************************************************************************
   2  * linux/dirs.c: Linux-specific directories
   3  *****************************************************************************
   4  * Copyright © 2008-2012 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <stdio.h>
  26 #include <string.h>
  27 #include <linux/limits.h>
  28
  29 #include <vlc_common.h>
  30 #include "libvlc.h"
  31 #include "config/configuration.h"
  32
  33 char *config_GetLibDir (void)
  34 {
  35     static struct
  36     {
  37         vlc_mutex_t lock;
  38         char path[PATH_MAX];
  39     } cache = {
  40         VLC_STATIC_MUTEX, "",
  41     };
  42
  43     /* Reading and parsing /proc/self/maps is slow, so cache the value since
  44      * it's guaranteed not to change during the life-time of the process. */
  45     vlc_mutex_lock(&cache.lock);
  46     if (cache.path[0] != '\0')
  47     {
  48         char *ret = strdup(cache.path);
  49         vlc_mutex_unlock(&cache.lock);
  50         return ret;
  51     }
  52     char *path = NULL;
  53
  54     /* Find the path to libvlc (i.e. ourselves) */
  55     FILE *maps = fopen ("/proc/self/maps", "rte");
  56     if (maps == NULL)
  57         goto error;
  58
  59     char *line = NULL;
  60     size_t linelen = 0;
  61     uintptr_t needle = (uintptr_t)config_GetLibDir;
  62
  63     for (;;)
  64     {
  65         ssize_t len = getline (&line, &linelen, maps);
  66         if (len == -1)
  67             break;
  68
  69         void *start, *end;
  70         if (sscanf (line, "%p-%p", &start, &end) < 2)
  71             continue;
  72         /* This mapping contains the address of this function. */
  73         if (needle < (uintptr_t)start || (uintptr_t)end <= needle)
  74             continue;
  75
  76         char *dir = strchr (line, '/');
  77         if (dir == NULL)
  78             continue;
  79
  80         char *file = strrchr (line, '/');
  81         if (end == NULL)
  82             continue;
  83         *file = '\0';
  84
  85         if (asprintf (&path, "%s/"PACKAGE, dir) == -1)
  86             path = NULL;
  87         break;
  88     }
  89
  90     free (line);
  91     fclose (maps);
  92 error:
  93     if (path == NULL)
  94         path = strdup(PKGLIBDIR);
  95     if (likely(path != NULL && sizeof(cache.path) > strlen(path)))
  96         strcpy(cache.path, path);
  97     vlc_mutex_unlock(&cache.lock);
  98     return path;
  99 }
 100
 101 char *config_GetDataDir (void)
 102 {
 103     const char *path = getenv ("VLC_DATA_PATH");
 104     if (path != NULL)
 105         return strdup (path);
 106
 107     char *libdir = config_GetLibDir ();
 108     if (libdir == NULL)
 109         return NULL; /* OOM */
 110
 111     char *datadir = NULL;
 112
 113     /* There are no clean ways to do this, are there?
 114      * Due to multilibs, we cannot simply append ../share/. */
 115     char *p = strstr (libdir, "/lib/");
 116     if (p != NULL)
 117     {
 118         char *p2;
 119         /* Deal with nested "lib" directories. Grmbl. */
 120         while ((p2 = strstr (p + 4, "/lib/")) != NULL)
 121             p = p2;
 122         *p = '\0';
 123
 124         if (unlikely(asprintf (&datadir, "%s/share/"PACKAGE, libdir) == -1))
 125             datadir = NULL;
 126     }
 127     free (libdir);
 128     return (datadir != NULL) ? datadir : strdup (PKGDATADIR);
 129 }