dlsym: add support for ALSA_PLUGIN_DIR environment variable

In some cases, it may be useful to specify the plugin directory
using the environment variable.

BugLink: https://github.com/alsa-project/alsa-lib/issues/82
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/src/dlmisc.c b/src/dlmisc.c
index 1a60e0dda30b2a6f6b953e443f477f4900a14529..8a600dec13428274802ee80a6bdd1b06dd021081 100644 (file)
--- a/src/dlmisc.c
+++ b/src/dlmisc.c
@@ -43,8 +43,8 @@
 struct snd_dlsym_link *snd_dlsym_start = NULL;
 #endif
 #ifdef DL_ORIGIN_AVAILABLE
-static int snd_libdir_plugin_dir_set = 0;
-static char *snd_libdir_origin = NULL;
+static int snd_plugin_dir_set = 0;
+static char *snd_plugin_dir = NULL;
 #endif
 #endif
 
@@ -65,6 +65,22 @@ static inline void snd_dlpath_lock(void) {}
 static inline void snd_dlpath_unlock(void) {}
 #endif
 
+static void snd_dlinfo_origin(char *path, size_t path_len)
+{
+#ifdef DL_ORIGIN_AVAILABLE
+       struct link_map *links;
+       Dl_info info;
+       char origin[PATH_MAX];
+       if (dladdr1(&snd_dlpath, &info, (void**)&links, RTLD_DL_LINKMAP) == 0)
+               return;
+       if (dlinfo(links, RTLD_DI_ORIGIN, origin))
+               return;
+       snprintf(path, path_len, "%s/alsa-lib", origin);
+       if (access(path, X_OK) == 0)
+               snd_plugin_dir = strdup(path);
+#endif
+}
+
 /**
  *
  * \brief Compose the dynamic path
@@ -75,30 +91,19 @@ static inline void snd_dlpath_unlock(void) {}
  */
 int snd_dlpath(char *path, size_t path_len, const char *name)
 {
-#ifdef DL_ORIGIN_AVAILABLE
        snd_dlpath_lock();
-       if (!snd_libdir_plugin_dir_set) {
-               struct link_map *links;
-               Dl_info info;
-               char origin[PATH_MAX];
-               if (dladdr1(&snd_dlpath, &info, (void**)&links, RTLD_DL_LINKMAP) == 0)
-                       links = NULL;
-               if (links != NULL && dlinfo(links, RTLD_DI_ORIGIN, origin) == 0) {
-                       snprintf(path, path_len, "%s/alsa-lib", origin);
-                       if (access(path, X_OK) == 0)
-                               snd_libdir_origin = strdup(origin);
+       if (!snd_plugin_dir_set) {
+               const char *env = getenv("ALSA_PLUGIN_DIR");
+               if (env) {
+                       snd_plugin_dir = strdup(env);
+               } else {
+                       snd_dlinfo_origin(path, path_len);
                }
-               snd_libdir_plugin_dir_set = 1;
-       }
-       if (snd_libdir_origin) {
-               snprintf(path, path_len, "%s/alsa-lib/%s", snd_libdir_origin, name);
-       } else {
-               snprintf(path, path_len, "%s/%s", ALSA_PLUGIN_DIR, name);
+               snd_plugin_dir_set = 1;
        }
+       snprintf(path, path_len, "%s/%s",
+                snd_plugin_dir ? snd_plugin_dir : ALSA_PLUGIN_DIR, name);
        snd_dlpath_unlock();
-#else
-       snprintf(path, path_len, "%s/%s", ALSA_PLUGIN_DIR, name);
-#endif
        return 0;
 }
 
@@ -450,9 +455,9 @@ void snd_dlobj_cache_cleanup(void)
        snd_dlobj_unlock();
 #ifdef DL_ORIGIN_AVAILABLE
        snd_dlpath_lock();
-       snd_libdir_plugin_dir_set = 0;
-       free(snd_libdir_origin);
-       snd_libdir_origin = NULL;
+       snd_plugin_dir_set = 0;
+       free(snd_plugin_dir);
+       snd_plugin_dir = NULL;
        snd_dlpath_unlock();
 #endif
 }