[PATCH] spd_audio: Expose dlopened library's symbols to libs it loads.

[Christopher Brannon]

This fixes the following issue.
* Libao is loaded as an audio plugin.
* Libao loads its own plugins, using dlopen.
* Those plugins try to call functions defined in libao itself,
  but fail because the symbols aren't globally available.
---
 src/modules/spd_audio.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/modules/spd_audio.c b/src/modules/spd_audio.c
index 95b01f2..3b65bf7 100644
--- a/src/modules/spd_audio.c
+++ b/src/modules/spd_audio.c
@@ -53,6 +53,27 @@
 static int spd_audio_log_level;
 static lt_dlhandle lt_h;
 
+/* Dynamically load a library with RTLD_GLOBAL set.
+
+   This is needed when a dynamically-loaded library has its own plugins
+   that call into the parent library.
+   Most of the credit for this function goes to Gary Vaughan.
+*/
+static lt_dlhandle my_dlopenextglobal(const char *filename)
+{
+       lt_dlhandle handle = NULL;
+       lt_dladvise advise;
+
+       if (lt_dladvise_init(&advise))
+               return handle;
+
+       if (!lt_dladvise_ext(&advise) && !lt_dladvise_global(&advise))
+               handle = lt_dlopenadvise(filename, advise);
+
+       lt_dladvise_destroy(&advise);
+       return handle;
+}
+
 /* Open the audio device.
 
    Arguments:
@@ -91,7 +112,7 @@ AudioID *spd_audio_open(char *name, void **pars, char 
**error)
        }
 
        libname = g_strdup_printf(SPD_AUDIO_LIB_PREFIX "%s", name);
-       lt_h = lt_dlopenext(libname);
+       lt_h = my_dlopenextglobal(libname);
        g_free(libname);
        if (NULL == lt_h) {
                *error =
-- 
1.8.1.5