Fixed bug #1085 (Jump to NULL function pointer on ALSA_OpenDevice)

 Bruno      2010-12-16 02:41:51 PST

Fix segfault in ALSA_OpenDevice()

When alsa is linked to libsdl instead of being loaded on demand at runtime the
alsa macro snd_pcm_hw_params_alloca(ptr); misbehaves.

That macro calls snd_pcm_hw_params_sizeof() in order to determine the amount of
memory to allocate but due to mis-placed define that function is replaced with
ALSA_snd_pcm_hw_params_sizeof by preprocessor (and in case of link to alsa that
function pointer is initialized to itself).

Attached patch fixes the issue.

src/audio/alsa/SDL_alsa_audio.c

@@ -85,11 +85,11 @@ static int (*ALSA_snd_pcm_sw_params_set_start_threshold)
 static int (*ALSA_snd_pcm_sw_params) (snd_pcm_t *, snd_pcm_sw_params_t *);
 static int (*ALSA_snd_pcm_nonblock) (snd_pcm_t *, int);
 static int (*ALSA_snd_pcm_wait)(snd_pcm_t *, int);
-#define snd_pcm_hw_params_sizeof ALSA_snd_pcm_hw_params_sizeof
-#define snd_pcm_sw_params_sizeof ALSA_snd_pcm_sw_params_sizeof
 
 
 #ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC
+#define snd_pcm_hw_params_sizeof ALSA_snd_pcm_hw_params_sizeof
+#define snd_pcm_sw_params_sizeof ALSA_snd_pcm_sw_params_sizeof
 
 static const char *alsa_library = SDL_AUDIO_DRIVER_ALSA_DYNAMIC;
 static void *alsa_handle = NULL;