access/alsa.c: fixup 4b0e0dcd

Previous commit was wrong, this fixes it.

modules/access/alsa.c

@@ -363,7 +363,7 @@ static int Demux( demux_t *p_demux )
 static block_t* GrabAudio( demux_t *p_demux )
 {
     demux_sys_t *p_sys = p_demux->p_sys;
-    int i_read, i_correct, i_error;
+    int i_read, i_correct;
     block_t *p_block;
 
     if( p_sys->p_block ) p_block = p_sys->p_block;
@@ -379,13 +379,15 @@ static block_t* GrabAudio( demux_t *p_demux )
 
     /* ALSA */
     i_read = snd_pcm_readi( p_sys->p_alsa_pcm, p_block->p_buffer, p_sys->i_alsa_chunk_size );
-    if( i_read == -EAGAIN || ((i_read >= 0) && (i_read < p_sys->i_alsa_chunk_size)) )
-        i_error = snd_pcm_wait( p_sys->p_alsa_pcm, 10 ); /* See poll() comment in oss.c */
-    else i_error = i_read;
+    if( i_read == -EAGAIN )
+    {
+        snd_pcm_wait( p_sys->p_alsa_pcm, 10 ); /* See poll() comment in oss.c */
+        return NULL;
+    }
 
-    if( i_error <= 0 )
+    if( i_read <= 0 )
     {
-        switch( i_error )
+        switch( i_read )
         {
             case -EPIPE:
                 /* xrun */