ao_coreaudio: fix potential UB in error cases

mNumberChannelDescriptions being 0 is pretty much an error, but if it
can happen, then the code checking the chmap below will trigger UB, as
chmap is not initialized at all.

Also, simplify the code a little: we never change the number of
channels, so this is just fine.

1 files changed, 2 insertions, 3 deletions

diff --git a/audio/out/ao_coreaudio_chmap.c b/audio/out/ao_coreaudio_chmap.c
index 52ea81d5c7..df6b188656 100644
--- a/audio/out/ao_coreaudio_chmap.c
+++ b/audio/out/ao_coreaudio_chmap.c
@@ -151,6 +151,7 @@ static bool ca_layout_to_mp_chmap(struct ao *ao, AudioChannelLayout *layout,
         return false;
     }
 
+    chmap->num = l->mNumberChannelDescriptions;
     for (int n = 0; n < l->mNumberChannelDescriptions; n++) {
         AudioChannelLabel label = l->mChannelDescriptions[n].mChannelLabel;
         int speaker = ca_label_to_mp_speaker_id(label);
@@ -158,10 +159,8 @@ static bool ca_layout_to_mp_chmap(struct ao *ao, AudioChannelLayout *layout,
             MP_VERBOSE(ao, "channel label=%u unusable to build channel "
                            "bitmap, skipping layout\n", (unsigned) label);
             goto coreaudio_error;
-        } else {
-            chmap->speaker[n] = speaker;
-            chmap->num = n + 1;
         }
+        chmap->speaker[n] = speaker;
     }
 
     talloc_free(talloc_ctx);