playmus no longer recognising WAV files since the SDL_RWops API change

[Simon McVittie]

After upgrading from a few days ago's SDL3 and SDL_mixer to libsdl-org/SDL@a2d5942 and mixer 139b748, I can still play a simple stereo WAV file with playwave:

$ .../playwave /usr/share/sounds/alsa/Front_Center.wav
INFO: Opened audio at 48000 Hz 32 bit stereo

but the same with playmus no longer works:

$ .../playmus /usr/share/sounds/alsa/Front_Center.wav
INFO: Opened audio at 48000 Hz 32 bit stereo audio buffer
INFO: Couldn't load /usr/share/sounds/alsa/Front_Center.wav: Unrecognized audio format

[Ozkan Sezer]

It fails during chunk_type and chunk_length read in LoadWAVMusic():
https://github.com/libsdl-org/SDL_mixer/blob/main/src/codecs/music_wav.c#L1655-L1658

It is supposed to break out of the for loop if it hits chunk_length == 0:
https://github.com/libsdl-org/SDL_mixer/blob/main/src/codecs/music_wav.c#L1655-L1658

It was possible before because with the old SDL_ReadLE32 we didn't care
about read success: I guess we shouldn't now either, or change the logic.

EDIT: Possible similar issues elsewhere in music_wav.c (possibly in other
places too???)

CC: @slouken

[Ozkan Sezer]

For what it's worth, patching like the following cures the reported issue with WAVE files:

diff --git a/src/codecs/music_wav.c b/src/codecs/music_wav.c
index e04d7fe..7cf277a 100644
--- a/src/codecs/music_wav.c
+++ b/src/codecs/music_wav.c
@@ -1652,10 +1652,8 @@ static SDL_bool LoadWAVMusic(WAV_Music *wave)
 
     /* Read the chunks */
     for (; ;) {
-        if (!SDL_ReadU32LE(src, &chunk_type) ||
-            !SDL_ReadU32LE(src, &chunk_length)) {
-            return SDL_FALSE;
-        }
+        SDL_ReadU32LE(src, &chunk_type);  /* not checking success for these two. */
+        SDL_ReadU32LE(src, &chunk_length);
 
         if (chunk_length == 0)
             break;

[Sam Lantinga]

How about this?

diff --git a/src/codecs/music_wav.c b/src/codecs/music_wav.c
index e04d7fe2..1889bb32 100644
--- a/src/codecs/music_wav.c
+++ b/src/codecs/music_wav.c
@@ -1654,6 +1654,9 @@ static SDL_bool LoadWAVMusic(WAV_Music *wave)
     for (; ;) {
         if (!SDL_ReadU32LE(src, &chunk_type) ||
             !SDL_ReadU32LE(src, &chunk_length)) {
+            if (src->status == SDL_RWOPS_STATUS_EOF) {
+                break;
+            }
             return SDL_FALSE;
         }

[Ozkan Sezer]

Tested to work.

I wonder whether there are any other such places that need this kind of care (and not just in SDL_mixer but SDL_image and SDL_ttf too.)

[Sam Lantinga]

Possibly. If people continue to ignore the return value it'll work the way it always had. It's not great practice, but it was the only option in the previous API. I think this is an improvement, we just have to keep an eye out for this kind of thing.

[Sam Lantinga]

Fixed in 14f1eb2