SDL: alsa: Fix possible uninitialized string

SDL Commits
1 
From c8061ed2d1ca42b703deaca22003bbdeb18f09ed Mon Sep 17 00:00:00 2001
From: Cameron Gutman <[EMAIL REDACTED]>
Date: Sat, 13 Nov 2021 10:33:37 -0600
Subject: [PATCH] alsa: Fix possible uninitialized string

---
 src/audio/alsa/SDL_alsa_audio.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/audio/alsa/SDL_alsa_audio.c b/src/audio/alsa/SDL_alsa_audio.c
index d6f2a1050d..79c879fb63 100644
--- a/src/audio/alsa/SDL_alsa_audio.c
+++ b/src/audio/alsa/SDL_alsa_audio.c
@@ -656,10 +656,11 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
 #ifdef SND_CHMAP_API_VERSION
     chmap = ALSA_snd_pcm_get_chmap(pcm_handle);
     if (chmap) {
-        ALSA_snd_pcm_chmap_print(chmap, sizeof(chmap_str), chmap_str);
-        if (SDL_strcmp("FL FR FC LFE RL RR", chmap_str) == 0 ||
-            SDL_strcmp("FL FR FC LFE SL SR", chmap_str) == 0) {
-            this->hidden->swizzle_func = no_swizzle;
+        if (ALSA_snd_pcm_chmap_print(chmap, sizeof(chmap_str), chmap_str) > 0) {
+            if (SDL_strcmp("FL FR FC LFE RL RR", chmap_str) == 0 ||
+                SDL_strcmp("FL FR FC LFE SL SR", chmap_str) == 0) {
+                this->hidden->swizzle_func = no_swizzle;
+            }
         }
         free(chmap);
     }