coretext: fix conversion from CFStringRef to utf8 buffer

The code incorrectly assumed that the utf8 characters could always be
represented with only one byte. This commit queries CFStringRef instances for
the actual amount of bytes needed.

diff --git a/libass/ass_coretext.c b/libass/ass_coretext.c
index ad054437f6d9e1e589bed0f5ea904bcbb681ced0..bf2e30140bc2e4ef58cc8cd870a07840ca52abc4 100644 (file)
--- a/libass/ass_coretext.c
+++ b/libass/ass_coretext.c
@@ -30,13 +30,15 @@
 
 static char *cfstr2buf(CFStringRef string)
 {
-    const char *buf_ptr = CFStringGetCStringPtr(string, kCFStringEncodingUTF8);
+    const int encoding = kCFStringEncodingUTF8;
+    const char *buf_ptr = CFStringGetCStringPtr(string, encoding);
     if (buf_ptr) {
         return strdup(buf_ptr);
     } else {
-        size_t buf_len = CFStringGetLength(string) + 1;
+        size_t len = CFStringGetLength(string);
+        CFIndex buf_len = CFStringGetMaximumSizeForEncoding(len, encoding);
         char *buf = malloc(buf_len);
-        CFStringGetCString(string, buf, buf_len, kCFStringEncodingUTF8);
+        CFStringGetCString(string, buf, buf_len, encoding);
         return buf;
     }
 }