Update TTF_GetScript description and nul-termate the script arg

SDL_ttf.c

@@ -3128,29 +3128,23 @@ int TTF_SetFontScriptName(TTF_Font *font, const char *script)
 #endif
 }
 
-extern DECLSPEC int SDLCALL TTF_GetScript(Uint32 ch, char* script)
+extern DECLSPEC int SDLCALL TTF_GetScript(Uint32 ch, char script[5])
 {
 #if TTF_USE_HARFBUZZ
 
+    TTF_CHECK_POINTER(script, -1);
+
     hb_buffer_t* hb_buffer = hb_buffer_create();
 
-    if (hb_buffer == NULL)
-    {
+    if (hb_buffer == NULL) {
         TTF_SetError("Cannot create harfbuzz buffer");
         return -1;
     }
 
-    if (script == NULL || SDL_strlen(script) != 4)
-    {
-        return -1;
-    }
-
     hb_unicode_funcs_t* hb_unicode_functions = hb_buffer_get_unicode_funcs(hb_buffer);
 
-    if (hb_unicode_functions == NULL)
-    {
+    if (hb_unicode_functions == NULL) {
         TTF_SetError("Cannot get harfbuzz unicode funcs");
-
         hb_buffer_destroy(hb_buffer);
         return -1;
     }
@@ -3164,6 +3158,7 @@ extern DECLSPEC int SDLCALL TTF_GetScript(Uint32 ch, char* script)
     script[1] = (char)untagged_script[1];
     script[2] = (char)untagged_script[2];
     script[3] = (char)untagged_script[3];
+    script[4] = '\0';
 
     hb_buffer_destroy(hb_buffer);
     return 0;

SDL_ttf.h

@@ -2312,19 +2312,21 @@ extern DECLSPEC int SDLCALL TTF_SetFontDirection(TTF_Font *font, TTF_Direction d
 extern DECLSPEC int SDLCALL TTF_SetFontScriptName(TTF_Font *font, const char *script);
 
 /**
- * Retrieves the script to which unicode character belongs.
+ * Query the script to which unicode character belongs.
  *
- * The supplied script value must be exactly four characters.
+ * The supplied script pointer should be able to hold four characters and
+ * the null-terminator.
  *
  * If SDL_ttf was not built with HarfBuzz support, this function returns -1.
  *
- * \param ch the character code to check.
- * \param script the script output string.
+ * \param ch the character to check.
+ * \param script on return, filled in with the the script as a null-terminated
+ *               string of exactly 4 characters
  * \returns 0 on success, or -1 on error.
  *
  * \since This function is available since SDL_ttf ?.
  */
-extern DECLSPEC int SDLCALL TTF_GetScript(Uint32 ch, char* script);
+extern DECLSPEC int SDLCALL TTF_GetScript(Uint32 ch, char script[5]);
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus