Fixed bug 4820 - SDL assumes RW_SEEK_SET == SEEK_SET

src/file/SDL_rwops.c

@@ -361,13 +361,29 @@ stdio_size(SDL_RWops * context)
 static Sint64 SDLCALL
 stdio_seek(SDL_RWops * context, Sint64 offset, int whence)
 {
+    int stdiowhence;
+
+    switch (whence) {
+    case RW_SEEK_SET:
+        stdiowhence = SEEK_SET;
+        break;
+    case RW_SEEK_CUR:
+        stdiowhence = SEEK_CUR;
+        break;
+    case RW_SEEK_END:
+        stdiowhence = SEEK_END;
+        break;
+    default:
+        return SDL_SetError("Unknown value for 'whence'");
+    }
+
 #if defined(FSEEK_OFF_MIN) && defined(FSEEK_OFF_MAX)
     if (offset < (Sint64)(FSEEK_OFF_MIN) || offset > (Sint64)(FSEEK_OFF_MAX)) {
         return SDL_SetError("Seek offset out of range");
     }
 #endif
 
-    if (fseek(context->hidden.stdio.fp, (fseek_off_t)offset, whence) == 0) {
+    if (fseek(context->hidden.stdio.fp, (fseek_off_t)offset, stdiowhence) == 0) {
         Sint64 pos = ftell(context->hidden.stdio.fp);
         if (pos < 0) {
             return SDL_SetError("Couldn't get stream offset");