Fixed bug 3696 - SDL_ShowMessageBox displays different error from intended
Mark Callow
SDL_ShowMessageBox calls SDL_CaptureMouse which, in the UIKit driver, raises a “That operation is not supported” error, overwriting the SDL error that an application may be trying to report.
This is because UIKit SDL_CaptureMouse returns SDL_Unsupported() which ends up calling SDL_SetError() which has the following code:
/* If we are in debug mode, print out an error message */
SDL_LogDebug(SDL_LOG_CATEGORY_ERROR, "%s", SDL_GetError());
The SDL_GetError call here overwrites the static buffer…..
Although an application can avoid this by using SDL_GetErrorMsg(char* errstr, int maxlen) to avoid the static buffer, SDL should be fixed.
The fix is simple. In SDL_SetError change
SDL_LogDebug(SDL_LOG_CATEGORY_ERROR, "%s", SDL_GetError());
to
SDL_LogDebug(SDL_LOG_CATEGORY_ERROR, "%s", error);
where error is the pointer to the buffer where it assembled the message.
diff --git a/src/SDL_error.c b/src/SDL_error.c
index 8af9cdd..498679a 100644
--- a/src/SDL_error.c
+++ b/src/SDL_error.c
@@ -49,6 +49,8 @@
/* Public functions */
+static char *SDL_GetErrorMsg(char *errstr, int maxlen);
+
int
SDL_SetError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...)
{
@@ -110,14 +112,19 @@
}
va_end(ap);
- /* If we are in debug mode, print out an error message */
- SDL_LogDebug(SDL_LOG_CATEGORY_ERROR, "%s", SDL_GetError());
-
+ if (SDL_LogGetPriority(SDL_LOG_CATEGORY_ERROR) <= SDL_LOG_PRIORITY_DEBUG) {
+ /* If we are in debug mode, print out an error message
+ * Avoid stomping on the static buffer in GetError, just
+ * in case this is called while processing a ShowMessageBox to
+ * show an error already in that static buffer.
+ */
+ char errmsg[SDL_ERRBUFIZE];
+ SDL_GetErrorMsg(errmsg, sizeof(errmsg));
+ SDL_LogDebug(SDL_LOG_CATEGORY_ERROR, "%s", errmsg);
+ }
return -1;
}
-static char *SDL_GetErrorMsg(char *errstr, int maxlen);
-
/* Available for backwards compatibility */
const char *
SDL_GetError(void)
