Added SDL_GetErrorMsg() to get the error message in a thread-safe way

include/SDL_error.h

@@ -37,9 +37,45 @@ extern "C" {
 #endif
 
 /* Public functions */
-/* SDL_SetError() unconditionally returns -1. */
+
+
+/**
+ *  \brief Set the error message for the current thread
+ *
+ *  \return -1, there is no error handling for this function
+ */
 extern DECLSPEC int SDLCALL SDL_SetError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) SDL_PRINTF_VARARG_FUNC(1);
+
+/**
+ *  \brief Get the last error message that was set
+ *
+ * SDL API functions may set error messages and then succeed, so you should
+ * only use the error value if a function fails.
+ * 
+ * This returns a pointer to a static buffer for convenience and should not
+ * be called by multiple threads simultaneously.
+ *
+ *  \return a pointer to the last error message that was set
+ */
 extern DECLSPEC const char *SDLCALL SDL_GetError(void);
+
+/**
+ *  \brief Get the last error message that was set for the current thread
+ *
+ * SDL API functions may set error messages and then succeed, so you should
+ * only use the error value if a function fails.
+ * 
+ *  \param errstr A buffer to fill with the last error message that was set
+ *                for the current thread
+ *  \param maxlen The size of the buffer pointed to by the errstr parameter
+ *
+ *  \return errstr
+ */
+extern DECLSPEC char * SDLCALL SDL_GetErrorMsg(char *errstr, int maxlen);
+
+/**
+ *  \brief Clear the error message for the current thread
+ */
 extern DECLSPEC void SDLCALL SDL_ClearError(void);
 
 /**

src/SDL_error.c

@@ -39,8 +39,6 @@ SDL_LookupString(const char *key)
 
 /* Public functions */
 
-static char *SDL_GetErrorMsg(char *errstr, int maxlen);
-
 int
 SDL_SetError(SDL_PRINTF_FORMAT_STRING const char *fmt, ...)
 {
@@ -192,7 +190,7 @@ main(int argc, char *argv[])
 /* This function has a bit more overhead than most error functions
    so that it supports internationalization and thread-safe errors.
 */
-static char *
+char *
 SDL_GetErrorMsg(char *errstr, int maxlen)
 {
     SDL_error *error;

src/dynapi/SDL_dynapi_overrides.h

@@ -756,3 +756,4 @@
 #define SDL_JoystickSetVirtualBall SDL_JoystickSetVirtualBall_REAL
 #define SDL_JoystickSetVirtualButton SDL_JoystickSetVirtualButton_REAL
 #define SDL_JoystickSetVirtualHat SDL_JoystickSetVirtualHat_REAL
+#define SDL_GetErrorMsg SDL_GetErrorMsg_REAL

src/dynapi/SDL_dynapi_procs.h

@@ -816,3 +816,4 @@ SDL_DYNAPI_PROC(int,SDL_JoystickSetVirtualAxis,(SDL_Joystick *a, int b, Sint16 c
 SDL_DYNAPI_PROC(int,SDL_JoystickSetVirtualBall,(SDL_Joystick *a, int b, Sint16 c, Sint16 d),(a,b,c,d),return)
 SDL_DYNAPI_PROC(int,SDL_JoystickSetVirtualButton,(SDL_Joystick *a, int b, Uint8 c),(a,b,c),return)
 SDL_DYNAPI_PROC(int,SDL_JoystickSetVirtualHat,(SDL_Joystick *a, int b, Uint8 c),(a,b,c),return)
+SDL_DYNAPI_PROC(char*,SDL_GetErrorMsg,(char *a, int b),(a,b),return)