ucrtbase: Handle the _s variant of vsscanf.

dlls/msvcrt/msvcrt.h

@@ -1139,4 +1139,6 @@ extern char* __cdecl __unDName(char *,const char*,int,malloc_func_t,free_func_t,
 #define UCRTBASE_SCANF_LEGACY_WIDE_SPECIFIERS            (0x0002)
 #define UCRTBASE_SCANF_LEGACY_MSVCRT_COMPATIBILITY       (0x0004)
 
+#define UCRTBASE_SCANF_MASK                              (0x0007)
+
 #endif /* __WINE_MSVCRT_H */

dlls/msvcrt/scanf.c

@@ -671,9 +671,15 @@ int CDECL MSVCRT__stdio_common_vsscanf(unsigned __int64 options,
                                        MSVCRT__locale_t locale,
                                        __ms_va_list valist)
 {
-    if (options != UCRTBASE_SCANF_LEGACY_WIDE_SPECIFIERS)
+    /* LEGACY_WIDE_SPECIFIERS only has got an effect on the wide
+     * scanf. LEGACY_MSVCRT_COMPATIBILITY affects parsing of nan/inf,
+     * but parsing of those isn't implemented at all yet. */
+    if (options & ~UCRTBASE_SCANF_MASK)
         FIXME("options %s not handled\n", wine_dbgstr_longlong(options));
-    return MSVCRT_vsnscanf_l(input, length, format, locale, valist);
+    if (options & UCRTBASE_SCANF_SECURECRT)
+        return MSVCRT_vsnscanf_s_l(input, length, format, locale, valist);
+    else
+        return MSVCRT_vsnscanf_l(input, length, format, locale, valist);
 }
 
 /*********************************************************************