ucrtbase: Always return the full string length in __stdio_common_vs[w]printf for a NULL buffer.

If the target is a NULL buffer (with a zero length), we should always return the full size the format would have needed, even if UCRTBASE_PRINTF_STANDARD_SNPRINTF_BEHAVIOUR isn't specified. Signed-off-by: Martin Storsjo <martin@martin.st> Signed-off-by: Piotr Caban <piotr@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

ucrtbase: Always return the full string length in __stdio_common_vs[w]printf for a NULL buffer.
ee32799d · Martin Storsjo · Alexandre Julliard · 29a0537d · ee32799d · ee32799d
Commit ee32799d authored Nov 17, 2017 by Martin Storsjo Committed by Alexandre Julliard Nov 17, 2017
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wcs.c dlls/msvcrt/wcs.c +4 -0

printf.c dlls/ucrtbase/tests/printf.c +11 -0

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--- a/dlls/msvcrt/wcs.c
+++ b/dlls/msvcrt/wcs.c
@@ -764,6 +764,8 @@ int CDECL MSVCRT__stdio_common_vsprintf( unsigned __int64 options, char *str, MS
            &ctx, format, locale, options & UCRTBASE_PRINTF_MASK, arg_clbk_valist, NULL, &valist);
    puts_clbk_str_a(&ctx, 1, &nullbyte);

+    if(!str)
+        return ret;
    if(options & UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION)
        return ret>len ? -1 : ret;
    if(ret>=len) {
@@ -1282,6 +1284,8 @@ int CDECL MSVCRT__stdio_common_vswprintf( unsigned __int64 options,
            &ctx, format, locale, options & UCRTBASE_PRINTF_MASK, arg_clbk_valist, NULL, &valist);
    puts_clbk_str_w(&ctx, 1, &nullbyte);

+    if(!str)
+        return ret;
    if(options & UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION)
        return ret>len ? -1 : ret;
    if(ret>=len) {

--- a/dlls/ucrtbase/tests/printf.c
+++ b/dlls/ucrtbase/tests/printf.c
@@ -215,6 +215,10 @@ static void test_snprintf (void)

    ok (vsprintf_wrapper (UCRTBASE_PRINTF_STANDARD_SNPRINTF_BEHAVIOUR, NULL, 0, "abcd") == 4,
        "Failure to snprintf to NULL\n");
+    ok (vsprintf_wrapper (UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION, NULL, 0, "abcd") == 4,
+        "Failure to snprintf to NULL\n");
+    ok (vsprintf_wrapper (0, NULL, 0, "abcd") == 4,
+        "Failure to snprintf to NULL\n");
 }

 static int WINAPIV vswprintf_wrapper(unsigned __int64 options, wchar_t *str,
@@ -289,6 +293,13 @@ static void test_swprintf (void)
        ok (buffer[valid] == '\0',
            "\"%s\": Missing null termination (ret %d) - is %d\n", narrow_fmt, n, buffer[valid]);
    }
+
+    ok (vswprintf_wrapper (UCRTBASE_PRINTF_STANDARD_SNPRINTF_BEHAVIOUR, NULL, 0, str_short) == 5,
+        "Failure to swprintf to NULL\n");
+    ok (vswprintf_wrapper (UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION, NULL, 0, str_short) == 5,
+        "Failure to swprintf to NULL\n");
+    ok (vswprintf_wrapper (0, NULL, 0, str_short) == 5,
+        "Failure to swprintf to NULL\n");
 }

 static int WINAPIV vfprintf_wrapper(FILE *file,