[PATCH] ucrtbase: Add support for x mode in fopen

[Ted Lyngmo]

This fixes bug 51846: Standard library call fopen(..., "wx") not
recognized - causes destruction of data.

Signed-off-by: Ted Lyngmo <ted at lyncon.se>
---
 dlls/msvcrt/file.c         |  5 +++++
 dlls/ucrtbase/tests/misc.c | 25 +++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/dlls/msvcrt/file.c b/dlls/msvcrt/file.c
index b0eeaf2a351..3b36d087822 100644
--- a/dlls/msvcrt/file.c
+++ b/dlls/msvcrt/file.c
@@ -1586,6 +1586,11 @@ static int msvcrt_get_flags(const wchar_t* mode, int *open_flags, int* stream_fl
       *open_flags |=  _O_TEXT;
       *open_flags &= ~_O_BINARY;
       break;
+#if _MSVCR_VER>=140
+    case 'x':
+      *open_flags |= _O_EXCL;
+      break;
+#endif
     case 'D':
       *open_flags |= _O_TEMPORARY;
       break;
diff --git a/dlls/ucrtbase/tests/misc.c b/dlls/ucrtbase/tests/misc.c
index c2b6dc18d28..c16307ecccb 100644
--- a/dlls/ucrtbase/tests/misc.c
+++ b/dlls/ucrtbase/tests/misc.c
@@ -1539,6 +1539,30 @@ static void test_fenv(void)
     ok(!except, "expected 0, got %lx\n", except);
 }
 
+static void test_fopen_exclusive( void )
+{
+    static const char * const testfile = "fileexcl.tst";
+    FILE *fp;
+
+    fp = fopen(testfile, "wx");
+    ok(fp != NULL, "creating file with mode wx failed\n");
+    fclose(fp);
+
+    fp = fopen(testfile, "wx");
+    ok(fp == NULL, "overwrote existing file with mode wx\n");
+
+    unlink(testfile);
+
+    fp = fopen(testfile, "w+x");
+    ok(fp != NULL, "creating file with mode w+x failed\n");
+    fclose(fp);
+
+    fp = fopen(testfile, "w+x");
+    ok(fp == NULL, "overwrote existing file with mode w+x\n");
+
+    unlink(testfile);
+}
+
 START_TEST(misc)
 {
     int arg_c;
@@ -1580,4 +1604,5 @@ START_TEST(misc)
     test_clock();
     test_thread_storage();
     test_fenv();
+    test_fopen_exclusive();
 }
-- 
2.31.1