1 files changed, 50 insertions, 0 deletions
diff --git a/wcsmbs/tst-mbstowcs.c b/wcsmbs/tst-mbstowcs.c
new file mode 100644
index 0000000000..b48891553e
--- /dev/null
+++ b/wcsmbs/tst-mbstowcs.c
@@ -0,0 +1,50 @@
+/* Test basic mbstowcs including wstring == NULL (Bug 25219).
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+
+static int
+do_test (void)
+{
+  char string[] = { '1', '2', '3' , '4', '5', '\0' };
+  size_t len = strlen (string);
+  wchar_t wstring[] = { L'1', L'2', L'3', L'4', L'5', L'\0' };
+#define NUM_WCHAR 6
+  wchar_t wout[NUM_WCHAR];
+  size_t result;
+
+  /* The input ASCII string in the C/POSIX locale must convert
+     to the matching WSTRING.  */
+  result = mbstowcs (wout, string, NUM_WCHAR);
+  TEST_VERIFY (result == (NUM_WCHAR - 1));
+  TEST_COMPARE_BLOB (wstring, sizeof (wchar_t) * (NUM_WCHAR - 1),
+		     wout, sizeof (wchar_t) * result);
+
+  /* The input ASCII string in the C/POSIX locale must be the
+     same length when using mbstowcs to compute the length of
+     the string required in the conversion.  Using mbstowcs
+     in this way is an XSI extension to POSIX.  */
+  result = mbstowcs (NULL, string, len);
+  TEST_VERIFY (result == len);
+
+  return 0;
+}
+
+#include <support/test-driver.c>