1 files changed, 102 insertions, 0 deletions
diff --git a/libio/tst-sprintf-ub.c b/libio/tst-sprintf-ub.c
new file mode 100644
index 0000000000..24cba39ec6
--- /dev/null
+++ b/libio/tst-sprintf-ub.c
@@ -0,0 +1,102 @@
+/* Test the sprintf (buf, "%s", buf) does not override buf.
+   Copyright (C) 2019 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <support/check.h>
+
+enum
+{
+  FUNCTION_FIRST,
+  FUNCTION_SPRINTF = FUNCTION_FIRST,
+  FUNCTION_SNPRINF,
+  FUNCTION_VSPRINTF,
+  FUNCTION_VSNPRINTF,
+  FUNCTION_LAST
+};
+
+static void
+do_one_test (int function, char *buf, ...)
+{
+  va_list args;
+  char *arg;
+
+  /* Expected results for fortified and non-fortified sprintf.  */
+#if defined _FORTIFY_SOURCE && _FORTIFY_SOURCE > 1
+  const char *expected = "CD";
+#else
+  const char *expected = "ABCD";
+#endif
+
+  va_start (args, buf);
+  arg = va_arg (args, char *);
+  va_end (args);
+
+  switch (function)
+    {
+      /* The regular sprintf and vsprintf functions do not override the
+         destination buffer, even if source and destination overlap.  */
+      case FUNCTION_SPRINTF:
+        sprintf (buf, "%sCD", buf);
+        TEST_COMPARE_STRING (buf, expected);
+        break;
+      case FUNCTION_VSPRINTF:
+        va_start (args, buf);
+        vsprintf (arg, "%sCD", args);
+        TEST_COMPARE_STRING (arg, expected);
+        va_end (args);
+        break;
+      /* On the other hand, snprint and vsnprint override overlapping
+         source and destination buffers.  */
+      case FUNCTION_SNPRINF:
+        snprintf (buf, 3, "%sCD", buf);
+        TEST_COMPARE_STRING (buf, "CD");
+        break;
+      case FUNCTION_VSNPRINTF:
+        va_start (args, buf);
+        vsnprintf (arg, 3, "%sCD", args);
+        TEST_COMPARE_STRING (arg, "CD");
+        va_end (args);
+        break;
+      default:
+        support_record_failure ();
+    }
+}
+
+static int
+do_test (void)
+{
+  char buf[8];
+  int i;
+
+  /* For each function in the enum do:
+       - reset the buffer to the initial state "AB";
+       - call the function with buffer as source and destination;
+       - check for the desired behavior.  */
+  for (i = FUNCTION_FIRST; i < FUNCTION_LAST; i++)
+    {
+      strncpy (buf, "AB", 3);
+      do_one_test (i, buf, buf);
+    }
+
+  return 0;
+}
+
+#include <support/test-driver.c>