printf should return negative value on error

[BZ #11741]
Fixed bug where printf and family may return a spurious success when
printing padded formats.

1 files changed, 26 insertions, 0 deletions

diff --git a/stdio-common/tst-put-error.c b/stdio-common/tst-put-error.c
index 115dbd509a..7b95491725 100644
--- a/stdio-common/tst-put-error.c
+++ b/stdio-common/tst-put-error.c
@@ -1,3 +1,22 @@
+/* Verify that print functions return error when there is an I/O error.
+
+   Copyright (C) 2005-2012 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 <errno.h>
 #include <error.h>
 #include <stdio.h>
@@ -26,6 +45,13 @@ do_test (void)
   printf ("fprintf = %d\n", n);
   if (n >= 0)
     error (EXIT_FAILURE, 0, "second fprintf succeeded");
+
+  /* Padded printing takes a different code path.  */
+  n = fprintf (fp, "%10000s", "foo");
+  printf ("fprintf = %d\n", n);
+  if (n >= 0)
+    error (EXIT_FAILURE, 0, "padded fprintf succeeded");
+
   return 0;
 }