Libc-498.tar.gz

[apple/libc.git] / secure / strcat_chk.c

diff --git a/secure/strcat_chk.c b/secure/strcat_chk.c
new file mode 100644 (file)
index 0000000..e0ace2b
--- /dev/null
+++ b/secure/strcat_chk.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2007 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+extern void __chk_fail (void) __attribute__((__noreturn__));
+
+char *
+__strcat_chk (char *__restrict s, const char *__restrict append,
+             size_t slen)
+{
+  char *save = s;
+
+  /* Advance to the end. */
+  for (; *s; ++s)
+    if (__builtin_expect (slen-- == 0, 0))
+      __chk_fail ();
+
+  do
+    {
+      /* Append the string.  Make sure we check before writing.  */
+      if (__builtin_expect (slen-- == 0, 0))
+       __chk_fail ();
+
+    } while (*s++ = *append++);
+
+  return save;
+
+}