lib: replace strlcpy & strlcat with glibc versions

It seems these two were at some point copied in from rsync; replace with
more recent versions that will hopefully become available in glibc as
well.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 71 insertions, 0 deletions

diff --git a/lib/strlcat.c b/lib/strlcat.c
new file mode 100644
index 0000000000..1d04b43d95
--- /dev/null
+++ b/lib/strlcat.c
@@ -0,0 +1,71 @@
+/* Append a null-terminated string to another string, with length checking.
+   Copyright (C) 2016 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/>.  */
+
+/* adapted for Quagga from glibc patch submission originally from
+ * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "config.h"
+
+#ifndef HAVE_STRLCAT
+#undef strlcat
+
+size_t
+strlcat (char *__restrict dest, const char *__restrict src, size_t size);
+
+size_t
+strlcat (char *__restrict dest, const char *__restrict src, size_t size)
+{
+  size_t src_length = strlen (src);
+
+  /* Our implementation strlcat supports dest == NULL if size == 0
+     (for consistency with snprintf and strlcpy), but strnlen does
+     not, so we have to cover this case explicitly.  */
+  if (size == 0)
+    return src_length;
+
+  size_t dest_length = strnlen (dest, size);
+  if (dest_length != size)
+    {
+      /* Copy at most the remaining number of characters in the
+	 destination buffer.  Leave for the NUL terminator.  */
+      size_t to_copy = size - dest_length - 1;
+      /* But not more than what is available in the source string.  */
+      if (to_copy > src_length)
+	to_copy = src_length;
+
+      char *target = dest + dest_length;
+      memcpy (target, src, to_copy);
+      target[to_copy] = '\0';
+    }
+
+  /* If the sum wraps around, we have more than SIZE_MAX + 2 bytes in
+     the two input strings (including both null terminators).  If each
+     byte in the address space can be assigned a unique size_t value
+     (which the static_assert checks), then by the pigeonhole
+     principle, the two input strings must overlap, which is
+     undefined.  */
+#if __STDC_VERSION__ >= 201112L
+  _Static_assert (sizeof (uintptr_t) == sizeof (size_t),
+		  "theoretical maximum object size covers address space");
+#endif
+  return dest_length + src_length;
+}
+#endif /* HAVE_STRLCAT */