1 files changed, 58 insertions, 0 deletions
diff --git a/lib/strlcat.c b/lib/strlcat.c
new file mode 100644
index 0000000..e3e29a7
--- /dev/null
+++ b/lib/strlcat.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+/* 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.
+ */
+
+/* adapted for Quagga from glibc patch submission originally from
+ * Florian Weimer <fweimer@redhat.com>, 2016-05-18 */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdint.h>
+#include <string.h>
+
+#ifndef HAVE_STRLCAT
+#undef strlcat
+
+size_t strlcat(char *__restrict dest,
+	       const char *__restrict src, size_t destsize);
+
+size_t strlcat(char *__restrict dest,
+	       const char *__restrict src, size_t destsize)
+{
+	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 (destsize == 0)
+		return src_length;
+
+	size_t dest_length = strnlen(dest, destsize);
+	if (dest_length != destsize) {
+		/* Copy at most the remaining number of characters in the
+		   destination buffer.  Leave for the NUL terminator.  */
+		size_t to_copy = destsize - 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.  */
+	_Static_assert(sizeof(uintptr_t) == sizeof(size_t),
+		       "theoretical maximum object size covers address space");
+	return dest_length + src_length;
+}
+#endif /* HAVE_STRLCAT */