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-rw-r--r--lib/strlcat.c71
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diff --git a/lib/strlcat.c b/lib/strlcat.c
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+/* 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 */
+
+#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 */