Add an implementation of strdup() to libkern. Allocated memory is of

type M_STRING, now defined in malloc.h.  Useful when string parsing
must occur using the kernel strsep() and we want to avoid toasting
the source string.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories

sys/conf/files

@@ -1130,6 +1130,7 @@ libkern/skpc.c		standard
 libkern/strcat.c	standard
 libkern/strcmp.c	standard
 libkern/strcpy.c	standard
+libkern/strdup.c	standard
 libkern/strlcat.c	standard
 libkern/strlcpy.c	standard
 libkern/strlen.c	standard

sys/libkern/strdup.c

@@ -0,0 +1,54 @@
+/*-
+ * Copyright (c) 2003 Networks Associates Technology, Inc.
+ * All rights reserved.
+ *
+ * This software was developed for the FreeBSD Project by NAI Labs,
+ * the Security Research Division of Network Associates, Inc. under
+ * DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA
+ * CHATS research program.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the authors may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/libkern.h>
+#include <sys/malloc.h>
+
+MALLOC_DEFINE(M_STRING, "string", "string buffers");
+
+char *
+strdup(const char *string)
+{
+	size_t len;
+	char *copy;
+
+	len = strlen(string) + 1;
+	copy = malloc(len, M_STRING, M_WAITOK);
+	bcopy(string, copy, len);
+	return (copy);
+}

sys/sys/libkern.h

@@ -92,6 +92,7 @@ void	 srandom(u_long);
 char	*strcat(char * __restrict, const char * __restrict);
 int	 strcmp(const char *, const char *);
 char	*strcpy(char * __restrict, const char * __restrict);
+char	*strdup(const char *__restrict);
 size_t	 strlcat(char *, const char *, size_t);
 size_t	 strlcpy(char *, const char *, size_t);
 size_t	 strlen(const char *);

sys/sys/malloc.h

@@ -79,6 +79,7 @@ struct malloc_type {
 
 MALLOC_DECLARE(M_CACHE);
 MALLOC_DECLARE(M_DEVBUF);
+MALLOC_DECLARE(M_STRING);
 MALLOC_DECLARE(M_TEMP);
 
 MALLOC_DECLARE(M_IP6OPT); /* for INET6 */