xref: /illumos-gate/usr/src/lib/libc/port/gen/strlcat.c (revision 7257d1b4)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include "lint.h"
30 #include <string.h>
31 #include <sys/types.h>
32 
33 /*
34  * Appends src to the dstsize buffer at dst. The append will never
35  * overflow the destination buffer and the buffer will always be null
36  * terminated. Never reference beyond &dst[dstsize-1] when computing
37  * the length of the pre-existing string.
38  */
39 
40 size_t
strlcat(char * dst,const char * src,size_t dstsize)41 strlcat(char *dst, const char *src, size_t dstsize)
42 {
43 	char *df = dst;
44 	size_t left = dstsize;
45 	size_t l1;
46 	size_t l2 = strlen(src);
47 	size_t copied;
48 
49 	while (left-- != 0 && *df != '\0')
50 		df++;
51 	l1 = df - dst;
52 	if (dstsize == l1)
53 		return (l1 + l2);
54 
55 	copied = l1 + l2 >= dstsize ? dstsize - l1 - 1 : l2;
56 	(void) memcpy(dst + l1, src, copied);
57 	dst[l1+copied] = '\0';
58 	return (l1 + l2);
59 }
60