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strlcat.c (1767B)


      1 #ifndef __OpenBSD__
      2 /*	$OpenBSD: strlcat.c,v 1.19 2019/01/25 00:19:25 millert Exp $	*/
      3 
      4 /*
      5  * Copyright (c) 1998, 2015 Todd C. Miller <millert@openbsd.org>
      6  *
      7  * Permission to use, copy, modify, and distribute this software for any
      8  * purpose with or without fee is hereby granted, provided that the above
      9  * copyright notice and this permission notice appear in all copies.
     10  *
     11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
     12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     18  */
     19 
     20 #include <sys/types.h>
     21 #include <string.h>
     22 
     23 /*
     24  * Appends src to string dst of size dsize (unlike strncat, dsize is the
     25  * full size of dst, not space left).  At most dsize-1 characters
     26  * will be copied.  Always NUL terminates (unless dsize <= strlen(dst)).
     27  * Returns strlen(src) + MIN(dsize, strlen(initial dst)).
     28  * If retval >= dsize, truncation occurred.
     29  */
     30 size_t
     31 strlcat(char *dst, const char *src, size_t dsize)
     32 {
     33 	const char *odst = dst;
     34 	const char *osrc = src;
     35 	size_t n = dsize;
     36 	size_t dlen;
     37 
     38 	/* Find the end of dst and adjust bytes left but don't go past end. */
     39 	while (n-- != 0 && *dst != '\0')
     40 		dst++;
     41 	dlen = dst - odst;
     42 	n = dsize - dlen;
     43 
     44 	if (n-- == 0)
     45 		return(dlen + strlen(src));
     46 	while (*src != '\0') {
     47 		if (n != 0) {
     48 			*dst++ = *src;
     49 			n--;
     50 		}
     51 		src++;
     52 	}
     53 	*dst = '\0';
     54 
     55 	return(dlen + (src - osrc));	/* count does not include NUL */
     56 }
     57 #endif