strlcpy.c (1620B) - raw

      1 /*	$OpenBSD: strlcpy.c,v 1.12 2015/01/15 03:54:12 millert Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com>
      5  *
      6  * Permission to use, copy, modify, and distribute this software for any
      7  * purpose with or without fee is hereby granted, provided that the above
      8  * copyright notice and this permission notice appear in all copies.
      9  *
     10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
     11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     17  */
     18 
     19 #include <sys/types.h>
     20 #include <string.h>
     21 
     22 #include "compat.h"
     23 
     24 /*
     25  * Copy string src to buffer dst of size dsize.  At most dsize-1
     26  * chars will be copied.  Always NUL terminates (unless dsize == 0).
     27  * Returns strlen(src); if retval >= dsize, truncation occurred.
     28  */
     29 size_t
     30 strlcpy(char *dst, const char *src, size_t dsize)
     31 {
     32 	const char *osrc = src;
     33 	size_t nleft = dsize;
     34 
     35 	/* Copy as many bytes as will fit. */
     36 	if (nleft != 0) {
     37 		while (--nleft != 0) {
     38 			if ((*dst++ = *src++) == '\0')
     39 				break;
     40 		}
     41 	}
     42 
     43 	/* Not enough room in dst, add NUL and traverse rest of src. */
     44 	if (nleft == 0) {
     45 		if (dsize != 0)
     46 			*dst = '\0';		/* NUL-terminate dst */
     47 		while (*src++)
     48 			;
     49 	}
     50 
     51 	return(src - osrc - 1);	/* count does not include NUL */
     52 }