strlcpy.c

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/*      $OpenBSD: strlcpy.c,v 1.12 2015/01/15 03:54:12 millert Exp $    */

/*
 * Copyright (c) 1998, 2015 Todd C. Miller <Todd.Miller@courtesan.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "ruby/missing.h"
#include <sys/types.h>
#include <string.h>

/*
 * Copy string src to buffer dst of size dsize.  At most dsize-1
 * chars will be copied.  Always NUL terminates (unless dsize == 0).
 * Returns strlen(src); if retval >= dsize, truncation occurred.
 */
size_t
strlcpy(char *dst, const char *src, size_t dsize)
{
        const char *osrc = src;
        size_t nleft = dsize;

        /* Copy as many bytes as will fit. */
        if (nleft != 0) {
                while (--nleft != 0) {
                        if ((*dst++ = *src++) == '\0')
                                break;
                }
        }

        /* Not enough room in dst, add NUL and traverse rest of src. */
        if (nleft == 0) {
                if (dsize != 0)
                        *dst = '\0';            /* NUL-terminate dst */
                while (*src++)
                        ;
        }

        return(src - osrc - 1); /* count does not include NUL */
}