dash/strlcpy.h

/*
 * Copyright (c) 1998 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.
 */

/*
 * Copy src to string dst of size siz.  At most siz-1 characters
 * will be copied.  Always NUL terminates (unless siz == 0).
 * Returns strlen(src); if retval >= siz, truncation occurred.
 */
inline size_t strlcpy(char *dst, const char *src, size_t siz)
{
    char *d = dst;
    const char *s = src;
    size_t n = siz;

    /* Copy as many bytes as will fit */
    if (n != 0)
    {
        while (--n != 0)
        {
            if ((*d++ = *s++) == '\0')
                break;
        }
    }

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

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

/*
 * Appends src to string dst of size siz (unlike strncat, siz is the
 * full size of dst, not space left).  At most siz-1 characters
 * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
 * Returns strlen(src) + MIN(siz, strlen(initial dst)).
 * If retval >= siz, truncation occurred.
 */
inline size_t strlcat(char *dst, const char *src, size_t siz)
{
    char *d = dst;
    const char *s = src;
    size_t n = siz;
    size_t dlen;

    /* Find the end of dst and adjust bytes left but don't go past end */
    while (n-- != 0 && *d != '\0')
        d++;
    dlen = d - dst;
    n = siz - dlen;

    if (n == 0)
        return(dlen + strlen(s));
    while (*s != '\0')
    {
        if (n != 1)
        {
            *d++ = *s;
            n--;
        }
        s++;
    }
    *d = '\0';

    return(dlen + (s - src)); /* count does not include NUL */
}