strlcat and strlcpy functions derived from OpenBSD libc

strl.c

#include <string.h>

size_t
strlcat(char *dst, const char *src, size_t dsize) {
    const char *odst = dst;
    const char *osrc = src;
    size_t count = dsize;
    size_t length;

    if ((dst == NULL) ||
            (src == NULL)) {
        return 0;
    }
    while ((count-- != 0) &&
            (*dst != '\0')) {
        dst++;
    }
    length = dst - odst;
    count = dsize - length;

    if (count-- == 0) {
        return (length + strlen(src));
    }
    while (*src != '\0') {
        if (count != 0) {
            *dst++ = *src;
            count--;
        }
        src++;
    }
    *dst = '\0';

    return (length + (src - osrc));
}

size_t
strlcpy(char *dst, const char *src, size_t dsize) {
    const char *osrc = src;
    size_t count = dsize;

    if ((dst == NULL) ||
            (src == NULL)) {
        return 0;
    }
    if (count != 0) {
        while (--count != 0) {
            if ((*dst++ = *src++) == '\0') {
                break;
            }
        }
    }
    if (count == 0) {
        if (dsize != 0) {
            *dst = '\0';
        }
        while (*src++);
    }

    return (src - osrc - 1);
}