Strtok.c

__strtok_r(char *s, const char *delim, char **last)
{
    char *spanp, *tok;
    int c, sc;
 
    if (s == NULL && (s = *last) == NULL)
        return (NULL);
 
    /*
     * Skip (span) leading delimiters (s += strspn(s, delim), sort of).
     */
cont:
    c = *s++;
    for (spanp = (char *)delim; (sc = *spanp++) != 0;) {
        if (c == sc)
            goto cont;
    }
 
    if (c == 0) {       /* no non-delimiter characters */
        *last = NULL;
        return (NULL);
    }
    tok = s - 1;
 
    /*
     * Scan token (scan for delimiters: s += strcspn(s, delim), sort of).
     * Note that delim must have one NUL; we stop if we see that, too.
     */
    for (;;) {
        c = *s++;
        spanp = (char *)delim;
        do {
            if ((sc = *spanp++) == c) {
                if (c == 0)
                    s = NULL;
                else
                    s[-1] = '\0';
                *last = s;
                return (tok);
            }
        } while (sc != 0);
    }
    /* NOTREACHED */
}