urlescap.c

static char *url_escape(char *path, int len) {
    char *org_path = strdup(path);
    memset(path, 0, len);
    char *enc = path;
    for (char *s = org_path; *s && (enc - path < len - 3); s++) {
        if (strchr("!*'();:@&=+$,/?%%#[]", *s) != NULL) {
            sprintf(enc, "%%%02X", *s);
        } else {
            sprintf(enc, "%c", *s);
        }
        while (*++enc);
    }
    free(org_path);
    return path;
}