Function escape_backref

modules/mappers/mod_rewrite.c:729–761

* Escapes a backreference in a similar way as php's urlencode does. * Based on ap_os_escape_path in server/util.c */

 * Based on ap_os_escape_path in server/util.c
 */
static char *escape_backref(apr_pool_t *p, const char *path,
                            const char *escapeme, const char *noescapeme,
                            int flags)
{
    char *copy = apr_palloc(p, 3 * strlen(path) + 1);
    const unsigned char *s = (const unsigned char *)path;
    unsigned char *d = (unsigned char *)copy;
    int noplus = (flags & RULEFLAG_ESCAPENOPLUS) != 0;
    int ctls = (flags & RULEFLAG_ESCAPECTLS) != 0;
    unsigned char c;

    while ((c = *s)) {
        if (((ctls ? !TEST_CHAR(c, T_VCHAR_OBSTEXT) : !escapeme)
             || (escapeme && ap_strchr_c(escapeme, c)))
            && (!noescapeme || !ap_strchr_c(noescapeme, c))) {
            if (apr_isalnum(c) || c == '_') {
                *d++ = c;
            }
            else if (c == ' ' && !noplus) {
                *d++ = '+';
            }
            else {
                d = c2x(c, '%', d);
            }
        }
        else {
            *d++ = c;
        }
        ++s;
    }
    *d = '\0';
    return copy;
}

/*
 * escape absolute uri, which may or may not be path oriented.