Function prefix_stat

modules/mappers/mod_rewrite.c:1004–1069

* stat() only the first segment of a path, and only if it matches the output of the last matching rule */

 * stat() only the first segment of a path, and only if it matches the output of the last matching rule
 */
static int prefix_stat(request_rec *r, const char *path, apr_pool_t *pool, rewriterule_entry *lastsub)
{
    const char *curpath = path;
    const char *root;
    const char *slash;
    char *statpath;
    apr_status_t rv;

    rv = apr_filepath_root(&root, &curpath, APR_FILEPATH_TRUENAME, pool);

    if (rv != APR_SUCCESS) {
        return 0;
    }

    /* let's recognize slashes only, the mod_rewrite semantics are opaque
     * enough.
     */
    if ((slash = ap_strchr_c(curpath, '/')) != NULL) {
        rv = apr_filepath_merge(&statpath, root,
                                apr_pstrndup(pool, curpath,
                                             (apr_size_t)(slash - curpath)),
                                APR_FILEPATH_NOTABOVEROOT |
                                APR_FILEPATH_NOTRELATIVE, pool);
    }
    else {
        rv = apr_filepath_merge(&statpath, root, curpath,
                                APR_FILEPATH_NOTABOVEROOT |
                                APR_FILEPATH_NOTRELATIVE, pool);
    }

    if (rv == APR_SUCCESS) {
        apr_finfo_t sb;

        if (apr_stat(&sb, statpath, APR_FINFO_MIN, pool) == APR_SUCCESS) {
            if (!lastsub) {
                rewritelog(r, 3, NULL, "prefix_stat no lastsub subst prefix %s", statpath);
                return 1;
            }

            rewritelog(r, 3, NULL, "prefix_stat compare statpath %s and lastsub output %s STATOK %d ",
                    statpath, lastsub->output, lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT);
            if (lastsub->flags & RULEFLAG_UNSAFE_PREFIX_STAT) {
                return 1;
            }
            else {
                const char *docroot = ap_document_root(r);
                const char *context_docroot = ap_context_document_root(r);
                /*
                 * As an example, path (r->filename) is /var/foo/bar/baz.html
                 * even if the flag is not set,  we can accept a rule that
                 * began with a literal /var (stapath), or if the entire path
                 * starts with the docroot or context document root
                 */
                if (startsWith(r, lastsub->output, statpath) ||
                        startsWith(r, path, docroot) ||
                        ((docroot != context_docroot) &&
                          startsWith(r, path, context_docroot))) {
                    return 1;