request.c

                    now_merged = sec_ent[sec_idx];
                }

                last_walk = (walk_walked_t*)apr_array_push(cache->walked);
                last_walk->matched = sec_ent[sec_idx];
                last_walk->merged = now_merged;
            }

            /* If .htaccess files are enabled, check for one, provided we
             * have reached a real path.
             */
            do {  /* Not really a loop, just a break'able code block */

                ap_conf_vector_t *htaccess_conf = NULL;

                /* No htaccess in an incomplete root path,
                 * nor if it's disabled
                 */
                if (seg < startseg || (!opts.override 
                    && apr_is_empty_table(opts.override_list)
                    )) {
                    break;
                }


                res = ap_parse_htaccess(&htaccess_conf, r, opts.override,
                                        opts.override_opts, opts.override_list,
                                        r->filename, sconf->access_name);
                if (res) {
                    return res;
                }

                if (!htaccess_conf) {
                    break;
                }

                /* If we are still here, we found our htaccess.
                 *
                 * Calculate our full-context core opts & override.
                 */
                core_opts_merge(htaccess_conf, &opts);

                /* If we merged this same htaccess last time, reuse it...
                 * this wouldn't work except that we cache the htaccess
                 * sections for the lifetime of the request, so we match
                 * the same conf.  Good planning (no, pure luck ;)
                 */
                if (matches) {
                    if (last_walk->matched == htaccess_conf) {
                        now_merged = last_walk->merged;
                        ++last_walk;
                        --matches;
                        break;
                    }

                    /* We fell out of sync.  This is our own copy of walked,
                     * so truncate the remaining matches and reset
                     * remaining.
                     */
                    cache->walked->nelts -= matches;
                    matches = 0;
                    cached = 0;
                }

                if (now_merged) {
                    now_merged = ap_merge_per_dir_configs(r->pool,
                                                          now_merged,
                                                          htaccess_conf);
                }
                else {
                    now_merged = htaccess_conf;
                }

                last_walk = (walk_walked_t*)apr_array_push(cache->walked);
                last_walk->matched = htaccess_conf;
                last_walk->merged = now_merged;

            } while (0); /* Only one htaccess, not a real loop */

            /* That temporary trailing slash was useful, now drop it.
             */
            if (temp_slash) {
                r->filename[--filename_len] = '\0';
            }

            /* Time for all good things to come to an end?
             */
            if (!r->path_info || !*r->path_info) {
                break;
            }

            /* Now it's time for the next segment...
             * We will assume the next element is an end node, and fix it up
             * below as necessary...
             */

            seg_name = r->filename + filename_len;
            delim = strchr(r->path_info + (*r->path_info == '/' ? 1 : 0), '/');
            if (delim) {
                apr_size_t path_info_len = delim - r->path_info;
                *delim = '\0';
                memcpy(seg_name, r->path_info, path_info_len + 1);
                filename_len += path_info_len;
                r->path_info = delim;
                *delim = '/';
            }
            else {
                apr_size_t path_info_len = strlen(r->path_info);
                memcpy(seg_name, r->path_info, path_info_len + 1);
                filename_len += path_info_len;
                r->path_info += path_info_len;
            }
            if (*seg_name == '/')
                ++seg_name;

            /* If nothing remained but a '/' string, we are finished
             * XXX: NO WE ARE NOT!!!  Now process this puppy!!! */
            if (!*seg_name) {
                break;
            }

            /* First optimization;
             * If...we knew r->filename was a file, and
             * if...we have strict (case-sensitive) filenames, or
             *      we know the canonical_filename matches to _this_ name, and
             * if...we have allowed symlinks
             * skip the lstat and dummy up an APR_DIR value for thisinfo.
             */
            if (r->finfo.filetype != APR_NOFILE
#ifdef CASE_BLIND_FILESYSTEM
                && (filename_len <= canonical_len)
#endif
                && ((opts.opts & (OPT_SYM_OWNER | OPT_SYM_LINKS)) == OPT_SYM_LINKS))
            {

                thisinfo.filetype = APR_DIR;
                ++seg;
                continue;
            }

            /* We choose apr_stat with flag APR_FINFO_LINK here, rather that
             * plain apr_stat, so that we capture this path object rather than
             * its target.  We will replace the info with our target's info
             * below.  We especially want the name of this 'link' object, not
             * the name of its target, if we are fixing the filename
             * case/resolving aliases.
             */
            rv = ap_run_dirwalk_stat(&thisinfo, r,
                                     APR_FINFO_MIN | APR_FINFO_NAME | APR_FINFO_LINK);

            if (APR_STATUS_IS_ENOENT(rv)) {
                /* Nothing?  That could be nice.  But our directory
                 * walk is done.
                 */
                thisinfo.filetype = APR_NOFILE;
                break;
            }
            else if (APR_STATUS_IS_EACCES(rv)) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00035)
                              "access to %s denied (filesystem path '%s') "
                              "because search permissions are missing on a "
                              "component of the path", r->uri, r->filename);
                return r->status = HTTP_FORBIDDEN;
            }
            else if ((rv != APR_SUCCESS && rv != APR_INCOMPLETE)
                     || !(thisinfo.valid & APR_FINFO_TYPE)) {
                /* If we hit ENOTDIR, we must have over-optimized, deny
                 * rather than assume not found.
                 */
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r, APLOGNO(00036)
                              "access to %s failed (filesystem path '%s')", 
                              r->uri, r->filename);
                return r->status = HTTP_FORBIDDEN;
            }

            /* Fix up the path now if we have a name, and they don't agree
             */
            if ((thisinfo.valid & APR_FINFO_NAME)
                && strcmp(seg_name, thisinfo.name)) {
                /* TODO: provide users an option that an internal/external
                 * redirect is required here?  We need to walk the URI and
                 * filename in tandem to properly correlate these.
                 */
                strcpy(seg_name, thisinfo.name);
                filename_len = strlen(r->filename);
            }

            if (thisinfo.filetype == APR_LNK) {
                /* Is this a possibly acceptable symlink?
                 */
                if ((res = resolve_symlink(r->filename, &thisinfo,
                                           opts.opts, r->pool)) != OK) {
                    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00037)
                                  "Symbolic link not allowed "
                                  "or link target not accessible: %s",
                                  r->filename);
                    return r->status = res;
                }
            }

            /* Ok, we are done with the link's info, test the real target
             */
            if (thisinfo.filetype == APR_REG ||
                thisinfo.filetype == APR_NOFILE) {
                /* That was fun, nothing left for us here
                 */
                break;
            }
            else if (thisinfo.filetype != APR_DIR) {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00038)
                              "Forbidden: %s doesn't point to "
                              "a file or directory",
                              r->filename);
                return r->status = HTTP_FORBIDDEN;
            }

            ++seg;
        } while (thisinfo.filetype == APR_DIR);

        /* If we have _not_ optimized, this is the time to recover
         * the final stat result.
         */
        if (r->finfo.filetype == APR_NOFILE || r->finfo.filetype == APR_LNK) {
            r->finfo = thisinfo;
        }

        /* Now splice the saved path_info back onto any new path_info
         */
        if (save_path_info) {
            if (r->path_info && *r->path_info) {
                r->path_info = ap_make_full_path(r->pool, r->path_info,
                                                 save_path_info);
            }
            else {
                r->path_info = save_path_info;
            }
        }

        /*
         * Now we'll deal with the regexes, note we pick up sec_idx
         * where we left off (we gave up after we hit entry_core->r)
         */
        for (; sec_idx < num_sec; ++sec_idx) {

            int nmatch = 0;
            int i;
            ap_regmatch_t *pmatch = NULL;

            core_dir_config *entry_core;
            entry_core = ap_get_core_module_config(sec_ent[sec_idx]);

            if (!entry_core->r) {
                continue;
            }

            if (entry_core->refs && entry_core->refs->nelts) {
                if (!rxpool) {
                    apr_pool_create(&rxpool, r->pool);
                }
                nmatch = entry_core->refs->nelts;
                pmatch = apr_palloc(rxpool, nmatch*sizeof(ap_regmatch_t));
            }

            if (ap_regexec(entry_core->r, r->filename, nmatch, pmatch, 0)) {
                continue;
            }

            for (i = 0; i < nmatch; i++) {
                if (pmatch[i].rm_so >= 0 && pmatch[i].rm_eo >= 0 &&
                    ((const char **)entry_core->refs->elts)[i]) {
                    apr_table_setn(r->subprocess_env, 
                                   ((const char **)entry_core->refs->elts)[i],
                                   apr_pstrndup(r->pool,
                                   r->filename + pmatch[i].rm_so,
                                   pmatch[i].rm_eo - pmatch[i].rm_so));
                }
            }

            /* If we haven't already continue'd above, we have a match.
             *
             * Calculate our full-context core opts & override.
             */
            core_opts_merge(sec_ent[sec_idx], &opts);

            /* If we merged this same section last time, reuse it
             */
            if (matches) {
                if (last_walk->matched == sec_ent[sec_idx]) {
                    now_merged = last_walk->merged;
                    ++last_walk;
                    --matches;
                    continue;
                }

                /* We fell out of sync.  This is our own copy of walked,
                 * so truncate the remaining matches and reset remaining.
                 */
                cache->walked->nelts -= matches;
                matches = 0;
                cached = 0;
            }

            if (now_merged) {
                now_merged = ap_merge_per_dir_configs(r->pool,
                                                      now_merged,
                                                      sec_ent[sec_idx]);
            }
            else {
                now_merged = sec_ent[sec_idx];
            }

            last_walk = (walk_walked_t*)apr_array_push(cache->walked);
            last_walk->matched = sec_ent[sec_idx];
            last_walk->merged = now_merged;
        }

        if (rxpool) {
            apr_pool_destroy(rxpool);
        }

        /* Whoops - everything matched in sequence, but either the original
         * walk found some additional matches (which we need to truncate), or
         * this walk found some additional matches.
         */
        if (matches) {
            cache->walked->nelts -= matches;
            cached = 0;
        }
        else if (cache->walked->nelts > cached_matches) {
            cached = 0;
        }
    }

/* It seems this shouldn't be needed anymore.  We translated the
 x symlink above into a real resource, and should have died up there.
 x Even if we keep this, it needs more thought (maybe an r->file_is_symlink)
 x perhaps it should actually happen in file_walk, so we catch more
 x obscure cases in autoindex subrequests, etc.
 x
 x    * Symlink permissions are determined by the parent.  If the request is
 x    * for a directory then applying the symlink test here would use the
 x    * permissions of the directory as opposed to its parent.  Consider a
 x    * symlink pointing to a dir with a .htaccess disallowing symlinks.  If
 x    * you access /symlink (or /symlink/) you would get a 403 without this
 x    * APR_DIR test.  But if you accessed /symlink/index.html, for example,
 x    * you would *not* get the 403.
 x
 x   if (r->finfo.filetype != APR_DIR
 x       && (res = resolve_symlink(r->filename, r->info, ap_allow_options(r),
 x                                 r->pool))) {
 x       ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
 x                     "Symbolic link not allowed: %s", r->filename);
 x       return res;
 x   }
 */

    /* Save future sub-requestors much angst in processing
     * this subrequest.  If dir_walk couldn't canonicalize
     * the file path, nothing can.
     */
    r->canonical_filename = r->filename;

    if (r->finfo.filetype == APR_DIR) {
        cache->cached = r->filename;
    }
    else {
        cache->cached = ap_make_dirstr_parent(r->pool, r->filename);
    }

    if (cached
        && r->per_dir_config == cache->dir_conf_merged) {
        r->per_dir_config = cache->per_dir_result;
        return OK;
    }

    cache->dir_conf_tested = sec_ent;
    cache->dir_conf_merged = r->per_dir_config;

    /* Merge our cache->dir_conf_merged construct with the r->per_dir_configs,
     * and note the end result to (potentially) skip this step next time.
     */
    if (now_merged) {
        r->per_dir_config = ap_merge_per_dir_configs(r->pool,
                                                     r->per_dir_config,
                                                     now_merged);
    }
    cache->per_dir_result = r->per_dir_config;

    return OK;
}


AP_DECLARE(int) ap_location_walk(request_rec *r)
{
    ap_conf_vector_t *now_merged = NULL;
    core_server_config *sconf =
        ap_get_core_module_config(r->server->module_config);
    ap_conf_vector_t **sec_ent = (ap_conf_vector_t **)sconf->sec_url->elts;
    int num_sec = sconf->sec_url->nelts;
    walk_cache_t *cache;
    const char *entry_uri;
    int cached;

    /* No tricks here, there are no <Locations > to parse in this vhost.
     * We won't destroy the cache, just in case _this_ redirect is later
     * redirected again to a vhost with <Location > blocks to optimize.
     */
    if (!num_sec) {
        return OK;
    }

    cache = prep_walk_cache(AP_NOTE_LOCATION_WALK, r);
    cached = (cache->cached != NULL);

    /* Location and LocationMatch differ on their behaviour w.r.t. multiple
     * slashes.  Location matches multiple slashes with a single slash,
     * LocationMatch doesn't.  An exception, for backwards brokenness is
     * absoluteURIs... in which case neither match multiple slashes.
     */
    if (r->uri[0] != '/') {
        entry_uri = r->uri;
    }
    else {
        char *uri = apr_pstrdup(r->pool, r->uri);
        ap_no2slash(uri);
        entry_uri = uri;
    }

    /* If we have an cache->cached location that matches r->uri,
     * and the vhost's list of locations hasn't changed, we can skip
     * rewalking the location_walk entries.
     */
    if (cached
        && (cache->dir_conf_tested == sec_ent)
        && (strcmp(entry_uri, cache->cached) == 0)) {
        /* Well this looks really familiar!  If our end-result (per_dir_result)
         * didn't change, we have absolutely nothing to do :)
         * Otherwise (as is the case with most dir_merged/file_merged requests)
         * we must merge our dir_conf_merged onto this new r->per_dir_config.
         */
        if (r->per_dir_config == cache->per_dir_result) {
            return OK;
        }

        if (cache->walked->nelts) {
            now_merged = ((walk_walked_t*)cache->walked->elts)
                                            [cache->walked->nelts - 1].merged;
        }
    }
    else {
        /* We start now_merged from NULL since we want to build
         * a locations list that can be merged to any vhost.
         */
        int len, sec_idx;
        int matches = cache->walked->nelts;
        int cached_matches = matches;
        walk_walked_t *last_walk = (walk_walked_t*)cache->walked->elts;
        apr_pool_t *rxpool = NULL;

        cached &= auth_internal_per_conf;
        cache->cached = entry_uri;

        /* Go through the location entries, and check for matches.
         * We apply the directive sections in given order, we should
         * really try them with the most general first.
         */
        for (sec_idx = 0; sec_idx < num_sec; ++sec_idx) {

            core_dir_config *entry_core;
            entry_core = ap_get_core_module_config(sec_ent[sec_idx]);

            /* ### const strlen can be optimized in location config parsing */
            len = strlen(entry_core->d);

            /* Test the regex, fnmatch or string as appropriate.
             * If it's a strcmp, and the <Location > pattern was
             * not slash terminated, then this uri must be slash
             * terminated (or at the end of the string) to match.
             */
            if (entry_core->r) {

                int nmatch = 0;
                int i;
                ap_regmatch_t *pmatch = NULL;

                if (entry_core->refs && entry_core->refs->nelts) {
                    if (!rxpool) {
                        apr_pool_create(&rxpool, r->pool);
                    }
                    nmatch = entry_core->refs->nelts;
                    pmatch = apr_palloc(rxpool, nmatch*sizeof(ap_regmatch_t));
                }

                if (ap_regexec(entry_core->r, r->uri, nmatch, pmatch, 0)) {
                    continue;
                }

                for (i = 0; i < nmatch; i++) {
                    if (pmatch[i].rm_so >= 0 && pmatch[i].rm_eo >= 0 && 
                        ((const char **)entry_core->refs->elts)[i]) {
                        apr_table_setn(r->subprocess_env,
                                       ((const char **)entry_core->refs->elts)[i],
                                       apr_pstrndup(r->pool,
                                       r->uri + pmatch[i].rm_so,
                                       pmatch[i].rm_eo - pmatch[i].rm_so));
                    }
                }

            }
            else {

                if ((entry_core->d_is_fnmatch
                   ? apr_fnmatch(entry_core->d, cache->cached, APR_FNM_PATHNAME)
                   : (strncmp(entry_core->d, cache->cached, len)
                      || (len > 0
                          && entry_core->d[len - 1] != '/'
                          && cache->cached[len] != '/'
                          && cache->cached[len] != '\0')))) {
                    continue;
                }

            }

            /* If we merged this same section last time, reuse it
             */
            if (matches) {
                if (last_walk->matched == sec_ent[sec_idx]) {
                    now_merged = last_walk->merged;
                    ++last_walk;
                    --matches;
                    continue;
                }

                /* We fell out of sync.  This is our own copy of walked,
                 * so truncate the remaining matches and reset remaining.
                 */
                cache->walked->nelts -= matches;
                matches = 0;
                cached = 0;
            }

            if (now_merged) {
                now_merged = ap_merge_per_dir_configs(r->pool,
                                                      now_merged,
                                                      sec_ent[sec_idx]);
            }
            else {
                now_merged = sec_ent[sec_idx];
            }

            last_walk = (walk_walked_t*)apr_array_push(cache->walked);
            last_walk->matched = sec_ent[sec_idx];
            last_walk->merged = now_merged;
        }

        if (rxpool) {
            apr_pool_destroy(rxpool);
        }

        /* Whoops - everything matched in sequence, but either the original
         * walk found some additional matches (which we need to truncate), or
         * this walk found some additional matches.
         */
        if (matches) {
            cache->walked->nelts -= matches;
            cached = 0;
        }
        else if (cache->walked->nelts > cached_matches) {
            cached = 0;
        }
    }

    if (cached
        && r->per_dir_config == cache->dir_conf_merged) {
        r->per_dir_config = cache->per_dir_result;
        return OK;
    }

    cache->dir_conf_tested = sec_ent;
    cache->dir_conf_merged = r->per_dir_config;

    /* Merge our cache->dir_conf_merged construct with the r->per_dir_configs,
     * and note the end result to (potentially) skip this step next time.
     */
    if (now_merged) {
        r->per_dir_config = ap_merge_per_dir_configs(r->pool,
                                                     r->per_dir_config,
                                                     now_merged);
    }
    cache->per_dir_result = r->per_dir_config;

    return OK;
}

AP_DECLARE(int) ap_file_walk(request_rec *r)
{
    ap_conf_vector_t *now_merged = NULL;
    core_dir_config *dconf = ap_get_core_module_config(r->per_dir_config);
    ap_conf_vector_t **sec_ent = NULL;
    int num_sec = 0;
    walk_cache_t *cache;
    const char *test_file;
    int cached;

    if (dconf->sec_file) {
        sec_ent = (ap_conf_vector_t **)dconf->sec_file->elts;
        num_sec = dconf->sec_file->nelts;
    }

    /* To allow broken modules to proceed, we allow missing filenames to pass.
     * We will catch it later if it's heading for the core handler.
     * directory_walk already posted an INFO note for module debugging.
     */
    if (r->filename == NULL) {
        return OK;
    }

    /* No tricks here, there are just no <Files > to parse in this context.
     * We won't destroy the cache, just in case _this_ redirect is later
     * redirected again to a context containing the same or similar <Files >.
     */
    if (!num_sec) {
        return OK;
    }

    cache = prep_walk_cache(AP_NOTE_FILE_WALK, r);
    cached = (cache->cached != NULL);

    /* Get the basename .. and copy for the cache just
     * in case r->filename is munged by another module
     */
    test_file = strrchr(r->filename, '/');
    if (test_file == NULL) {
        test_file = apr_pstrdup(r->pool, r->filename);
    }
    else {
        test_file = apr_pstrdup(r->pool, ++test_file);
    }

    /* If we have an cache->cached file name that matches test_file,
     * and the directory's list of file sections hasn't changed, we
     * can skip rewalking the file_walk entries.
     */
    if (cached
        && (cache->dir_conf_tested == sec_ent)
        && (strcmp(test_file, cache->cached) == 0)) {
        /* Well this looks really familiar!  If our end-result (per_dir_result)
         * didn't change, we have absolutely nothing to do :)
         * Otherwise (as is the case with most dir_merged requests)
         * we must merge our dir_conf_merged onto this new r->per_dir_config.
         */
        if (r->per_dir_config == cache->per_dir_result) {
            return OK;
        }

        if (cache->walked->nelts) {
            now_merged = ((walk_walked_t*)cache->walked->elts)
                [cache->walked->nelts - 1].merged;
        }
    }
    else {
        /* We start now_merged from NULL since we want to build
         * a file section list that can be merged to any dir_walk.
         */
        int sec_idx;
        int matches = cache->walked->nelts;
        int cached_matches = matches;
        walk_walked_t *last_walk = (walk_walked_t*)cache->walked->elts;
        apr_pool_t *rxpool = NULL;

        cached &= auth_internal_per_conf;
        cache->cached = test_file;

        /* Go through the location entries, and check for matches.
         * We apply the directive sections in given order, we should
         * really try them with the most general first.
         */
        for (sec_idx = 0; sec_idx < num_sec; ++sec_idx) {
            core_dir_config *entry_core;
            entry_core = ap_get_core_module_config(sec_ent[sec_idx]);

            if (entry_core->r) {

                int nmatch = 0;
                int i;
                ap_regmatch_t *pmatch = NULL;

                if (entry_core->refs && entry_core->refs->nelts) {
                    if (!rxpool) {
                        apr_pool_create(&rxpool, r->pool);
                    }
                    nmatch = entry_core->refs->nelts;
                    pmatch = apr_palloc(rxpool, nmatch*sizeof(ap_regmatch_t));
                }

                if (ap_regexec(entry_core->r, cache->cached, nmatch, pmatch, 0)) {
                    continue;
                }

                for (i = 0; i < nmatch; i++) {
                    if (pmatch[i].rm_so >= 0 && pmatch[i].rm_eo >= 0 && 
                        ((const char **)entry_core->refs->elts)[i]) {
                        apr_table_setn(r->subprocess_env,
                                       ((const char **)entry_core->refs->elts)[i],
                                       apr_pstrndup(r->pool,
                                       cache->cached + pmatch[i].rm_so,
                                       pmatch[i].rm_eo - pmatch[i].rm_so));
                    }
                }

            }
            else {
                if ((entry_core->d_is_fnmatch
                       ? apr_fnmatch(entry_core->d, cache->cached, APR_FNM_PATHNAME)
                       : strcmp(entry_core->d, cache->cached))) {
                    continue;
                }
            }

            /* If we merged this same section last time, reuse it
             */
            if (matches) {
                if (last_walk->matched == sec_ent[sec_idx]) {
                    now_merged = last_walk->merged;
                    ++last_walk;
                    --matches;
                    continue;
                }

                /* We fell out of sync.  This is our own copy of walked,
                 * so truncate the remaining matches and reset remaining.
                 */
                cache->walked->nelts -= matches;
                matches = 0;
                cached = 0;
            }

            if (now_merged) {
                now_merged = ap_merge_per_dir_configs(r->pool,
                                                      now_merged,
                                                      sec_ent[sec_idx]);
            }
            else {
                now_merged = sec_ent[sec_idx];
            }

            last_walk = (walk_walked_t*)apr_array_push(cache->walked);
            last_walk->matched = sec_ent[sec_idx];
            last_walk->merged = now_merged;
        }

        if (rxpool) {
            apr_pool_destroy(rxpool);
        }

        /* Whoops - everything matched in sequence, but either the original
         * walk found some additional matches (which we need to truncate), or
         * this walk found some additional matches.
         */
        if (matches) {
            cache->walked->nelts -= matches;
            cached = 0;
        }
        else if (cache->walked->nelts > cached_matches) {
            cached = 0;
        }
    }

    if (cached
        && r->per_dir_config == cache->dir_conf_merged) {
        r->per_dir_config = cache->per_dir_result;
        return OK;
    }

    cache->dir_conf_tested = sec_ent;
    cache->dir_conf_merged = r->per_dir_config;

    /* Merge our cache->dir_conf_merged construct with the r->per_dir_configs,
     * and note the end result to (potentially) skip this step next time.
     */
    if (now_merged) {
        r->per_dir_config = ap_merge_per_dir_configs(r->pool,
                                                     r->per_dir_config,
                                                     now_merged);
    }
    cache->per_dir_result = r->per_dir_config;

    return OK;
}

static int ap_if_walk_sub(request_rec *r, core_dir_config* dconf)
{
    ap_conf_vector_t *now_merged = NULL;
    ap_conf_vector_t **sec_ent = NULL;
    int num_sec = 0;
    walk_cache_t *cache;
    int cached;
    int sec_idx;
    int matches;
    int cached_matches;
    int prev_result = -1;
    walk_walked_t *last_walk;

    if (dconf && dconf->sec_if) {
        sec_ent = (ap_conf_vector_t **)dconf->sec_if->elts;
        num_sec = dconf->sec_if->nelts;
    }

    /* No tricks here, there are just no <If > to parse in this context.
     * We won't destroy the cache, just in case _this_ redirect is later
     * redirected again to a context containing the same or similar <If >.
     */
    if (!num_sec) {
        return OK;
    }

    cache = prep_walk_cache(AP_NOTE_IF_WALK, r);
    cached = (cache->cached != NULL);
    cache->cached = (void *)1;
    matches = cache->walked->nelts;
    cached_matches = matches;
    last_walk = (walk_walked_t*)cache->walked->elts;

    cached &= auth_internal_per_conf;

    /* Go through the if entries, and check for matches  */
    for (sec_idx = 0; sec_idx < num_sec; ++sec_idx) {
        const char *err = NULL;
        core_dir_config *entry_core;
        int rc;
        entry_core = ap_get_core_module_config(sec_ent[sec_idx]);

        AP_DEBUG_ASSERT(entry_core->condition_ifelse != 0);
        if (entry_core->condition_ifelse & AP_CONDITION_ELSE) {
            AP_DEBUG_ASSERT(prev_result != -1);
            if (prev_result == 1)
                continue;
        }

        if (entry_core->condition_ifelse & AP_CONDITION_IF) {
            rc = ap_expr_exec(r, entry_core->condition, &err);
            if (rc <= 0) {
                if (rc < 0)
                    ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(00039)
                                  "Failed to evaluate <If > condition: %s",
                                  err);
                prev_result = 0;
                continue;
            }
            prev_result = 1;
        }
        else {
            prev_result = -1;
        }

        /* If we merged this same section last time, reuse it
         */
        if (matches) {
            if (last_walk->matched == sec_ent[sec_idx]) {
                now_merged = last_walk->merged;
                ++last_walk;
                --matches;
                continue;
            }

            /* We fell out of sync.  This is our own copy of walked,
             * so truncate the remaining matches and reset remaining.
             */
            cache->walked->nelts -= matches;
            matches = 0;
            cached = 0;
        }

        if (now_merged) {
            now_merged = ap_merge_per_dir_configs(r->pool,
                                                  now_merged,
                                                  sec_ent[sec_idx]);
        }
        else {
            now_merged = sec_ent[sec_idx];
        }

        last_walk = (walk_walked_t*)apr_array_push(cache->walked);
        last_walk->matched = sec_ent[sec_idx];
        last_walk->merged = now_merged;
    }

    /* Everything matched in sequence, but it may be that the original
     * walk found some additional matches (which we need to truncate), or
     * this walk found some additional matches.
     */
    if (matches) {
        cache->walked->nelts -= matches;
        cached = 0;
    }
    else if (cache->walked->nelts > cached_matches) {
        cached = 0;
    }

    if (cached
        && r->per_dir_config == cache->dir_conf_merged) {
        r->per_dir_config = cache->per_dir_result;
        return OK;
    }

    cache->dir_conf_tested = sec_ent;
    cache->dir_conf_merged = r->per_dir_config;

    /* Merge our cache->dir_conf_merged construct with the r->per_dir_configs,
     * and note the end result to (potentially) skip this step next time.
     */
    if (now_merged) {
        r->per_dir_config = ap_merge_per_dir_configs(r->pool,
                                                     r->per_dir_config,
                                                     now_merged);
    }
    cache->per_dir_result = r->per_dir_config;

    if (now_merged) {
        core_dir_config *dconf_merged = ap_get_core_module_config(now_merged);

        /* Allow nested <If>s and their configs to get merged
         * with the current one.
         */
        return ap_if_walk_sub(r, dconf_merged);
    }

    return OK;
}

AP_DECLARE(int) ap_if_walk(request_rec *r)
{
    core_dir_config *dconf = ap_get_core_module_config(r->per_dir_config);
    int status = ap_if_walk_sub(r, dconf);
    return status;
}

/*****************************************************************
 *
 * The sub_request mechanism.
 *
 * Fns to look up a relative URI from, e.g., a map file or SSI document.
 * These do all access checks, etc., but don't actually run the transaction
 * ... use run_sub_req below for that.  Also, be sure to use destroy_sub_req
 * as appropriate if you're likely to be creating more than a few of these.
 * (An early Apache version didn't destroy the sub_reqs used in directory
 * indexing.  The result, when indexing a directory with 800-odd files in
 * it, was massively excessive storage allocation).
 *
 * Note more manipulation of protocol-specific vars in the request
 * structure...
 */

static request_rec *make_sub_request(const request_rec *r,
                                     ap_filter_t *next_filter)
{
    apr_pool_t *rrp;
    request_rec *rnew;

    apr_pool_create(&rrp, r->pool);
    apr_pool_tag(rrp, "subrequest");
    rnew = apr_pcalloc(rrp, sizeof(request_rec));
    rnew->pool = rrp;

    rnew->hostname       = r->hostname;
    rnew->request_time   = r->request_time;
    rnew->connection     = r->connection;
    rnew->server         = r->server;
    rnew->log            = r->log;

    rnew->request_config = ap_create_request_config(rnew->pool);

    /* Start a clean config from this subrequest's vhost.  Optimization in
     * Location/File/Dir walks from the parent request assure that if the
     * config blocks of the subrequest match the parent request, no merges
     * will actually occur (and generally a minimal number of merges are
     * required, even if the parent and subrequest aren't quite identical.)
     */
    rnew->per_dir_config = r->server->lookup_defaults;

    rnew->htaccess = r->htaccess;
    rnew->allowed_methods = ap_make_method_list(rnew->pool, 2);

    /* make a copy of the allowed-methods list */
    ap_copy_method_list(rnew->allowed_methods, r->allowed_methods);

    /* start with the same set of output filters */
    if (next_filter) {
        ap_filter_t *scan = next_filter;

        /* while there are no input filters for a subrequest, we will
         * try to insert some, so if we don't have valid data, the code
         * will seg fault.
         */
        rnew->input_filters = r->input_filters;
        rnew->proto_input_filters = r->proto_input_filters;
        rnew->output_filters = next_filter;
        rnew->proto_output_filters = r->proto_output_filters;
        while (scan && (scan != r->proto_output_filters)) {
            if (scan->frec == ap_subreq_core_filter_handle) {