modules/cache/mod_file_cache.c - httpd - Git at Google

 /* Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 /*
  * Author: mod_file_cache by Bill Stoddard <stoddard apache.org>
  *         Based on mod_mmap_static by Dean Gaudet <dgaudet arctic.org>
  *
  * v0.01: initial implementation
  */

 /*
     Documentation:

     Some sites have a set of static files that are really busy, and
     change infrequently (or even on a regular schedule). Save time
     by caching open handles to these files. This module, unlike
     mod_mmap_static, caches open file handles, not file content.
     On systems (like Windows) with heavy system call overhead and
     that have an efficient sendfile implementation, caching file handles
     offers several advantages over caching content. First, the file system
     can manage the memory, allowing infrequently hit cached files to
     be paged out. Second, since caching open handles does not consume
     significant resources, it will be possible to enable an AutoLoadCache
     feature where static files are dynamically loaded in the cache
     as the server runs. On systems that have file change notification,
     this module can be enhanced to automatically garbage collect
     cached files that change on disk.

     This module should work on Unix systems that have sendfile. Place
     cachefile directives into your configuration to direct files to
     be cached.

         cachefile /path/to/file1
         cachefile /path/to/file2
         ...

     These files are only cached when the server is restarted, so if you
     change the list, or if the files are changed, then you'll need to
     restart the server.

     To reiterate that point:  if the files are modified *in place*
     without restarting the server you may end up serving requests that
     are completely bogus.  You should update files by unlinking the old
     copy and putting a new copy in place.

     There's no such thing as inheriting these files across vhosts or
     whatever... place the directives in the main server only.

     Known problems:

     Don't use Alias or RewriteRule to move these files around...  unless
     you feel like paying for an extra stat() on each request.  This is
     a deficiency in the Apache API that will hopefully be solved some day.
     The file will be served out of the file handle cache, but there will be
     an extra stat() that's a waste.
 */

 #include "apr.h"

 #if !(APR_HAS_SENDFILE || APR_HAS_MMAP)
 #error mod_file_cache only works on systems with APR_HAS_SENDFILE or APR_HAS_MMAP
 #endif

 #include "apr_mmap.h"
 #include "apr_strings.h"
 #include "apr_hash.h"
 #include "apr_buckets.h"

 #define APR_WANT_STRFUNC
 #include "apr_want.h"

 #if APR_HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif

 #include "httpd.h"
 #include "http_config.h"
 #include "http_log.h"
 #include "http_protocol.h"
 #include "http_request.h"
 #include "http_core.h"

 module AP_MODULE_DECLARE_DATA file_cache_module;

 typedef struct {
 #if APR_HAS_SENDFILE
     apr_file_t *file;
 #endif
     const char *filename;
     apr_finfo_t finfo;
     int is_mmapped;
 #if APR_HAS_MMAP
     apr_mmap_t *mm;
 #endif
     char mtimestr[APR_RFC822_DATE_LEN];
     char sizestr[21];   /* big enough to hold any 64-bit file size + null */
 } a_file;

 typedef struct {
     apr_hash_t *fileht;
 } a_server_config;


 static void *create_server_config(apr_pool_t *p, server_rec *s)
 {
     a_server_config *sconf = apr_palloc(p, sizeof(*sconf));

     sconf->fileht = apr_hash_make(p);
     return sconf;
 }

 static void cache_the_file(cmd_parms *cmd, const char *filename, int mmap)
 {
     a_server_config *sconf;
     a_file *new_file;
     a_file tmp;
     apr_file_t *fd = NULL;
     apr_status_t rc;
     const char *fspec;

     fspec = ap_server_root_relative(cmd->pool, filename);
     if (!fspec) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, APR_EBADPATH, cmd->server, APLOGNO(00794)
                      "invalid file path "
                      "%s, skipping", filename);
         return;
     }
     if ((rc = apr_stat(&tmp.finfo, fspec, APR_FINFO_MIN,
                                  cmd->temp_pool)) != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00795)
                      "unable to stat(%s), skipping", fspec);
         return;
     }
     if (tmp.finfo.filetype != APR_REG) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00796)
                      "%s isn't a regular file, skipping", fspec);
         return;
     }
     if (tmp.finfo.size > AP_MAX_SENDFILE) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00797)
                      "%s is too large to cache, skipping", fspec);
         return;
     }

     rc = apr_file_open(&fd, fspec, APR_READ | APR_BINARY | APR_XTHREAD,
                        APR_OS_DEFAULT, cmd->pool);
     if (rc != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00798)
                      "unable to open(%s, O_RDONLY), skipping", fspec);
         return;
     }
     apr_file_inherit_set(fd);

     /* WooHoo, we have a file to put in the cache */
     new_file = apr_pcalloc(cmd->pool, sizeof(a_file));
     new_file->finfo = tmp.finfo;

 #if APR_HAS_MMAP
     if (mmap) {
         /* MMAPFile directive. MMAP'ing the file
          * XXX: APR_HAS_LARGE_FILES issue; need to reject this request if
          * size is greater than MAX(apr_size_t) (perhaps greater than 1M?).
          */
         if ((rc = apr_mmap_create(&new_file->mm, fd, 0,
                                   (apr_size_t)new_file->finfo.size,
                                   APR_MMAP_READ, cmd->pool)) != APR_SUCCESS) {
             apr_file_close(fd);
             ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00799)
                          "unable to mmap %s, skipping", filename);
             return;
         }
         apr_file_close(fd);
         new_file->is_mmapped = TRUE;
     }
 #endif
 #if APR_HAS_SENDFILE
     if (!mmap) {
         /* CacheFile directive. Caching the file handle */
         new_file->is_mmapped = FALSE;
         new_file->file = fd;
     }
 #endif

     new_file->filename = fspec;
     apr_rfc822_date(new_file->mtimestr, new_file->finfo.mtime);
     apr_snprintf(new_file->sizestr, sizeof new_file->sizestr, "%" APR_OFF_T_FMT, new_file->finfo.size);

     sconf = ap_get_module_config(cmd->server->module_config, &file_cache_module);
     apr_hash_set(sconf->fileht, new_file->filename, strlen(new_file->filename), new_file);

 }

 static const char *cachefilehandle(cmd_parms *cmd, void *dummy, const char *filename)
 {
 #if APR_HAS_SENDFILE
     cache_the_file(cmd, filename, 0);
 #else
     /* Sendfile not supported by this OS */
     ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00800)
                  "unable to cache file: %s. Sendfile is not supported on this OS", filename);
 #endif
     return NULL;
 }
 static const char *cachefilemmap(cmd_parms *cmd, void *dummy, const char *filename)
 {
 #if APR_HAS_MMAP
     cache_the_file(cmd, filename, 1);
 #else
     /* MMAP not supported by this OS */
     ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00801)
                  "unable to cache file: %s. MMAP is not supported by this OS", filename);
 #endif
     return NULL;
 }

 static int file_cache_post_config(apr_pool_t *p, apr_pool_t *plog,
                                    apr_pool_t *ptemp, server_rec *s)
 {
     /* Hummm, anything to do here? */
     return OK;
 }

 /* If it's one of ours, fill in r->finfo now to avoid extra stat()... this is a
  * bit of a kludge, because we really want to run after core_translate runs.
  */
 static int file_cache_xlat(request_rec *r)
 {
     a_server_config *sconf;
     a_file *match;
     int res;

     sconf = ap_get_module_config(r->server->module_config, &file_cache_module);

     /* we only operate when at least one cachefile directive was used */
     if (!apr_hash_count(sconf->fileht)) {
         return DECLINED;
     }

     res = ap_core_translate(r);
     if (res != OK || !r->filename) {
         return res;
     }

     /* search the cache */
     match = (a_file *) apr_hash_get(sconf->fileht, r->filename, APR_HASH_KEY_STRING);
     if (match == NULL)
         return DECLINED;

     /* pass search results to handler */
     ap_set_module_config(r->request_config, &file_cache_module, match);

     /* shortcircuit the get_path_info() stat() calls and stuff */
     r->finfo = match->finfo;
     return OK;
 }

 static int mmap_handler(request_rec *r, a_file *file)
 {
 #if APR_HAS_MMAP
     conn_rec *c = r->connection;
     apr_bucket *b;
     apr_mmap_t *mm;
     apr_bucket_brigade *bb = apr_brigade_create(r->pool, c->bucket_alloc);

     apr_mmap_dup(&mm, file->mm, r->pool);
     b = apr_bucket_mmap_create(mm, 0, (apr_size_t)file->finfo.size,
                                c->bucket_alloc);
     APR_BRIGADE_INSERT_TAIL(bb, b);
     b = apr_bucket_eos_create(c->bucket_alloc);
     APR_BRIGADE_INSERT_TAIL(bb, b);

     if (ap_pass_brigade(r->output_filters, bb) != APR_SUCCESS)
         return AP_FILTER_ERROR;
 #endif
     return OK;
 }

 static int sendfile_handler(request_rec *r, a_file *file)
 {
 #if APR_HAS_SENDFILE
     conn_rec *c = r->connection;
     apr_bucket *b;
     apr_bucket_brigade *bb = apr_brigade_create(r->pool, c->bucket_alloc);

     apr_brigade_insert_file(bb, file->file, 0, file->finfo.size, r->pool);

     b = apr_bucket_eos_create(c->bucket_alloc);
     APR_BRIGADE_INSERT_TAIL(bb, b);

     if (ap_pass_brigade(r->output_filters, bb) != APR_SUCCESS)
         return AP_FILTER_ERROR;
 #endif
     return OK;
 }

 static int file_cache_handler(request_rec *r)
 {
     a_file *match;
     int errstatus;
     int rc = OK;

     /* Bail out if r->handler isn't the default value, and doesn't look like a Content-Type
      * XXX: Even though we made the user explicitly list each path to cache?
     */
     if (ap_strcmp_match(r->handler, "*/*") && !AP_IS_DEFAULT_HANDLER_NAME(r->handler)) {
         return DECLINED;
     }

     /* we don't handle anything but GET */
     if (r->method_number != M_GET) return DECLINED;

     /* did xlat phase find the file? */
     match = ap_get_module_config(r->request_config, &file_cache_module);

     if (match == NULL) {
         return DECLINED;
     }

     /* note that we would handle GET on this resource */
     r->allowed |= (AP_METHOD_BIT << M_GET);

     /* This handler has no use for a request body (yet), but we still
      * need to read and discard it if the client sent one.
      */
     if ((errstatus = ap_discard_request_body(r)) != OK)
         return errstatus;

     ap_update_mtime(r, match->finfo.mtime);

     /* ap_set_last_modified() always converts the file mtime to a string
      * which is slow.  Accelerate the common case.
      * ap_set_last_modified(r);
      */
     {
         apr_time_t mod_time;
         char *datestr;

         mod_time = ap_rationalize_mtime(r, r->mtime);
         if (mod_time == match->finfo.mtime)
             datestr = match->mtimestr;
         else {
             datestr = apr_palloc(r->pool, APR_RFC822_DATE_LEN);
             apr_rfc822_date(datestr, mod_time);
         }
         apr_table_setn(r->headers_out, "Last-Modified", datestr);
     }

     /* ap_set_content_length() always converts the same number and never
      * returns an error.  Accelerate it.
      */
     r->clength = match->finfo.size;
     apr_table_setn(r->headers_out, "Content-Length", match->sizestr);

     ap_set_etag(r);
     if ((errstatus = ap_meets_conditions(r)) != OK) {
        return errstatus;
     }

     /* Call appropriate handler */
     if (!r->header_only) {
         if (match->is_mmapped == TRUE)
             rc = mmap_handler(r, match);
         else
             rc = sendfile_handler(r, match);
     }

     return rc;
 }

 static command_rec file_cache_cmds[] =
 {
 AP_INIT_ITERATE("cachefile", cachefilehandle, NULL, RSRC_CONF,
      "A space separated list of files to add to the file handle cache at config time"),
 AP_INIT_ITERATE("mmapfile", cachefilemmap, NULL, RSRC_CONF,
      "A space separated list of files to mmap at config time"),
     {NULL}
 };

 static void register_hooks(apr_pool_t *p)
 {
     ap_hook_handler(file_cache_handler, NULL, NULL, APR_HOOK_LAST);
     ap_hook_post_config(file_cache_post_config, NULL, NULL, APR_HOOK_MIDDLE);
     ap_hook_translate_name(file_cache_xlat, NULL, NULL, APR_HOOK_MIDDLE);
     /* This trick doesn't work apparently because the translate hooks
        are single shot. If the core_hook returns OK, then our hook is
        not called.
     ap_hook_translate_name(file_cache_xlat, aszPre, NULL, APR_HOOK_MIDDLE);
     */

 }

 AP_DECLARE_MODULE(file_cache) =
 {
     STANDARD20_MODULE_STUFF,
     NULL,                     /* create per-directory config structure */
     NULL,                     /* merge per-directory config structures */
     create_server_config,     /* create per-server config structure */
     NULL,                     /* merge per-server config structures */
     file_cache_cmds,          /* command handlers */
     register_hooks            /* register hooks */
 };
	/* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	/*
	* Author: mod_file_cache by Bill Stoddard <stoddard apache.org>
	* Based on mod_mmap_static by Dean Gaudet <dgaudet arctic.org>
	*
	* v0.01: initial implementation
	*/

	/*
	Documentation:

	Some sites have a set of static files that are really busy, and
	change infrequently (or even on a regular schedule). Save time
	by caching open handles to these files. This module, unlike
	mod_mmap_static, caches open file handles, not file content.
	On systems (like Windows) with heavy system call overhead and
	that have an efficient sendfile implementation, caching file handles
	offers several advantages over caching content. First, the file system
	can manage the memory, allowing infrequently hit cached files to
	be paged out. Second, since caching open handles does not consume
	significant resources, it will be possible to enable an AutoLoadCache
	feature where static files are dynamically loaded in the cache
	as the server runs. On systems that have file change notification,
	this module can be enhanced to automatically garbage collect
	cached files that change on disk.

	This module should work on Unix systems that have sendfile. Place
	cachefile directives into your configuration to direct files to
	be cached.

	cachefile /path/to/file1
	cachefile /path/to/file2
	...

	These files are only cached when the server is restarted, so if you
	change the list, or if the files are changed, then you'll need to
	restart the server.

	To reiterate that point: if the files are modified in place
	without restarting the server you may end up serving requests that
	are completely bogus. You should update files by unlinking the old
	copy and putting a new copy in place.

	There's no such thing as inheriting these files across vhosts or
	whatever... place the directives in the main server only.

	Known problems:

	Don't use Alias or RewriteRule to move these files around... unless
	you feel like paying for an extra stat() on each request. This is
	a deficiency in the Apache API that will hopefully be solved some day.
	The file will be served out of the file handle cache, but there will be
	an extra stat() that's a waste.
	*/

	#include "apr.h"

	#if !(APR_HAS_SENDFILE \|\| APR_HAS_MMAP)
	#error mod_file_cache only works on systems with APR_HAS_SENDFILE or APR_HAS_MMAP
	#endif

	#include "apr_mmap.h"
	#include "apr_strings.h"
	#include "apr_hash.h"
	#include "apr_buckets.h"

	#define APR_WANT_STRFUNC
	#include "apr_want.h"

	#if APR_HAVE_SYS_TYPES_H
	#include <sys/types.h>
	#endif

	#include "httpd.h"
	#include "http_config.h"
	#include "http_log.h"
	#include "http_protocol.h"
	#include "http_request.h"
	#include "http_core.h"

	module AP_MODULE_DECLARE_DATA file_cache_module;

	typedef struct {
	#if APR_HAS_SENDFILE
	apr_file_t *file;
	#endif
	const char *filename;
	apr_finfo_t finfo;
	int is_mmapped;
	#if APR_HAS_MMAP
	apr_mmap_t *mm;
	#endif
	char mtimestr[APR_RFC822_DATE_LEN];
	char sizestr[21]; /* big enough to hold any 64-bit file size + null */
	} a_file;

	typedef struct {
	apr_hash_t *fileht;
	} a_server_config;


	static void create_server_config(apr_pool_t p, server_rec *s)
	{
	a_server_config sconf = apr_palloc(p, sizeof(sconf));

	sconf->fileht = apr_hash_make(p);
	return sconf;
	}

	static void cache_the_file(cmd_parms cmd, const char filename, int mmap)
	{
	a_server_config *sconf;
	a_file *new_file;
	a_file tmp;
	apr_file_t *fd = NULL;
	apr_status_t rc;
	const char *fspec;

	fspec = ap_server_root_relative(cmd->pool, filename);
	if (!fspec) {
	ap_log_error(APLOG_MARK, APLOG_WARNING, APR_EBADPATH, cmd->server, APLOGNO(00794)
	"invalid file path "
	"%s, skipping", filename);
	return;
	}
	if ((rc = apr_stat(&tmp.finfo, fspec, APR_FINFO_MIN,
	cmd->temp_pool)) != APR_SUCCESS) {
	ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00795)
	"unable to stat(%s), skipping", fspec);
	return;
	}
	if (tmp.finfo.filetype != APR_REG) {
	ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00796)
	"%s isn't a regular file, skipping", fspec);
	return;
	}
	if (tmp.finfo.size > AP_MAX_SENDFILE) {
	ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00797)
	"%s is too large to cache, skipping", fspec);
	return;
	}

	rc = apr_file_open(&fd, fspec, APR_READ \| APR_BINARY \| APR_XTHREAD,
	APR_OS_DEFAULT, cmd->pool);
	if (rc != APR_SUCCESS) {
	ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00798)
	"unable to open(%s, O_RDONLY), skipping", fspec);
	return;
	}
	apr_file_inherit_set(fd);

	/* WooHoo, we have a file to put in the cache */
	new_file = apr_pcalloc(cmd->pool, sizeof(a_file));
	new_file->finfo = tmp.finfo;

	#if APR_HAS_MMAP
	if (mmap) {
	/* MMAPFile directive. MMAP'ing the file
	* XXX: APR_HAS_LARGE_FILES issue; need to reject this request if
	* size is greater than MAX(apr_size_t) (perhaps greater than 1M?).
	*/
	if ((rc = apr_mmap_create(&new_file->mm, fd, 0,
	(apr_size_t)new_file->finfo.size,
	APR_MMAP_READ, cmd->pool)) != APR_SUCCESS) {
	apr_file_close(fd);
	ap_log_error(APLOG_MARK, APLOG_WARNING, rc, cmd->server, APLOGNO(00799)
	"unable to mmap %s, skipping", filename);
	return;
	}
	apr_file_close(fd);
	new_file->is_mmapped = TRUE;
	}
	#endif
	#if APR_HAS_SENDFILE
	if (!mmap) {
	/* CacheFile directive. Caching the file handle */
	new_file->is_mmapped = FALSE;
	new_file->file = fd;
	}
	#endif

	new_file->filename = fspec;
	apr_rfc822_date(new_file->mtimestr, new_file->finfo.mtime);
	apr_snprintf(new_file->sizestr, sizeof new_file->sizestr, "%" APR_OFF_T_FMT, new_file->finfo.size);

	sconf = ap_get_module_config(cmd->server->module_config, &file_cache_module);
	apr_hash_set(sconf->fileht, new_file->filename, strlen(new_file->filename), new_file);

	}

	static const char cachefilehandle(cmd_parms cmd, void dummy, const char filename)
	{
	#if APR_HAS_SENDFILE
	cache_the_file(cmd, filename, 0);
	#else
	/* Sendfile not supported by this OS */
	ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00800)
	"unable to cache file: %s. Sendfile is not supported on this OS", filename);
	#endif
	return NULL;
	}
	static const char cachefilemmap(cmd_parms cmd, void dummy, const char filename)
	{
	#if APR_HAS_MMAP
	cache_the_file(cmd, filename, 1);
	#else
	/* MMAP not supported by this OS */
	ap_log_error(APLOG_MARK, APLOG_WARNING, 0, cmd->server, APLOGNO(00801)
	"unable to cache file: %s. MMAP is not supported by this OS", filename);
	#endif
	return NULL;
	}

	static int file_cache_post_config(apr_pool_t p, apr_pool_t plog,
	apr_pool_t ptemp, server_rec s)
	{
	/* Hummm, anything to do here? */
	return OK;
	}

	/* If it's one of ours, fill in r->finfo now to avoid extra stat()... this is a
	* bit of a kludge, because we really want to run after core_translate runs.
	*/
	static int file_cache_xlat(request_rec *r)
	{
	a_server_config *sconf;
	a_file *match;
	int res;

	sconf = ap_get_module_config(r->server->module_config, &file_cache_module);

	/* we only operate when at least one cachefile directive was used */
	if (!apr_hash_count(sconf->fileht)) {
	return DECLINED;
	}

	res = ap_core_translate(r);
	if (res != OK \|\| !r->filename) {
	return res;
	}

	/* search the cache */
	match = (a_file *) apr_hash_get(sconf->fileht, r->filename, APR_HASH_KEY_STRING);
	if (match == NULL)
	return DECLINED;

	/* pass search results to handler */
	ap_set_module_config(r->request_config, &file_cache_module, match);

	/* shortcircuit the get_path_info() stat() calls and stuff */
	r->finfo = match->finfo;
	return OK;
	}

	static int mmap_handler(request_rec r, a_file file)
	{
	#if APR_HAS_MMAP
	conn_rec *c = r->connection;
	apr_bucket *b;
	apr_mmap_t *mm;
	apr_bucket_brigade *bb = apr_brigade_create(r->pool, c->bucket_alloc);

	apr_mmap_dup(&mm, file->mm, r->pool);
	b = apr_bucket_mmap_create(mm, 0, (apr_size_t)file->finfo.size,
	c->bucket_alloc);
	APR_BRIGADE_INSERT_TAIL(bb, b);
	b = apr_bucket_eos_create(c->bucket_alloc);
	APR_BRIGADE_INSERT_TAIL(bb, b);

	if (ap_pass_brigade(r->output_filters, bb) != APR_SUCCESS)
	return AP_FILTER_ERROR;
	#endif
	return OK;
	}

	static int sendfile_handler(request_rec r, a_file file)
	{
	#if APR_HAS_SENDFILE
	conn_rec *c = r->connection;
	apr_bucket *b;
	apr_bucket_brigade *bb = apr_brigade_create(r->pool, c->bucket_alloc);

	apr_brigade_insert_file(bb, file->file, 0, file->finfo.size, r->pool);

	b = apr_bucket_eos_create(c->bucket_alloc);
	APR_BRIGADE_INSERT_TAIL(bb, b);

	if (ap_pass_brigade(r->output_filters, bb) != APR_SUCCESS)
	return AP_FILTER_ERROR;
	#endif
	return OK;
	}

	static int file_cache_handler(request_rec *r)
	{
	a_file *match;
	int errstatus;
	int rc = OK;

	/* Bail out if r->handler isn't the default value, and doesn't look like a Content-Type
	* XXX: Even though we made the user explicitly list each path to cache?
	*/
	if (ap_strcmp_match(r->handler, "/") && !AP_IS_DEFAULT_HANDLER_NAME(r->handler)) {
	return DECLINED;
	}

	/* we don't handle anything but GET */
	if (r->method_number != M_GET) return DECLINED;

	/* did xlat phase find the file? */
	match = ap_get_module_config(r->request_config, &file_cache_module);

	if (match == NULL) {
	return DECLINED;
	}

	/* note that we would handle GET on this resource */
	r->allowed \|= (AP_METHOD_BIT << M_GET);

	/* This handler has no use for a request body (yet), but we still
	* need to read and discard it if the client sent one.
	*/
	if ((errstatus = ap_discard_request_body(r)) != OK)
	return errstatus;

	ap_update_mtime(r, match->finfo.mtime);

	/* ap_set_last_modified() always converts the file mtime to a string
	* which is slow. Accelerate the common case.
	* ap_set_last_modified(r);
	*/
	{
	apr_time_t mod_time;
	char *datestr;

	mod_time = ap_rationalize_mtime(r, r->mtime);
	if (mod_time == match->finfo.mtime)
	datestr = match->mtimestr;
	else {
	datestr = apr_palloc(r->pool, APR_RFC822_DATE_LEN);
	apr_rfc822_date(datestr, mod_time);
	}
	apr_table_setn(r->headers_out, "Last-Modified", datestr);
	}

	/* ap_set_content_length() always converts the same number and never
	* returns an error. Accelerate it.
	*/
	r->clength = match->finfo.size;
	apr_table_setn(r->headers_out, "Content-Length", match->sizestr);

	ap_set_etag(r);
	if ((errstatus = ap_meets_conditions(r)) != OK) {
	return errstatus;
	}

	/* Call appropriate handler */
	if (!r->header_only) {
	if (match->is_mmapped == TRUE)
	rc = mmap_handler(r, match);
	else
	rc = sendfile_handler(r, match);
	}

	return rc;
	}

	static command_rec file_cache_cmds[] =
	{
	AP_INIT_ITERATE("cachefile", cachefilehandle, NULL, RSRC_CONF,
	"A space separated list of files to add to the file handle cache at config time"),
	AP_INIT_ITERATE("mmapfile", cachefilemmap, NULL, RSRC_CONF,
	"A space separated list of files to mmap at config time"),
	{NULL}
	};

	static void register_hooks(apr_pool_t *p)
	{
	ap_hook_handler(file_cache_handler, NULL, NULL, APR_HOOK_LAST);
	ap_hook_post_config(file_cache_post_config, NULL, NULL, APR_HOOK_MIDDLE);
	ap_hook_translate_name(file_cache_xlat, NULL, NULL, APR_HOOK_MIDDLE);
	/* This trick doesn't work apparently because the translate hooks
	are single shot. If the core_hook returns OK, then our hook is
	not called.
	ap_hook_translate_name(file_cache_xlat, aszPre, NULL, APR_HOOK_MIDDLE);
	*/

	}

	AP_DECLARE_MODULE(file_cache) =
	{
	STANDARD20_MODULE_STUFF,
	NULL, /* create per-directory config structure */
	NULL, /* merge per-directory config structures */
	create_server_config, /* create per-server config structure */
	NULL, /* merge per-server config structures */
	file_cache_cmds, /* command handlers */
	register_hooks /* register hooks */
	};