/* 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.
*/
/* * This module is used to load Apache modules at runtime. This means that the * server functionality can be extended without recompiling and even without * taking the server down at all. Only a HUP or AP_SIG_GRACEFUL signal * needs to be sent to the server to reload the dynamically loaded modules. * * To use, you'll first need to build your module as a shared library, then * update your configuration (httpd.conf) to get the Apache core to load the * module at start-up. * * The easiest way to build a module as a shared library is to use the * `SharedModule' command in the Configuration file, instead of `AddModule'. * You should also change the file extension from `.o' to `.so'. So, for * example, to build the status module as a shared library edit Configuration * and change * AddModule modules/standard/mod_status.o * to * SharedModule modules/standard/mod_status.so * * Run Configure and make. Now Apache's httpd binary will _not_ include * mod_status. Instead a shared object called mod_status.so will be build, in * the modules/standard directory. You can build most of the modules as shared * libraries like this. * * To use the shared module, move the .so file(s) into an appropriate * directory. You might like to create a directory called "modules" under you * server root for this (e.g. /usr/local/httpd/modules). * * Then edit your conf/httpd.conf file, and add LoadModule lines. For * example * LoadModule status_module modules/mod_status.so * * The first argument is the module's structure name (look at the end of the * module source to find this). The second option is the path to the module * file, relative to the server root. Put these directives right at the top * of your httpd.conf file. * * Now you can start Apache. A message will be logged at "debug" level to your * error_log to confirm that the module(s) are loaded (use "LogLevel debug" * directive to get these log messages). * * If you edit the LoadModule directives while the server is live you can get * Apache to re-load the modules by sending it a HUP or AP_SIG_GRACEFUL * signal as normal. You can use this to dynamically change the capability * of your server without bringing it down. * * Because currently there is only limited builtin support in the Configure * script for creating the shared library files (`.so'), please consult your * vendors cc(1), ld(1) and dlopen(3) manpages to find out the appropriate * compiler and linker flags and insert them manually into the Configuration * file under CFLAGS_SHLIB, LDFLAGS_SHLIB and LDFLAGS_SHLIB_EXPORT. * * If you still have problems figuring out the flags both try the paper * http://developer.netscape.com/library/documentation/enterprise * /unix/svrplug.htm#1013807 * or install a Perl 5 interpreter on your platform and then run the command * * $ perl -V:usedl -V:ccdlflags -V:cccdlflags -V:lddlflags * * This gives you what type of dynamic loading Perl 5 uses on your platform * and which compiler and linker flags Perl 5 uses to create the shared object * files. * * Another location where you can find useful hints is the `ltconfig' script * of the GNU libtool 1.2 package. Search for your platform name inside the * various "case" constructs. *
*/
/* we need to setup this value for dummy to make sure that we don't try * to add a non-existent tree into the build when we return to * execute_now.
*/
*(ap_directive_t **)dummy = NULL;
/* * check for already existing module * If it already exists, we have nothing to do * Check both dynamically-loaded modules and statically-linked modules.
*/
sconf = (so_server_conf *)ap_get_module_config(cmd->server->module_config,
&so_module);
modie = (ap_module_symbol_t *)sconf->loaded_modules->elts; for (i = 0; i < sconf->loaded_modules->nelts; i++) {
modi = &modie[i]; if (modi->name != NULL && strcmp(modi->name, modname) == 0) {
ap_log_perror(APLOG_MARK, APLOG_WARNING, 0, cmd->pool, APLOGNO(01574) "module %s is already loaded, skipping",
modname); return NULL;
}
}
for (i = 0; ap_preloaded_modules[i]; i++) { constchar *preload_name;
apr_size_t preload_len;
apr_size_t thismod_len;
modp = ap_preloaded_modules[i];
/* make sure we're comparing apples with apples * make sure name of preloaded module is mod_FOO.c * make sure name of structure being loaded is FOO_module
*/
/* * Load the file into the Apache address space
*/
error = dso_load(cmd, &modhandle, filename, &module_file); if (error) return error;
ap_log_perror(APLOG_MARK, APLOG_DEBUG, 0, cmd->pool, APLOGNO(01575) "loaded module %s from %s", modname, module_file);
/* * Retrieve the pointer to the module structure through the module name: * First with the hidden variant (prefix `AP_') and then with the plain * symbol name.
*/ if (apr_dso_sym(&modsym, modhandle, modname) != APR_SUCCESS) { char my_error[256];
/* * Make sure the found module structure is really a module structure *
*/ if (modp->magic != MODULE_MAGIC_COOKIE) { return apr_psprintf(cmd->pool, "API module structure '%s' in file %s " "is garbled - expected signature %08lx but saw " "%08lx - perhaps this is not an Apache module DSO, " "or was compiled for a different Apache version?",
modname, module_file,
MODULE_MAGIC_COOKIE, modp->magic);
}
/* * Add this module to the Apache core structures
*/
error = ap_add_loaded_module(modp, cmd->pool, modname); if (error) { return error;
}
/* * Register a cleanup in the config apr_pool_t (normally pconf). When * we do a restart (or shutdown) this cleanup will cause the * shared object to be unloaded.
*/
apr_pool_cleanup_register(cmd->pool, modi, unload_module, apr_pool_cleanup_null);
/* * Finally we need to run the configuration process for the module
*/
ap_single_module_configure(cmd->pool, cmd->server, modp);
return NULL;
}
/* * This implements the LoadFile directive and loads an arbitrary * shared object file into the address space of the server process.
*/
staticconst command_rec so_cmds[] = {
AP_INIT_TAKE2("LoadModule", load_module, NULL, RSRC_CONF | EXEC_ON_READ, "a module name and the name of a shared object file to load it from"),
AP_INIT_ITERATE("LoadFile", load_file, NULL, RSRC_CONF | EXEC_ON_READ, "shared object file or library to load into the server at runtime"),
{ NULL }
};
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