The following reply was made to PR mod_dld/540; it has been noted by GNATS.
From: [EMAIL PROTECTED] (Rodent of Unusual Size)
To: [EMAIL PROTECTED], [EMAIL PROTECTED], [EMAIL PROTECTED]
Subject: Re: mod_dld/540: mod_dld corrupts module count
Date: Sun, 04 May 1997 09:00:22 -0400
[Additional information, also from mail]
From the fingers of Johannes Deisenhofer flowed the following:
>
>I have done some more research. I have built and tested a patch
>that should fix my problem and the problem with mod_dld.
>The patch is included.
>
>Justifikation for the changes:
>1.) interpreting total_modules as the numer of *statically* linked
> modules makes changes to total_modules unnecessary.
>2.) But then, we have to allocate extra space, which was
> only partly done.
>3.) Removing the check around module numbering ensures that
> num_modules is increased. (Which did not happen before since
> the index was already set in setup_prelinked_modules)
>
>Furthermore, I have included my mod_dynamic module, replacing
>mod_dld for COFF and ELF systems. It requires this patch to work.
>
>Please give me a short note if this module has any chance of being in
>the distribution, since I'll otherwise make it availible by myself.
>
>Keep up the good work!
>--
>// Johannes Deisenhofer [EMAIL PROTECTED]
>
>--------------167E2781446B
>Content-Type: TEXT/PLAIN; CHARSET=us-ascii; NAME="http_config.diff"
>Content-ID: <[EMAIL PROTECTED]>
>Content-Description:
>
>*** http_config.c Sun Jan 26 02:15:11 1997
>--- /mvwg/hb13/src/subsys/apache_1.2/http_config.c Sat Mar 15 20:21:00 1997
>***************
>*** 86,90 ****
> /* num_modules is the number of currently active modules. */
> static int num_modules = 0;
>! /* total_modules is the number of modules linked in. */
> static int total_modules = 0;
> module *top_module = NULL;
>--- 86,90 ----
> /* num_modules is the number of currently active modules. */
> static int num_modules = 0;
>! /* total_modules is the number of modules statically linked in. */
> static int total_modules = 0;
> module *top_module = NULL;
>***************
>*** 123,127 ****
> create_empty_config (pool *p)
> {
>! void **conf_vector = (void **)pcalloc(p, sizeof(void*) * total_modules);
> return (void *)conf_vector;
> }
>--- 123,127 ----
> create_empty_config (pool *p)
> {
>! void **conf_vector = (void **)pcalloc(p, sizeof(void*) *
>(total_modules+DYNAMIC_MODULE_LIMIT));
> return (void *)conf_vector;
> }
>***************
>*** 145,149 ****
> merge_per_dir_configs (pool *p, void *base, void *new)
> {
>! void **conf_vector = (void **)pcalloc(p, sizeof(void*) * total_modules);
> void **base_vector = (void **) base;
> void **new_vector = (void **) new;
>--- 145,149 ----
> merge_per_dir_configs (pool *p, void *base, void *new)
> {
>! void **conf_vector = (void **)pcalloc(p, sizeof(void*) *
>(total_modules+DYNAMIC_MODULE_LIMIT));
> void **base_vector = (void **) base;
> void **new_vector = (void **) new;
>***************
>*** 383,389 ****
> top_module = m;
> }
>- if (m->module_index == -1) {
> m->module_index = num_modules++;
>- }
> }
>
>--- 383,387 ----
>
>--------------167E2781446B
>Content-Type: TEXT/PLAIN; CHARSET=us-ascii; NAME="mod_dynamic.c"
>Content-ID: <[EMAIL PROTECTED]>
>Content-Description:
>
>/* ====================================================================
> * Copyright (c) 1995-1997 The Apache Group. All rights reserved.
> *
> * Redistribution and use in source and binary forms, with or without
> * modification, are permitted provided that the following conditions
> * are met:
> *
> * 1. Redistributions of source code must retain the above copyright
> * notice, this list of conditions and the following disclaimer.
> *
> * 2. Redistributions in binary form must reproduce the above copyright
> * notice, this list of conditions and the following disclaimer in
> * the documentation and/or other materials provided with the
> * distribution.
> *
> * 3. All advertising materials mentioning features or use of this
> * software must display the following acknowledgment:
> * "This product includes software developed by the Apache Group
> * for use in the Apache HTTP server project (http://www.apache.org/)."
> *
> * 4. The names "Apache Server" and "Apache Group" must not be used to
> * endorse or promote products derived from this software without
> * prior written permission.
> *
> * 5. Redistributions of any form whatsoever must retain the following
> * acknowledgment:
> * "This product includes software developed by the Apache Group
> * for use in the Apache HTTP server project (http://www.apache.org/)."
> *
> * THIS SOFTWARE IS PROVIDED BY THE APACHE GROUP ``AS IS'' AND ANY
> * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
> * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE APACHE GROUP OR
> * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
> * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
> * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
> * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
> * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
> * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
> * OF THE POSSIBILITY OF SUCH DAMAGE.
> * ====================================================================
> *
> * This software consists of voluntary contributions made by many
> * individuals on behalf of the Apache Group and was originally based
> * on public domain software written at the National Center for
> * Supercomputing Applications, University of Illinois, Urbana-Champaign.
> * For more information on the Apache Group and the Apache HTTP server
> * project, please see <http://www.apache.org/>.
> *
> */
>
>#include "httpd.h"
>#include "http_config.h"
>
>#include <dlfcn.h>
>
>static int loading_done = 0; /* Loaded the modules yet? */
>
>static const char *
>load_module (cmd_parms *cmd, void *dummy, char *modname, char *filename)
>{
> module *modp;
> void *dlhandle;
>
> if (loading_done) return NULL;
> if (strstr(filename,"/"))
> filename = server_root_relative(cmd->pool,filename);
> dlhandle = dlopen(filename,RTLD_NOW);
> if (dlhandle==NULL) {
> return pstrcat (cmd->pool, "Cannot load '", filename,
> "' as a module\n", dlerror(), NULL);
> }
> if (!(modp = (module *)dlsym (dlhandle,modname))) {
> return pstrcat (cmd->pool, "Can't find symbol ", modname,
> " in file ", filename, "\n",
> dlerror(), NULL);
> }
>
> add_module (modp);
>
> /* Alethea Patch (rws,djw2) - need to run configuration functions
> in new modules */
>
> if (modp->create_server_config)
> ((void**)cmd->server->module_config)[modp->module_index]=
> (*modp->create_server_config)(cmd->pool, cmd->server);
>
> if (modp->create_dir_config)
> ((void**)cmd->server->lookup_defaults)[modp->module_index]=
> (*modp->create_dir_config)(cmd->pool, NULL);
>
> return NULL;
>}
>
>static const char
>*load_file (cmd_parms *cmd, void *dummy, char *filename)
>{
> char *errname;
> void *dlhandle;
>
> if (loading_done) return NULL;
> if (strstr(filename,"/"))
> filename = server_root_relative(cmd->pool,filename);
> dlhandle = dlopen(filename,RTLD_NOW);
> if (dlhandle==NULL) {
> return pstrcat (cmd->pool, "Cannot load '", filename,
> "' as a module\n", dlerror(), NULL);
> }
>
> return NULL;
>}
>
>static void
>dld_init (server_rec *dummy, pool *p)
>{
> loading_done = 1;
>}
>
>static command_rec
>dld_cmds[] = {
>{ "LoadModule", load_module, NULL, RSRC_CONF, TAKE2,
> "a module name, and the name of a file to load it from"},
>{ "LoadFile", load_file, NULL, RSRC_CONF, ITERATE,
> "files or libraries to link into the server at runtime"},
>{ NULL }
>};
>
>module dynamic_module = {
> STANDARD_MODULE_STUFF,
> dld_init, /* initializer */
> NULL, /* create per-dir config */
> NULL, /* merge per-dir config */
> NULL, /* server config */
> NULL, /* merge server config */
> dld_cmds, /* command table */
> NULL, /* handlers */
> NULL, /* filename translation */
> NULL, /* check_user_id */
> NULL, /* check auth */
> NULL, /* check access */
> NULL, /* type_checker */
> NULL /* logger */
>};
>
>--------------167E2781446B
>Content-Type: TEXT/PLAIN; CHARSET=us-ascii; NAME="mod_dynamic.txt"
>Content-ID: <[EMAIL PROTECTED]>
>Content-Description:
>
>mod_dynamic:
>
>Load Apache modules at runtime.
>
>This is beta code!
>
>This module makes it possible to put modules into shared libraries, that
>can be loaded at runtime. You no longer have to recompile apache to
>customize it.
>This code is based on the apache module mod_dld. It uses native calls and
>does not require GNU dld, which does not work for most current systems.
>This should work for all systems using an ELF or COFF executable format.
>
>Advantages:
> - You don't have to recompile apache if you want to add or try a new
> module
> - Nice for precompiled binaries and commercial add-ons.
>
>Disadvantages:
> - Only works for systems having dlopen/dlsym calls. (This at least
> includes
> SUN-OS, Solaris, IRIX, Linux and FreeBSD: check your man pages)
> - Minor speed decrease (shouldn't be noticable)
> - Requires some fiddling with compiler/linker options when compiling
>
>* WARNING *
>Dynamic Modules are, for now, not supported by apache's configuration
>mechanism. Therefore, you have to know your way around in a Makefile, and
>know the necessary compiler and linker options for building shared libraries
>on your system.
>This can be tricky. Ever heard of PIC and symbol tables? Good.
>
>Compiling Apache:
>Configure Apache just to include the preconfigured modules, and this module.
>Do not configure modules that you want to add dynamically.
>
>For some systems, you have to add a linker option to keep your
>symbols in the executable. For linux/gcc, this is '-export-dynamic'
>
>Compiling modules:
>You have to compile your modules into a shared libary. Details should be in
>your manuals.
>Try something like cc -shared -o module.so module.c
>
>Runtime Configuration:
>Put your modules somewhere below server root.
>For every module, add something like
>
>LoadModule my_module modules/mod_mymod.so
>
>to http.conf. This has to appear *before* any configuration item for
>dynamically loaded modules. Otherwise, you will get a syntax error.
>
>modules/mod_mymod.so is the relative or absolute path to the
>module's shared_library.
>
>my_module is the name of the module's function table.
>Find 'STANDARD_MODULE_STUFF' in the module's source code, and take
>the symbol one line above, after 'module'.
>Why is that required? Because its compatible with mod_dld, and doesn't
>require any changes to existing modules.
>
>Example: Configure all of apache 1.2b7's standard modules dynamically
>
>LoadModule headers_module modules/mod_headers.so
>LoadModule rewrite_module modules/mod_rewrite.so
>LoadModule status_module modules/mod_status.so
>LoadModule info_module modules/mod_info.so
>LoadModule usertrack_module modules/mod_usertrack.so
>LoadModule digest_module modules/mod_digest.so
>LoadModule expires_module modules/mod_expires.so
>LoadModule agent_log_module modules/mod_log_agent.so
>LoadModule referer_log_module modules/mod_log_referer.so
>LoadModule proxy_module modules/mod_proxy.so
>
>CookieExpires "2 weeks"
> ... more of module configuration
>
>If you just give the modules name without any path,
>LD_LIBRARY_PATH is searched for the module.
>
>Apache will not reload or add modules after a SIGHUP to the
>running process. This would require to unload modules, and there is
>currently no way to do it.
>
>There is also an Configuration option 'LoadFile somelibrary.so'.
>It will link the named library in. Didn't ever need it.
>
>Have Fun
>Johannes Deisenhofer
>[EMAIL PROTECTED], [EMAIL PROTECTED]
>
>--------------167E2781446B--
