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Celestin Apprentice 4
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Apache 1.0
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mod_dld.c
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1995-12-04
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/* ====================================================================
* Copyright (c) 1995 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
* IT'S 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/>.
*
*/
/*
* A first stab at dynamic loading, using the GNU dld library
* (or at least, an embarassingly old version of it...).
*/
#include "httpd.h"
#include "http_config.h"
#include "http_conf_globals.h" /* server_argv0. Sigh... */
#include <dld.h>
/*
* The hard part of implementing LoadModule is deciding what to do about
* rereading the config files. This proof-of-concept implementation takes the
* cheap way out: we only actually load the modules the first time through.
*/
static int been_there_done_that = 0; /* Loaded the modules yet? */
static int have_symbol_table = 0;
char *insure_dld_sane()
{
int errcode;
char *bin_name;
if (have_symbol_table) return NULL;
bin_name = dld_find_executable (server_argv0);
if ((errcode = dld_init (bin_name))) {
dld_perror (server_argv0);
return "Cannot find server binary (needed for dynamic linking).";
}
have_symbol_table = 1;
return NULL;
}
char *link_file (pool *p, char *filename)
{
int errcode;
filename = server_root_relative (p, filename);
if ((errcode = dld_link (filename))) {
dld_perror (server_argv0);
return pstrcat (p, "Cannot load ", filename, " into server", NULL);
}
return NULL;
}
char *load_module (cmd_parms *cmd, void *dummy, char *modname, char *filename)
{
char *errname;
module *modp;
if (been_there_done_that) return NULL;
if ((errname = insure_dld_sane())) return errname;
if ((errname = link_file (cmd->pool, filename))) return errname;
if (!(modp = (module *)dld_get_symbol (modname))) {
return pstrcat (cmd->pool, "Can't find module ", modname,
" in file ", filename, 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;
}
char *load_file (cmd_parms *cmd, void *dummy, char *filename)
{
char *errname;
if (been_there_done_that) return NULL;
if ((errname = insure_dld_sane())) return errname;
if ((errname = link_file (cmd->pool, filename))) return errname;
return NULL;
}
void check_loaded_modules (server_rec *dummy, pool *p)
{
if (been_there_done_that) return;
if (dld_undefined_sym_count > 0) {
/* Screwup. Do the best we can to inform the user, and exit */
char **bad_syms = dld_list_undefined_sym();
int i;
fprintf(stderr, "Dynamic linking error --- symbols left undefined.\n");
fprintf(stderr, "(It may help to relink libraries).\n");
fprintf(stderr, "Undefined symbols follow:\n");
for (i = 0; i < dld_undefined_sym_count; ++i)
fprintf (stderr, "%s\n", bad_syms[i]);
exit (1);
}
been_there_done_that = 1;
}
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 dld_module = {
STANDARD_MODULE_STUFF,
check_loaded_modules, /* 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 */
};