source: branches/samba-3.3.x/source/lib/module.c

/* 
   Unix SMB/CIFS implementation.
   module loading system

   Copyright (C) Jelmer Vernooij 2002-2003
   Copyright (C) Stefan (metze) Metzmacher 2003
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

#ifdef HAVE_DLOPEN

/* Load a dynamic module.  Only log a level 0 error if we are not checking 
   for the existence of a module (probling). */

static NTSTATUS do_smb_load_module(const char *module_name, bool is_probe)
{
        void *handle;
        init_module_function *init;
        NTSTATUS status;
        const char *error;

        /* Always try to use LAZY symbol resolving; if the plugin has 
         * backwards compatibility, there might be symbols in the 
         * plugin referencing to old (removed) functions
         */
        handle = sys_dlopen(module_name, RTLD_LAZY);

        /* This call should reset any possible non-fatal errors that 
           occured since last call to dl* functions */
        error = sys_dlerror();

        if(!handle) {
                int level = is_probe ? 3 : 0;
                DEBUG(level, ("Error loading module '%s': %s\n", module_name, error ? error : ""));
                return NT_STATUS_UNSUCCESSFUL;
        }

        init = (init_module_function *)sys_dlsym(handle, "init_samba_module");

        /* we must check sys_dlerror() to determine if it worked, because
           sys_dlsym() can validly return NULL */
        error = sys_dlerror();
        if (error) {
                DEBUG(0, ("Error trying to resolve symbol 'init_samba_module' "
                          "in %s: %s\n", module_name, error));
                sys_dlclose(handle);
                return NT_STATUS_UNSUCCESSFUL;
        }

        DEBUG(2, ("Module '%s' loaded\n", module_name));

        status = init();
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(0, ("Module '%s' initialization failed: %s\n",
                            module_name, get_friendly_nt_error_msg(status)));
                sys_dlclose(handle);
        }

        return status;
}

NTSTATUS smb_load_module(const char *module_name)
{
        return do_smb_load_module(module_name, False);
}

/* Load all modules in list and return number of
 * modules that has been successfully loaded */
int smb_load_modules(const char **modules)
{
        int i;
        int success = 0;

        for(i = 0; modules[i]; i++){
                if(NT_STATUS_IS_OK(smb_load_module(modules[i]))) {
                        success++;
                }
        }

        DEBUG(2, ("%d modules successfully loaded\n", success));

        return success;
}

NTSTATUS smb_probe_module(const char *subsystem, const char *module)
{
        char *full_path = NULL;
        TALLOC_CTX *ctx = talloc_stackframe();
        NTSTATUS status;

        /* Check for absolute path */

        /* if we make any 'samba multibyte string'
           calls here, we break
           for loading string modules */

        DEBUG(5, ("Probing module '%s'\n", module));

        if (module[0] == '/') {
                status = do_smb_load_module(module, True);
                TALLOC_FREE(ctx);
                return status;
        }

        full_path = talloc_asprintf(ctx,
                        "%s/%s.%s",
                        modules_path(subsystem),
                        module,
                        shlib_ext());
        if (!full_path) {
                TALLOC_FREE(ctx);
                return NT_STATUS_NO_MEMORY;
        }

        DEBUG(5, ("Probing module '%s': Trying to load from %s\n",
                module, full_path));

        status = do_smb_load_module(full_path, True);

        TALLOC_FREE(ctx);
        return status;
}

#else /* HAVE_DLOPEN */

NTSTATUS smb_load_module(const char *module_name)
{
        DEBUG(0,("This samba executable has not been built with plugin support\n"));
        return NT_STATUS_NOT_SUPPORTED;
}

int smb_load_modules(const char **modules)
{
        DEBUG(0,("This samba executable has not been built with plugin support\n"));
        return -1;
}

NTSTATUS smb_probe_module(const char *subsystem, const char *module)
{
        DEBUG(0,("This samba executable has not been built with plugin support, not probing\n")); 
        return NT_STATUS_NOT_SUPPORTED;
}

#endif /* HAVE_DLOPEN */

void init_modules(void)
{
        /* FIXME: This can cause undefined symbol errors :
         *  smb_register_vfs() isn't available in nmbd, for example */
        if(lp_preload_modules()) 
                smb_load_modules(lp_preload_modules());
}