source3/lib/module.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    module loading system
   4
   5    Copyright (C) Jelmer Vernooij 2002-2003
   6    Copyright (C) Stefan (metze) Metzmacher 2003
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23
  24 /* Load a dynamic module.  Only log a level 0 error if we are not checking
  25    for the existence of a module (probling). */
  26
  27 static NTSTATUS do_smb_load_module(const char *module_name, bool is_probe)
  28 {
  29         void *handle;
  30         init_module_function *init;
  31         NTSTATUS status;
  32         const char *error;
  33
  34         /* Always try to use LAZY symbol resolving; if the plugin has
  35          * backwards compatibility, there might be symbols in the
  36          * plugin referencing to old (removed) functions
  37          */
  38         handle = dlopen(module_name, RTLD_LAZY);
  39
  40         /* This call should reset any possible non-fatal errors that
  41            occured since last call to dl* functions */
  42         error = dlerror();
  43
  44         if(!handle) {
  45                 int level = is_probe ? 3 : 0;
  46                 DEBUG(level, ("Error loading module '%s': %s\n", module_name, error ? error : ""));
  47                 return NT_STATUS_UNSUCCESSFUL;
  48         }
  49
  50         init = (init_module_function *)dlsym(handle, "init_samba_module");
  51
  52         /* we must check dlerror() to determine if it worked, because
  53            dlsym() can validly return NULL */
  54         error = dlerror();
  55         if (error) {
  56                 DEBUG(0, ("Error trying to resolve symbol 'init_samba_module' "
  57                           "in %s: %s\n", module_name, error));
  58                 dlclose(handle);
  59                 return NT_STATUS_UNSUCCESSFUL;
  60         }
  61
  62         DEBUG(2, ("Module '%s' loaded\n", module_name));
  63
  64         status = init();
  65         if (!NT_STATUS_IS_OK(status)) {
  66                 DEBUG(0, ("Module '%s' initialization failed: %s\n",
  67                             module_name, get_friendly_nt_error_msg(status)));
  68                 dlclose(handle);
  69         }
  70
  71         return status;
  72 }
  73
  74 NTSTATUS smb_load_module(const char *module_name)
  75 {
  76         return do_smb_load_module(module_name, False);
  77 }
  78
  79 /* Load all modules in list and return number of
  80  * modules that has been successfully loaded */
  81 int smb_load_modules(const char **modules)
  82 {
  83         int i;
  84         int success = 0;
  85
  86         for(i = 0; modules[i]; i++){
  87                 if(NT_STATUS_IS_OK(smb_load_module(modules[i]))) {
  88                         success++;
  89                 }
  90         }
  91
  92         DEBUG(2, ("%d modules successfully loaded\n", success));
  93
  94         return success;
  95 }
  96
  97 NTSTATUS smb_probe_module(const char *subsystem, const char *module)
  98 {
  99         char *full_path = NULL;
 100         TALLOC_CTX *ctx = talloc_stackframe();
 101         NTSTATUS status;
 102
 103         /* Check for absolute path */
 104
 105         /* if we make any 'samba multibyte string'
 106            calls here, we break
 107            for loading string modules */
 108
 109         DEBUG(5, ("Probing module '%s'\n", module));
 110
 111         if (module[0] == '/') {
 112                 status = do_smb_load_module(module, True);
 113                 TALLOC_FREE(ctx);
 114                 return status;
 115         }
 116
 117         full_path = talloc_asprintf(ctx,
 118                                     "%s/%s.%s",
 119                                     modules_path(ctx, subsystem),
 120                                     module,
 121                                     shlib_ext());
 122         if (!full_path) {
 123                 TALLOC_FREE(ctx);
 124                 return NT_STATUS_NO_MEMORY;
 125         }
 126
 127         DEBUG(5, ("Probing module '%s': Trying to load from %s\n",
 128                 module, full_path));
 129
 130         status = do_smb_load_module(full_path, True);
 131
 132         TALLOC_FREE(ctx);
 133         return status;
 134 }
 135
 136 void init_modules(void)
 137 {
 138         /* FIXME: This can cause undefined symbol errors :
 139          *  smb_register_vfs() isn't available in nmbd, for example */
 140         if(lp_preload_modules())
 141                 smb_load_modules(lp_preload_modules());
 142 }