source/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 #ifdef HAVE_DLOPEN
  25
  26 /* Load a dynamic module.  Only log a level 0 error if we are not checking
  27    for the existence of a module (probling). */
  28
  29 static NTSTATUS do_smb_load_module(const char *module_name, BOOL is_probe)
  30 {
  31         void *handle;
  32         init_module_function *init;
  33         NTSTATUS status;
  34         const char *error;
  35
  36         /* Always try to use LAZY symbol resolving; if the plugin has
  37          * backwards compatibility, there might be symbols in the
  38          * plugin referencing to old (removed) functions
  39          */
  40         handle = sys_dlopen(module_name, RTLD_LAZY);
  41
  42         /* This call should reset any possible non-fatal errors that
  43            occured since last call to dl* functions */
  44         error = sys_dlerror();
  45
  46         if(!handle) {
  47                 int level = is_probe ? 3 : 0;
  48                 DEBUG(level, ("Error loading module '%s': %s\n", module_name, error ? error : ""));
  49                 return NT_STATUS_UNSUCCESSFUL;
  50         }
  51
  52         init = (init_module_function *)sys_dlsym(handle, "init_module");
  53
  54         /* we must check sys_dlerror() to determine if it worked, because
  55            sys_dlsym() can validly return NULL */
  56         error = sys_dlerror();
  57         if (error) {
  58                 DEBUG(0, ("Error trying to resolve symbol 'init_module' in %s: %s\n",
  59                           module_name, error));
  60                 return NT_STATUS_UNSUCCESSFUL;
  61         }
  62
  63         DEBUG(2, ("Module '%s' loaded\n", module_name));
  64
  65         status = init();
  66         if (!NT_STATUS_IS_OK(status)) {
  67                 DEBUG(0, ("Module '%s' initialization failed: %s\n",
  68                             module_name, get_friendly_nt_error_msg(status)));
  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                         lib_path(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 #else /* HAVE_DLOPEN */
 137
 138 NTSTATUS smb_load_module(const char *module_name)
 139 {
 140         DEBUG(0,("This samba executable has not been built with plugin support\n"));
 141         return NT_STATUS_NOT_SUPPORTED;
 142 }
 143
 144 int smb_load_modules(const char **modules)
 145 {
 146         DEBUG(0,("This samba executable has not been built with plugin support\n"));
 147         return -1;
 148 }
 149
 150 NTSTATUS smb_probe_module(const char *subsystem, const char *module)
 151 {
 152         DEBUG(0,("This samba executable has not been built with plugin support, not probing\n"));
 153         return NT_STATUS_NOT_SUPPORTED;
 154 }
 155
 156 #endif /* HAVE_DLOPEN */
 157
 158 void init_modules(void)
 159 {
 160         /* FIXME: This can cause undefined symbol errors :
 161          *  smb_register_vfs() isn't available in nmbd, for example */
 162         if(lp_preload_modules())
 163                 smb_load_modules(lp_preload_modules());
 164 }