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_samba_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_samba_module' "
  59                           "in %s: %s\n", module_name, error));
  60                 sys_dlclose(handle);
  61                 return NT_STATUS_UNSUCCESSFUL;
  62         }
  63
  64         DEBUG(2, ("Module '%s' loaded\n", module_name));
  65
  66         status = init();
  67         if (!NT_STATUS_IS_OK(status)) {
  68                 DEBUG(0, ("Module '%s' initialization failed: %s\n",
  69                             module_name, get_friendly_nt_error_msg(status)));
  70                 sys_dlclose(handle);
  71         }
  72
  73         return status;
  74 }
  75
  76 NTSTATUS smb_load_module(const char *module_name)
  77 {
  78         return do_smb_load_module(module_name, False);
  79 }
  80
  81 /* Load all modules in list and return number of
  82  * modules that has been successfully loaded */
  83 int smb_load_modules(const char **modules)
  84 {
  85         int i;
  86         int success = 0;
  87
  88         for(i = 0; modules[i]; i++){
  89                 if(NT_STATUS_IS_OK(smb_load_module(modules[i]))) {
  90                         success++;
  91                 }
  92         }
  93
  94         DEBUG(2, ("%d modules successfully loaded\n", success));
  95
  96         return success;
  97 }
  98
  99 NTSTATUS smb_probe_module(const char *subsystem, const char *module)
 100 {
 101         char *full_path = NULL;
 102         TALLOC_CTX *ctx = talloc_stackframe();
 103         NTSTATUS status;
 104
 105         /* Check for absolute path */
 106
 107         /* if we make any 'samba multibyte string'
 108            calls here, we break
 109            for loading string modules */
 110
 111         DEBUG(5, ("Probing module '%s'\n", module));
 112
 113         if (module[0] == '/') {
 114                 status = do_smb_load_module(module, True);
 115                 TALLOC_FREE(ctx);
 116                 return status;
 117         }
 118
 119         full_path = talloc_asprintf(ctx,
 120                         "%s/%s.%s",
 121                         modules_path(subsystem),
 122                         module,
 123                         shlib_ext());
 124         if (!full_path) {
 125                 TALLOC_FREE(ctx);
 126                 return NT_STATUS_NO_MEMORY;
 127         }
 128
 129         DEBUG(5, ("Probing module '%s': Trying to load from %s\n",
 130                 module, full_path));
 131
 132         status = do_smb_load_module(full_path, True);
 133
 134         TALLOC_FREE(ctx);
 135         return status;
 136 }
 137
 138 #else /* HAVE_DLOPEN */
 139
 140 NTSTATUS smb_load_module(const char *module_name)
 141 {
 142         DEBUG(0,("This samba executable has not been built with plugin support\n"));
 143         return NT_STATUS_NOT_SUPPORTED;
 144 }
 145
 146 int smb_load_modules(const char **modules)
 147 {
 148         DEBUG(0,("This samba executable has not been built with plugin support\n"));
 149         return -1;
 150 }
 151
 152 NTSTATUS smb_probe_module(const char *subsystem, const char *module)
 153 {
 154         DEBUG(0,("This samba executable has not been built with plugin support, not probing\n"));
 155         return NT_STATUS_NOT_SUPPORTED;
 156 }
 157
 158 #endif /* HAVE_DLOPEN */
 159
 160 void init_modules(void)
 161 {
 162         /* FIXME: This can cause undefined symbol errors :
 163          *  smb_register_vfs() isn't available in nmbd, for example */
 164         if(lp_preload_modules())
 165                 smb_load_modules(lp_preload_modules());
 166 }