loader.c

   1 /*
   2  * Asterisk -- A telephony toolkit for Linux.
   3  *
   4  * Module Loader
   5  *
   6  * Copyright (C) 1999, Mark Spencer
   7  *
   8  * Mark Spencer <markster@linux-support.net>
   9  *
  10  * This program is free software, distributed under the terms of
  11  * the GNU General Public License
  12  */
  13
  14 #include <stdio.h>
  15 #include <dirent.h>
  16 #include <unistd.h>
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <asterisk/module.h>
  20 #include <asterisk/options.h>
  21 #include <asterisk/config.h>
  22 #include <asterisk/logger.h>
  23 #include <dlfcn.h>
  24 #define __USE_GNU
  25 #include <pthread.h>
  26 #include "asterisk.h"
  27
  28 struct module {
  29         int (*load_module)(void);
  30         int (*unload_module)(void);
  31         int (*usecount)(void);
  32         char *(*description)(void);
  33         void *lib;
  34         char resource[256];
  35         struct module *next;
  36 };
  37
  38 static struct loadupdate {
  39         int (*updater)(void);
  40         struct loadupdate *next;
  41 } *updaters = NULL;
  42
  43 static pthread_mutex_t modlock = PTHREAD_MUTEX_INITIALIZER;
  44
  45 static struct module *module_list=NULL;
  46
  47 int ast_unload_resource(char *resource_name, int force)
  48 {
  49         struct module *m, *ml = NULL;
  50         int res = -1;
  51         if (pthread_mutex_lock(&modlock))
  52                 ast_log(LOG_WARNING, "Failed to lock\n");
  53         m = module_list;
  54         while(m) {
  55                 if (!strcasecmp(m->resource, resource_name)) {
  56                         if ((res = m->usecount()) > 0)  {
  57                                 if (force)
  58                                         ast_log(LOG_WARNING, "Warning:  Forcing removal of module %s with use count %d\n", resource_name, res);
  59                                 else {
  60                                         ast_log(LOG_WARNING, "Soft unload failed, '%s' has use count %d\n", resource_name, res);
  61                                         pthread_mutex_unlock(&modlock);
  62                                         return -1;
  63                                 }
  64                         }
  65                         res = m->unload_module();
  66                         if (res) {
  67                                 ast_log(LOG_WARNING, "Firm unload failed for %s\n", resource_name);
  68                                 if (force <= AST_FORCE_FIRM) {
  69                                         pthread_mutex_unlock(&modlock);
  70                                         return -1;
  71                                 } else
  72                                         ast_log(LOG_WARNING, "** Dangerous **: Unloading resource anyway, at user request\n");
  73                         }
  74                         if (ml)
  75                                 ml->next = m->next;
  76                         else
  77                                 module_list = m->next;
  78                         dlclose(m->lib);
  79                         free(m);
  80                 }
  81                 ml = m;
  82                 m = m->next;
  83         }
  84         pthread_mutex_unlock(&modlock);
  85         ast_update_use_count();
  86         return res;
  87 }
  88
  89 int ast_load_resource(char *resource_name)
  90 {
  91         static char fn[256];
  92         int errors=0;
  93         int res;
  94         struct module *m;
  95         if (pthread_mutex_lock(&modlock))
  96                 ast_log(LOG_WARNING, "Failed to lock\n");
  97         m = module_list;
  98         while(m) {
  99                 if (!strcasecmp(m->resource, resource_name)) {
 100                         ast_log(LOG_WARNING, "Module '%s' already exists\n", resource_name);
 101                         pthread_mutex_unlock(&modlock);
 102                         return -1;
 103                 }
 104                 m = m->next;
 105         }
 106         m = malloc(sizeof(struct module));
 107         if (!m) {
 108                 ast_log(LOG_WARNING, "Out of memory\n");
 109                 pthread_mutex_unlock(&modlock);
 110                 return -1;
 111         }
 112         strncpy(m->resource, resource_name, sizeof(m->resource));
 113         if (resource_name[0] == '/') {
 114                 strncpy(fn, resource_name, sizeof(fn));
 115         } else {
 116                 snprintf(fn, sizeof(fn), "%s/%s", AST_MODULE_DIR, resource_name);
 117         }
 118         m->lib = dlopen(fn, RTLD_NOW  | RTLD_GLOBAL);
 119         if (!m->lib) {
 120                 ast_log(LOG_WARNING, "%s\n", dlerror());
 121                 free(m);
 122                 pthread_mutex_unlock(&modlock);
 123                 return -1;
 124         }
 125         m->load_module = dlsym(m->lib, "load_module");
 126         if (!m->load_module) {
 127                 ast_log(LOG_WARNING, "No load_module in module %s\n", fn);
 128                 errors++;
 129         }
 130         m->unload_module = dlsym(m->lib, "unload_module");
 131         if (!m->unload_module) {
 132                 ast_log(LOG_WARNING, "No unload_module in module %s\n", fn);
 133                 errors++;
 134         }
 135         m->usecount = dlsym(m->lib, "usecount");
 136         if (!m->usecount) {
 137                 ast_log(LOG_WARNING, "No usecount in module %s\n", fn);
 138                 errors++;
 139         }
 140         m->description = dlsym(m->lib, "description");
 141         if (!m->description) {
 142                 ast_log(LOG_WARNING, "No description in module %s\n", fn);
 143                 errors++;
 144         }
 145         if (errors) {
 146                 ast_log(LOG_WARNING, "%d error(s) loading module %s, aborted\n", errors, fn);
 147                 dlclose(m->lib);
 148                 free(m);
 149                 pthread_mutex_unlock(&modlock);
 150                 return -1;
 151         }
 152         if (option_verbose)
 153                 ast_verbose( " => (%s)\n", m->description());
 154         pthread_mutex_unlock(&modlock);
 155         if ((res = m->load_module())) {
 156                 ast_log(LOG_WARNING, "%s: load_module failed, returning %d\n", m->resource, fn, res);
 157                 ast_unload_resource(resource_name, 0);
 158                 return -1;
 159         }
 160         m->next = module_list;
 161         module_list = m;
 162         return 0;
 163 }
 164
 165 static int ast_resource_exists(char *resource)
 166 {
 167         struct module *m;
 168         if (pthread_mutex_lock(&modlock))
 169                 ast_log(LOG_WARNING, "Failed to lock\n");
 170         m = module_list;
 171         while(m) {
 172                 if (!strcasecmp(resource, m->resource))
 173                         break;
 174                 m = m->next;
 175         }
 176         pthread_mutex_unlock(&modlock);
 177         if (m)
 178                 return -1;
 179         else
 180                 return 0;
 181 }
 182
 183 int load_modules()
 184 {
 185         struct ast_config *cfg;
 186         struct ast_variable *v;
 187         if (option_verbose)
 188                 ast_verbose( "Asterisk Dynamic Loader Starting:\n");
 189         cfg = ast_load(AST_MODULE_CONFIG);
 190         if (cfg) {
 191                 /* Load explicitly defined modules */
 192                 v = ast_variable_browse(cfg, "modules");
 193                 while(v) {
 194                         if (!strcasecmp(v->name, "load")) {
 195                                 if (option_debug && !option_verbose)
 196                                         ast_log(LOG_DEBUG, "Loading module %s\n", v->value);
 197                                 if (option_verbose) {
 198                                         ast_verbose( " [%s]", v->value);
 199                                         fflush(stdout);
 200                                 }
 201                                 if (ast_load_resource(v->value)) {
 202                                         ast_log(LOG_WARNING, "Loading module %s failed!\n", v->value);
 203                                         if (cfg)
 204                                                 ast_destroy(cfg);
 205                                         return -1;
 206                                 }
 207                         }
 208                         v=v->next;
 209                 }
 210         }
 211         if (!cfg || ast_true(ast_variable_retrieve(cfg, "modules", "autoload"))) {
 212                 /* Load all modules */
 213                 DIR *mods;
 214                 struct dirent *d;
 215                 mods = opendir(AST_MODULE_DIR);
 216                 if (mods) {
 217                         while((d = readdir(mods))) {
 218                                 /* Must end in .so to load it.  */
 219                                 if ((strlen(d->d_name) > 3) &&
 220                                     !strcasecmp(d->d_name + strlen(d->d_name) - 3, ".so") &&
 221                                         !ast_resource_exists(d->d_name)) {
 222                                         /* It's a shared library -- Just be sure we're allowed to load it -- kinda
 223                                            an inefficient way to do it, but oh well. */
 224                                         if (cfg) {
 225                                                 v = ast_variable_browse(cfg, "modules");
 226                                                 while(v) {
 227                                                         if (!strcasecmp(v->name, "noload") &&
 228                                                             !strcasecmp(v->value, d->d_name))
 229                                                                 break;
 230                                                         v = v->next;
 231                                                 }
 232                                                 if (v) {
 233                                                         if (option_verbose) {
 234                                                                 ast_verbose( VERBOSE_PREFIX_1 "[skipping %s]\n", d->d_name);
 235                                                                 fflush(stdout);
 236                                                         }
 237                                                         continue;
 238                                                 }
 239
 240                                         }
 241                                     if (option_debug && !option_verbose)
 242                                                 ast_log(LOG_DEBUG, "Loading module %s\n", d->d_name);
 243                                         if (option_verbose) {
 244                                                 ast_verbose( VERBOSE_PREFIX_1 "[%s]", d->d_name);
 245                                                 fflush(stdout);
 246                                         }
 247                                         if (ast_load_resource(d->d_name)) {
 248                                                 ast_log(LOG_WARNING, "Loading module %s failed!\n", d->d_name);
 249                                                 if (cfg)
 250                                                         ast_destroy(cfg);
 251                                                 return -1;
 252                                         }
 253                                 }
 254                         };
 255                 } else {
 256                         if (!option_quiet)
 257                                 ast_log(LOG_WARNING, "Unable to open modules directory " AST_MODULE_DIR ".\n");
 258                 }
 259         }
 260         ast_destroy(cfg);
 261         return 0;
 262 }
 263
 264 void ast_update_use_count(void)
 265 {
 266         /* Notify any module monitors that the use count for a
 267            resource has changed */
 268         struct loadupdate *m;
 269         if (pthread_mutex_lock(&modlock))
 270                 ast_log(LOG_WARNING, "Failed to lock\n");
 271         m = updaters;
 272         while(m) {
 273                 m->updater();
 274                 m = m->next;
 275         }
 276         pthread_mutex_unlock(&modlock);
 277
 278 }
 279
 280 int ast_update_module_list(int (*modentry)(char *module, char *description, int usecnt))
 281 {
 282         struct module *m;
 283         int unlock = -1;
 284         if (pthread_mutex_trylock(&modlock))
 285                 unlock = 0;
 286         m = module_list;
 287         while(m) {
 288                 modentry(m->resource, m->description(), m->usecount());
 289                 m = m->next;
 290         }
 291         if (unlock)
 292                 pthread_mutex_unlock(&modlock);
 293         return 0;
 294 }
 295
 296 int ast_loader_register(int (*v)(void))
 297 {
 298         struct loadupdate *tmp;
 299         /* XXX Should be more flexible here, taking > 1 verboser XXX */
 300         if ((tmp = malloc(sizeof (struct loadupdate)))) {
 301                 tmp->updater = v;
 302                 if (pthread_mutex_lock(&modlock))
 303                         ast_log(LOG_WARNING, "Failed to lock\n");
 304                 tmp->next = updaters;
 305                 updaters = tmp;
 306                 pthread_mutex_unlock(&modlock);
 307                 return 0;
 308         }
 309         return -1;
 310 }
 311
 312 int ast_loader_unregister(int (*v)(void))
 313 {
 314         int res = -1;
 315         struct loadupdate *tmp, *tmpl=NULL;
 316         if (pthread_mutex_lock(&modlock))
 317                 ast_log(LOG_WARNING, "Failed to lock\n");
 318         tmp = updaters;
 319         while(tmp) {
 320                 if (tmp->updater == v)  {
 321                         if (tmpl)
 322                                 tmpl->next = tmp->next;
 323                         else
 324                                 updaters = tmp->next;
 325                         break;
 326                 }
 327                 tmpl = tmp;
 328                 tmp = tmp->next;
 329         }
 330         if (tmp)
 331                 res = 0;
 332         pthread_mutex_unlock(&modlock);
 333         return res;
 334 }