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ldb_modules.c

/* 
   ldb database library

   Copyright (C) Simo Sorce  2004

     ** NOTE! The following LGPL license applies to the ldb
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

/*
 *  Name: ldb
 *
 *  Component: ldb modules core
 *
 *  Description: core modules routines
 *
 *  Author: Simo Sorce
 */

#include "ldb_includes.h"

#if (_SAMBA_BUILD_ >= 4)
#include "includes.h"
#include "build.h"
#include "dynconfig.h"
#endif

#define LDB_MODULE_PREFIX     "modules:"
#define LDB_MODULE_PREFIX_LEN 8

static char *ldb_modules_strdup_no_spaces(TALLOC_CTX *mem_ctx, const char *string)
{
      int i, len;
      char *trimmed;

      trimmed = talloc_strdup(mem_ctx, string);
      if (!trimmed) {
            return NULL;
      }

      len = strlen(trimmed);
      for (i = 0; trimmed[i] != '\0'; i++) {
            switch (trimmed[i]) {
            case ' ':
            case '\t':
            case '\n':
                  memmove(&trimmed[i], &trimmed[i + 1], len -i -1);
                  break;
            }
      }

      return trimmed;
}


/* modules are called in inverse order on the stack.
   Lets place them as an admin would think the right order is.
   Modules order is important */
const char **ldb_modules_list_from_string(struct ldb_context *ldb, TALLOC_CTX *mem_ctx, const char *string)
{
      char **modules = NULL;
      const char **m;
      char *modstr, *p;
      int i;

      /* spaces not admitted */
      modstr = ldb_modules_strdup_no_spaces(mem_ctx, string);
      if ( ! modstr) {
            ldb_debug(ldb, LDB_DEBUG_FATAL, "Out of Memory in ldb_modules_strdup_no_spaces()\n");
            return NULL;
      }

      modules = talloc_realloc(mem_ctx, modules, char *, 2);
      if ( ! modules ) {
            ldb_debug(ldb, LDB_DEBUG_FATAL, "Out of Memory in ldb_modules_list_from_string()\n");
            talloc_free(modstr);
            return NULL;
      }
      talloc_steal(modules, modstr);

      i = 0;
      /* The str*r*chr walks backwards:  This is how we get the inverse order mentioned above */
      while ((p = strrchr(modstr, ',')) != NULL) {
            *p = '\0';
            p++;
            modules[i] = p;

            i++;
            modules = talloc_realloc(mem_ctx, modules, char *, i + 2);
            if ( ! modules ) {
                  ldb_debug(ldb, LDB_DEBUG_FATAL, "Out of Memory in ldb_modules_list_from_string()\n");
                  return NULL;
            }

      }
      modules[i] = modstr;

      modules[i + 1] = NULL;

      m = (const char **)modules;

      return m;
}

static struct ops_list_entry {
      const struct ldb_module_ops *ops;
      struct ops_list_entry *next;  
} *registered_modules = NULL;

static const struct ldb_module_ops *ldb_find_module_ops(const char *name)
{
      struct ops_list_entry *e;
 
      for (e = registered_modules; e; e = e->next) {
            if (strcmp(e->ops->name, name) == 0) 
                  return e->ops;
      }

      return NULL;
}

#ifndef STATIC_ldb_MODULES

#ifdef HAVE_LDB_LDAP
#define LDAP_INIT ldb_ldap_init,
#else
#define LDAP_INIT
#endif

#ifdef HAVE_LDB_SQLITE3
#define SQLITE3_INIT ldb_sqlite3_init,
#else
#define SQLITE3_INIT
#endif

#define STATIC_ldb_MODULES \
      {     \
            LDAP_INIT \
            SQLITE3_INIT \
            ldb_tdb_init,     \
            ldb_operational_init,   \
            ldb_rdn_name_init,      \
            ldb_objectclass_init,   \
            ldb_paged_results_init, \
            ldb_sort_init,          \
            ldb_asq_init,           \
            NULL              \
      }
#endif

00167 int ldb_global_init(void)
{
      static int (*static_init_fns[])(void) = STATIC_ldb_MODULES;

      static int initialized = 0;
      int ret = 0, i;

      if (initialized) 
            return 0;

      initialized = 1;
      
      for (i = 0; static_init_fns[i]; i++) {
            if (static_init_fns[i]() == -1)
                  ret = -1;
      }

      return ret;
}

int ldb_register_module(const struct ldb_module_ops *ops)
{
      struct ops_list_entry *entry = talloc(talloc_autofree_context(), struct ops_list_entry);

      if (ldb_find_module_ops(ops->name) != NULL)
            return -1;

      if (entry == NULL)
            return -1;

      entry->ops = ops;
      entry->next = registered_modules;
      registered_modules = entry;

      return 0;
}

int ldb_try_load_dso(struct ldb_context *ldb, const char *name)
{
      char *path;
      void *handle;
      int (*init_fn) (void);
      char *modulesdir;

#ifdef HAVE_DLOPEN
      if (getenv("LD_LDB_MODULE_PATH") != NULL) {
            modulesdir = talloc_strdup(ldb, getenv("LD_LDB_MODULE_PATH"));
      } else {
#ifdef _SAMBA_BUILD_
            modulesdir = talloc_asprintf(ldb, "%s/ldb", dyn_MODULESDIR);
#else
            modulesdir = talloc_strdup(ldb, MODULESDIR);
#endif
      }

      path = talloc_asprintf(ldb, "%s/%s.%s", modulesdir, name, SHLIBEXT);

      talloc_free(modulesdir);

      ldb_debug(ldb, LDB_DEBUG_TRACE, "trying to load %s from %s\n", name, path);

      handle = dlopen(path, RTLD_NOW);
      if (handle == NULL) {
            ldb_debug(ldb, LDB_DEBUG_WARNING, "unable to load %s from %s: %s\n", name, path, dlerror());
            return -1;
      }

      init_fn = (int (*)(void))dlsym(handle, "init_module");

      if (init_fn == NULL) {
            ldb_debug(ldb, LDB_DEBUG_ERROR, "no symbol `init_module' found in %s: %s\n", path, dlerror());
            return -1;
      }

      talloc_free(path);

      return init_fn();
#else
      ldb_debug(ldb, LDB_DEBUG_TRACE, "no dlopen() - not trying to load %s module\n", name);
      return -1;
#endif
}

int ldb_load_modules_list(struct ldb_context *ldb, const char **module_list, struct ldb_module *backend, struct ldb_module **out)
{
      struct ldb_module *module;
      int i;
      
      module = backend;

      for (i = 0; module_list[i] != NULL; i++) {
            struct ldb_module *current;
            const struct ldb_module_ops *ops;
            
            ops = ldb_find_module_ops(module_list[i]);
            if (ops == NULL) {
                  if (ldb_try_load_dso(ldb, module_list[i]) == 0) {
                        ops = ldb_find_module_ops(module_list[i]);
                  }
            }
            
            if (ops == NULL) {
                  ldb_debug(ldb, LDB_DEBUG_WARNING, "WARNING: Module [%s] not found\n", 
                          module_list[i]);
                  continue;
            }
            
            current = talloc_zero(ldb, struct ldb_module);
            if (current == NULL) {
                  return LDB_ERR_OPERATIONS_ERROR;
            }
            talloc_set_name(current, "ldb_module: %s", module_list[i]);
            
            current->ldb = ldb;
            current->ops = ops;
            
            DLIST_ADD(module, current);
      }
      *out = module;
      return LDB_SUCCESS;
}

int ldb_init_module_chain(struct ldb_context *ldb, struct ldb_module *module) 
{
      while (module && module->ops->init_context == NULL) 
            module = module->next;

      if (module && module->ops->init_context &&
            module->ops->init_context(module) != LDB_SUCCESS) {
            ldb_debug(ldb, LDB_DEBUG_FATAL, "module initialization failed\n");
            return LDB_ERR_OPERATIONS_ERROR;
      }

      return LDB_SUCCESS;
}

int ldb_load_modules(struct ldb_context *ldb, const char *options[])
{
      const char **modules = NULL;
      int i;
      int ret;
      TALLOC_CTX *mem_ctx = talloc_new(ldb);
      if (!mem_ctx) {
            return LDB_ERR_OPERATIONS_ERROR;
      }

      /* find out which modules we are requested to activate */

      /* check if we have a custom module list passd as ldb option */
      if (options) {
            for (i = 0; options[i] != NULL; i++) {
                  if (strncmp(options[i], LDB_MODULE_PREFIX, LDB_MODULE_PREFIX_LEN) == 0) {
                        modules = ldb_modules_list_from_string(ldb, mem_ctx, &options[i][LDB_MODULE_PREFIX_LEN]);
                  }
            }
      }

      /* if not overloaded by options and the backend is not ldap try to load the modules list from ldb */
      if ((modules == NULL) && (strcmp("ldap", ldb->modules->ops->name) != 0)) { 
            const char * const attrs[] = { "@LIST" , NULL};
            struct ldb_result *res = NULL;
            struct ldb_dn *mods_dn;

            mods_dn = ldb_dn_new(mem_ctx, ldb, "@MODULES");
            if (mods_dn == NULL) {
                  talloc_free(mem_ctx);
                  return -1;
            }

            ret = ldb_search(ldb, mods_dn, LDB_SCOPE_BASE, "", attrs, &res);
            talloc_steal(mods_dn, res);
            if (ret == LDB_SUCCESS && (res->count == 0 || res->msgs[0]->num_elements == 0)) {
                  ldb_debug(ldb, LDB_DEBUG_TRACE, "no modules required by the db\n");
            } else {
                  if (ret != LDB_SUCCESS) {
                        ldb_debug(ldb, LDB_DEBUG_FATAL, "ldb error (%s) occurred searching for modules, bailing out\n", ldb_errstring(ldb));
                        talloc_free(mem_ctx);
                        return -1;
                  }
                  if (res->count > 1) {
                        ldb_debug(ldb, LDB_DEBUG_FATAL, "Too many records found (%d), bailing out\n", res->count);
                        talloc_free(mem_ctx);
                        return -1;
                  }

                  modules = ldb_modules_list_from_string(ldb, mem_ctx,
                                                 (const char *)res->msgs[0]->elements[0].values[0].data);

            }

            talloc_free(mods_dn);
      }

      if (modules != NULL) {
            ret = ldb_load_modules_list(ldb, modules, ldb->modules, &ldb->modules);
            talloc_free(modules);
            if (ret != LDB_SUCCESS) {
                  return ret;
            }
      } else {
            ldb_debug(ldb, LDB_DEBUG_TRACE, "No modules specified for this database\n");
      }

      return ldb_init_module_chain(ldb, ldb->modules);
}

/*
  by using this we allow ldb modules to only implement the functions they care about,
  which makes writing a module simpler, and makes it more likely to keep working
  when ldb is extended
*/
#define FIND_OP(module, op) do { \
      struct ldb_context *ldb = module->ldb; \
      module = module->next; \
      while (module && module->ops->op == NULL) module = module->next; \
      if (module == NULL) { \
            ldb_asprintf_errstring(ldb, "Unable to find backend operation for " #op ); \
            return LDB_ERR_OPERATIONS_ERROR;    \
      }                                   \
} while (0)


/*
   helper functions to call the next module in chain
*/

int ldb_next_request(struct ldb_module *module, struct ldb_request *request)
{
      int ret;
      switch (request->operation) {
      case LDB_SEARCH:
            FIND_OP(module, search);
            ret = module->ops->search(module, request);
            break;
      case LDB_ADD:
            FIND_OP(module, add);
            ret = module->ops->add(module, request);
            break;
      case LDB_MODIFY:
            FIND_OP(module, modify);
            ret = module->ops->modify(module, request);
            break;
      case LDB_DELETE:
            FIND_OP(module, del);
            ret = module->ops->del(module, request);
            break;
      case LDB_RENAME:
            FIND_OP(module, rename);
            ret = module->ops->rename(module, request);
            break;
      case LDB_EXTENDED:
            FIND_OP(module, extended);
            ret = module->ops->extended(module, request);
            break;
      case LDB_SEQUENCE_NUMBER:
            FIND_OP(module, sequence_number);
            ret = module->ops->sequence_number(module, request);
            break;
      default:
            FIND_OP(module, request);
            ret = module->ops->request(module, request);
            break;
      }
      if (ret == LDB_SUCCESS) {
            return ret;
      }
      if (!ldb_errstring(module->ldb)) {
            /* Set a default error string, to place the blame somewhere */
            ldb_asprintf_errstring(module->ldb, "error in module %s: %s (%d)", module->ops->name, ldb_strerror(ret), ret);
      }
      return ret;
}

int ldb_next_init(struct ldb_module *module)
{
      /* init is different in that it is not an error if modules
       * do not require initialization */

      module = module->next;

      while (module && module->ops->init_context == NULL) 
            module = module->next;

      if (module == NULL) 
            return LDB_SUCCESS;

      return module->ops->init_context(module);
}

int ldb_next_start_trans(struct ldb_module *module)
{
      FIND_OP(module, start_transaction);
      return module->ops->start_transaction(module);
}

int ldb_next_end_trans(struct ldb_module *module)
{
      FIND_OP(module, end_transaction);
      return module->ops->end_transaction(module);
}

int ldb_next_del_trans(struct ldb_module *module)
{
      FIND_OP(module, del_transaction);
      return module->ops->del_transaction(module);
}

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