text: /*	$NetBSD: external_locking.c,v 1.1.1.2 2009/12/02 00:26:24 haad Exp $	*/
  
  /*
   * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
   * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
   *
   * This file is part of LVM2.
   *
   * This copyrighted material is made available to anyone wishing to use,
   * modify, copy, or redistribute it subject to the terms and conditions
   * of the GNU Lesser General Public License v.2.1.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include "lib.h"
  #include "locking_types.h"
  #include "defaults.h"
  #include "sharedlib.h"
  #include "toolcontext.h"
  
  static void *_locking_lib = NULL;
  static void (*_reset_fn) (void) = NULL;
  static void (*_end_fn) (void) = NULL;
  static int (*_lock_fn) (struct cmd_context * cmd, const char *resource,
  			uint32_t flags) = NULL;
  static int (*_init_fn) (int type, struct config_tree * cft,
  			uint32_t *flags) = NULL;
  static int (*_lock_query_fn) (const char *resource, int *mode) = NULL;
  
  static int _lock_resource(struct cmd_context *cmd, const char *resource,
  			  uint32_t flags)
  {
  	if (_lock_fn)
  		return _lock_fn(cmd, resource, flags);
  	else
  		return 0;
  }
  
  static void _fin_external_locking(void)
  {
  	if (_end_fn)
  		_end_fn();
  
  	dlclose(_locking_lib);
  
  	_locking_lib = NULL;
  	_init_fn = NULL;
  	_end_fn = NULL;
  	_lock_fn = NULL;
  	_reset_fn = NULL;
  }
  
  static void _reset_external_locking(void)
  {
  	if (_reset_fn)
  		_reset_fn();
  }
  
  int init_external_locking(struct locking_type *locking, struct cmd_context *cmd)
  {
  	const char *libname;
  
  	if (_locking_lib) {
  		log_error("External locking already initialised");
  		return 1;
  	}
  
  	locking->lock_resource = _lock_resource;
  	locking->fin_locking = _fin_external_locking;
  	locking->reset_locking = _reset_external_locking;
  	locking->flags = 0;
  
  	libname = find_config_tree_str(cmd, "global/locking_library",
  				       DEFAULT_LOCKING_LIB);
  
  	if (!(_locking_lib = load_shared_library(cmd, libname, "locking", 1)))
  		return_0;
  
  	/* Get the functions we need */
  	if (!(_init_fn = dlsym(_locking_lib, "locking_init")) ||
  	    !(_lock_fn = dlsym(_locking_lib, "lock_resource")) ||
  	    !(_reset_fn = dlsym(_locking_lib, "reset_locking")) ||
  	    !(_end_fn = dlsym(_locking_lib, "locking_end"))) {
  		log_error("Shared library %s does not contain locking "
  			  "functions", libname);
  		dlclose(_locking_lib);
  		_locking_lib = NULL;
  		return 0;
  	}
  
  	if (!(_lock_query_fn = dlsym(_locking_lib, "query_resource")))
  		log_warn("WARNING: %s: _query_resource() missing: "
  			 "Using inferior activation method.", libname);
  
  	log_verbose("Loaded external locking library %s", libname);
  	return _init_fn(2, cmd->cft, &locking->flags);
  }
  