1/*	$NetBSD$	*/
2
3/*
4 * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
5 * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
6 *
7 * This file is part of LVM2.
8 *
9 * This copyrighted material is made available to anyone wishing to use,
10 * modify, copy, or redistribute it subject to the terms and conditions
11 * of the GNU Lesser General Public License v.2.1.
12 *
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
16 */
17
18#include "lib.h"
19#include "locking_types.h"
20#include "defaults.h"
21#include "sharedlib.h"
22#include "toolcontext.h"
23
24static void *_locking_lib = NULL;
25static void (*_reset_fn) (void) = NULL;
26static void (*_end_fn) (void) = NULL;
27static int (*_lock_fn) (struct cmd_context * cmd, const char *resource,
28			uint32_t flags) = NULL;
29static int (*_init_fn) (int type, struct config_tree * cft,
30			uint32_t *flags) = NULL;
31static int (*_lock_query_fn) (const char *resource, int *mode) = NULL;
32
33static int _lock_resource(struct cmd_context *cmd, const char *resource,
34			  uint32_t flags)
35{
36	if (_lock_fn)
37		return _lock_fn(cmd, resource, flags);
38	else
39		return 0;
40}
41
42static void _fin_external_locking(void)
43{
44	if (_end_fn)
45		_end_fn();
46
47	dlclose(_locking_lib);
48
49	_locking_lib = NULL;
50	_init_fn = NULL;
51	_end_fn = NULL;
52	_lock_fn = NULL;
53	_reset_fn = NULL;
54}
55
56static void _reset_external_locking(void)
57{
58	if (_reset_fn)
59		_reset_fn();
60}
61
62int init_external_locking(struct locking_type *locking, struct cmd_context *cmd)
63{
64	const char *libname;
65
66	if (_locking_lib) {
67		log_error("External locking already initialised");
68		return 1;
69	}
70
71	locking->lock_resource = _lock_resource;
72	locking->fin_locking = _fin_external_locking;
73	locking->reset_locking = _reset_external_locking;
74	locking->flags = 0;
75
76	libname = find_config_tree_str(cmd, "global/locking_library",
77				       DEFAULT_LOCKING_LIB);
78
79	if (!(_locking_lib = load_shared_library(cmd, libname, "locking", 1)))
80		return_0;
81
82	/* Get the functions we need */
83	if (!(_init_fn = dlsym(_locking_lib, "locking_init")) ||
84	    !(_lock_fn = dlsym(_locking_lib, "lock_resource")) ||
85	    !(_reset_fn = dlsym(_locking_lib, "reset_locking")) ||
86	    !(_end_fn = dlsym(_locking_lib, "locking_end"))) {
87		log_error("Shared library %s does not contain locking "
88			  "functions", libname);
89		dlclose(_locking_lib);
90		_locking_lib = NULL;
91		return 0;
92	}
93
94	if (!(_lock_query_fn = dlsym(_locking_lib, "query_resource")))
95		log_warn("WARNING: %s: _query_resource() missing: "
96			 "Using inferior activation method.", libname);
97
98	log_verbose("Loaded external locking library %s", libname);
99	return _init_fn(2, cmd->cft, &locking->flags);
100}
101