1/* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
2 *
3 * Copyright (c) 2004-2012 Apple Inc. All rights reserved.
4 *
5 * @APPLE_LICENSE_HEADER_START@
6 *
7 * This file contains Original Code and/or Modifications of Original Code
8 * as defined in and that are subject to the Apple Public Source License
9 * Version 2.0 (the 'License'). You may not use this file except in
10 * compliance with the License. Please obtain a copy of the License at
11 * http://www.opensource.apple.com/apsl/ and read it before using this
12 * file.
13 *
14 * The Original Code and all software distributed under the License are
15 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
16 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
17 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
19 * Please see the License for the specific language governing rights and
20 * limitations under the License.
21 *
22 * @APPLE_LICENSE_HEADER_END@
23 */
24
25
26#ifndef __DYLDLOCK__
27#define __DYLDLOCK__
28
29//
30// This file contains the synchronization utilities used to make dyld APIs be thread safe.
31//
32// The implementation of all dyld API's must hold acquire global lock (in libSystem)
33// before calling into dyld proper, and release the lock after returning from dyld.
34// This is done using the macros DYLD_LOCK_THIS_BLOCK.
35// Example:
36//
37//  void dyld_api() {
38//		DYLD_LOCK_THIS_BLOCK;
39//		// free to do stuff here
40//		// that accesses dyld internal data structures
41//	}
42//
43//  void dyld_api_state_free() {
44//		DYLD_NO_LOCK_THIS_BLOCK
45//		// can only do stuff here
46//		// that does not require locking
47//	}
48//
49
50#define DYLD_LOCK_THIS_BLOCK			LockHelper _dyld_lock;
51#define DYLD_NO_LOCK_THIS_BLOCK
52
53// used by dyld wrapper functions in libSystem
54class __attribute__((visibility("hidden"))) LockHelper
55{
56public:
57	LockHelper();
58	~LockHelper();
59};
60
61
62// to initialize
63extern void dyldGlobalLockInitialize()		__attribute__((visibility("hidden")));
64extern void dyldGlobalLockAcquire()			__attribute__((visibility("hidden")));
65extern void dyldGlobalLockRelease()			__attribute__((visibility("hidden")));
66
67#endif // __DYLDLOCK__
68
69