| | 1 | /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*- |
| | 2 | * |
| | 3 | * Copyright (c) 2004-2005 Apple Computer, 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 syncronization utilities used by dyld to be thread safe. |
| | 31 | // Access to all dyld data structures is protected by a reader-writer lock. |
| | 32 | // This lock allows multiple "reader" threads to access dyld data structures at |
| | 33 | // the same time. If there is a "writer" thread, it is the only thread allowed |
| | 34 | // access to dyld data structures. |
| | 35 | // |
| | 36 | // The implementation of all dyld API's must acquire the global lock around accesses |
| | 37 | // to dyld's data structures. This is done using the macros DYLD_*_LOCK_THIS_BLOCK. |
| | 38 | // Example: |
| | 39 | // |
| | 40 | // void dyld_api_modifying_dyld() { |
| | 41 | // DYLD_WRITER_LOCK_THIS_BLOCK; |
| | 42 | // // free to do stuff here |
| | 43 | // // that modifies dyld data structures |
| | 44 | // } |
| | 45 | // |
| | 46 | // void dyld_api_examinging_dyld() { |
| | 47 | // DYLD_READER_LOCK_THIS_BLOCK |
| | 48 | // // can only do stuff here |
| | 49 | // // that examines but does not modify dyld data structures |
| | 50 | // } |
| | 51 | // |
| | 52 | // void dyld_api_state_free() { |
| | 53 | // DYLD_NO_LOCK_THIS_BLOCK |
| | 54 | // // can only do stuff here |
| | 55 | // // that does not require locking |
| | 56 | // } |
| | 57 | // |
| | 58 | |
| | 59 | |
| | 60 | #define DYLD_READER_LOCK_THIS_BLOCK LockReaderHelper _dyld_lock; |
| | 61 | #define DYLD_WRITER_LOCK_THIS_BLOCK LockWriterHelper _dyld_lock; |
| | 62 | #define DYLD_NO_LOCK_THIS_BLOCK |
| | 63 | |
| | 64 | // used by dyld wrapper functions in libSystem |
| | 65 | class LockReaderHelper |
| | 66 | { |
| | 67 | public: |
| | 68 | LockReaderHelper() __attribute__((visibility("hidden"))); |
| | 69 | ~LockReaderHelper() __attribute__((visibility("hidden"))); |
| | 70 | }; |
| | 71 | |
| | 72 | // used by dyld wrapper functions in libSystem |
| | 73 | class LockWriterHelper |
| | 74 | { |
| | 75 | public: |
| | 76 | LockWriterHelper() __attribute__((visibility("hidden"))); |
| | 77 | ~LockWriterHelper() __attribute__((visibility("hidden"))); |
| | 78 | }; |
| | 79 | |
| | 80 | // used by lazy binding |
| | 81 | extern void lockForLazyBinding() __attribute__((visibility("hidden"))); |
| | 82 | extern void unlockForLazyBinding() __attribute__((visibility("hidden"))); |
| | 83 | |
| | 84 | |
| | 85 | |
| | 86 | #endif // __DYLDLOCK__ |
| | 87 | |
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