projects / apple / dyld.git / blame
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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 |