1/*
2 * Copyright (c) 2005-2008 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. Please obtain a copy of the License at
10 * http://www.opensource.apple.com/apsl/ and read it before using this
11 * file.
12 *
13 * The Original Code and all software distributed under the License are
14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18 * Please see the License for the specific language governing rights and
19 * limitations under the License.
20 *
21 * @APPLE_LICENSE_HEADER_END@
22 */
23
24#if !defined(_DYLD_INTERPOSING_H_)
25#define _DYLD_INTERPOSING_H_
26
27/*
28 *  Example:
29 *
30 *  static
31 *  int
32 *  my_open(const char* path, int flags, mode_t mode)
33 *  {
34 *    int value;
35 *    // do stuff before open (including changing the arguments)
36 *    value = open(path, flags, mode);
37 *    // do stuff after open (including changing the return value(s))
38 *    return value;
39 *  }
40 *  DYLD_INTERPOSE(my_open, open)
41 */
42
43#define DYLD_INTERPOSE(_replacement,_replacee) \
44   __attribute__((used)) static struct{ const void* replacement; const void* replacee; } _interpose_##_replacee \
45            __attribute__ ((section ("__DATA,__interpose"))) = { (const void*)(unsigned long)&_replacement, (const void*)(unsigned long)&_replacee };
46
47#endif
48