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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #import "chrome/common/mac/objc_method_swizzle.h" | |
6 | |
7 #import "base/logging.h" | |
8 | |
9 namespace ObjcEvilDoers { | |
10 | |
11 Method GetImplementedInstanceMethod(Class aClass, SEL aSelector) { | |
12 Method method = NULL; | |
13 unsigned int methodCount = 0; | |
14 Method* methodList = class_copyMethodList(aClass, &methodCount); | |
15 if (methodList) { | |
16 for (unsigned int i = 0; i < methodCount; ++i) { | |
17 if (method_getName(methodList[i]) == aSelector) { | |
18 method = methodList[i]; | |
19 break; | |
20 } | |
21 } | |
22 free(methodList); | |
23 } | |
24 return method; | |
25 } | |
26 | |
27 IMP SwizzleImplementedInstanceMethods( | |
28 Class aClass, const SEL originalSelector, const SEL alternateSelector) { | |
29 // The methods must both be implemented by the target class, not | |
30 // inherited from a superclass. | |
31 Method original = GetImplementedInstanceMethod(aClass, originalSelector); | |
32 Method alternate = GetImplementedInstanceMethod(aClass, alternateSelector); | |
33 DCHECK(original); | |
34 DCHECK(alternate); | |
35 if (!original || !alternate) { | |
36 return NULL; | |
37 } | |
38 | |
39 // The argument and return types must match exactly. | |
40 const char* originalTypes = method_getTypeEncoding(original); | |
41 const char* alternateTypes = method_getTypeEncoding(alternate); | |
42 DCHECK(originalTypes); | |
43 DCHECK(alternateTypes); | |
44 DCHECK(0 == strcmp(originalTypes, alternateTypes)); | |
45 if (!originalTypes || !alternateTypes || | |
46 strcmp(originalTypes, alternateTypes)) { | |
47 return NULL; | |
48 } | |
49 | |
50 IMP ret = method_getImplementation(original); | |
51 if (ret) { | |
52 method_exchangeImplementations(original, alternate); | |
53 } | |
54 return ret; | |
55 } | |
56 | |
57 } // namespace ObjcEvilDoers | |
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