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 58
