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72 lines
2.5 KiB
Plaintext
72 lines
2.5 KiB
Plaintext
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// Copyright 2014 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#import "base/mac/scoped_objc_class_swizzler.h"
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#include <string.h>
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#include "base/logging.h"
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namespace base {
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namespace mac {
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ScopedObjCClassSwizzler::ScopedObjCClassSwizzler(Class target,
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Class source,
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SEL selector)
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: old_selector_impl_(NULL), new_selector_impl_(NULL) {
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Init(target, source, selector, selector);
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}
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ScopedObjCClassSwizzler::ScopedObjCClassSwizzler(Class target,
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SEL original,
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SEL alternate)
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: old_selector_impl_(NULL), new_selector_impl_(NULL) {
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Init(target, target, original, alternate);
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}
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ScopedObjCClassSwizzler::~ScopedObjCClassSwizzler() {
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if (old_selector_impl_ && new_selector_impl_)
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method_exchangeImplementations(old_selector_impl_, new_selector_impl_);
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}
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IMP ScopedObjCClassSwizzler::GetOriginalImplementation() {
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// Note that while the swizzle is in effect the "new" method is actually
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// pointing to the original implementation, since they have been swapped.
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return method_getImplementation(new_selector_impl_);
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}
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void ScopedObjCClassSwizzler::Init(Class target,
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Class source,
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SEL original,
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SEL alternate) {
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old_selector_impl_ = class_getInstanceMethod(target, original);
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new_selector_impl_ = class_getInstanceMethod(source, alternate);
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if (!old_selector_impl_ && !new_selector_impl_) {
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// Try class methods.
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old_selector_impl_ = class_getClassMethod(target, original);
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new_selector_impl_ = class_getClassMethod(source, alternate);
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}
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DCHECK(old_selector_impl_);
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DCHECK(new_selector_impl_);
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if (!old_selector_impl_ || !new_selector_impl_)
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return;
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// The argument and return types must match exactly.
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const char* old_types = method_getTypeEncoding(old_selector_impl_);
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const char* new_types = method_getTypeEncoding(new_selector_impl_);
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DCHECK(old_types);
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DCHECK(new_types);
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DCHECK_EQ(0, strcmp(old_types, new_types));
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if (!old_types || !new_types || strcmp(old_types, new_types)) {
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old_selector_impl_ = new_selector_impl_ = NULL;
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return;
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}
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method_exchangeImplementations(old_selector_impl_, new_selector_impl_);
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}
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} // namespace mac
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} // namespace base
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