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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <libnl++/MessageMutator.h>
namespace android::nl {
MessageMutator::MessageMutator(nlmsghdr* buffer, size_t totalLen)
: mMutableBuffer(buffer), mTotalLen(totalLen) {
CHECK(totalLen >= sizeof(nlmsghdr));
}
nlmsghdr* MessageMutator::operator->() const {
return mMutableBuffer;
}
Buffer<nlmsghdr> MessageMutator::constBuffer() const {
return {mMutableBuffer, mTotalLen};
}
MessageMutator::operator Buffer<nlmsghdr>() const {
return constBuffer();
}
uint64_t MessageMutator::read(Buffer<nlattr> attr) const {
return attr.data<uint64_t>().copyFirst();
}
void MessageMutator::write(Buffer<nlattr> attr, uint64_t val) const {
const auto attrData = attr.data<uint64_t>();
// TODO(b/177251183): deduplicate this code against fragment()
const auto offset = constBuffer().getOffset(attrData);
CHECK(offset.has_value()) << "Trying to write attribute that's not a member of this message";
const auto writeableBuffer = reinterpret_cast<uint8_t*>(mMutableBuffer) + *offset;
const auto attrSize = attrData.getRaw().len();
if (attrSize > sizeof(val)) memset(writeableBuffer, 0, attrSize);
memcpy(writeableBuffer, &val, std::min(sizeof(val), attrSize));
}
MessageMutator MessageMutator::fragment(Buffer<nlmsghdr> buf) const {
const auto offset = constBuffer().getOffset(buf);
CHECK(offset.has_value()) << "Trying to modify a fragment outside of buffer range";
const auto writeableBuffer = reinterpret_cast<nlmsghdr*>(uintptr_t(mMutableBuffer) + *offset);
const auto len = buf.getRaw().len();
CHECK(len <= mTotalLen - *offset);
return {writeableBuffer, len};
}
MessageMutator::iterator MessageMutator::begin() const {
return {*this, constBuffer().begin()};
}
MessageMutator::iterator MessageMutator::end() const {
return {*this, constBuffer().end()};
}
MessageMutator::iterator::iterator(const MessageMutator& container,
Buffer<nlmsghdr>::iterator current)
: mContainer(container), mCurrent(current) {}
MessageMutator::iterator MessageMutator::iterator::operator++() {
++mCurrent;
return *this;
}
bool MessageMutator::iterator::operator==(const iterator& other) const {
return other.mCurrent == mCurrent;
}
const MessageMutator MessageMutator::iterator::operator*() const {
return mContainer.fragment(*mCurrent);
}
} // namespace android::nl
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