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104 lines
3.3 KiB
104 lines
3.3 KiB
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_LIBELFFILE_STREAM_ERROR_DELAYING_OUTPUT_STREAM_H_
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#define ART_LIBELFFILE_STREAM_ERROR_DELAYING_OUTPUT_STREAM_H_
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#include "output_stream.h"
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#include <android-base/logging.h>
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#include "base/macros.h"
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namespace art {
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// OutputStream wrapper that delays reporting an error until Flush().
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class ErrorDelayingOutputStream final : public OutputStream {
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public:
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explicit ErrorDelayingOutputStream(OutputStream* output)
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: OutputStream(output->GetLocation()),
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output_(output),
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output_good_(true),
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output_offset_(0) { }
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// This function always succeeds to simplify code.
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// Use Good() to check the actual status of the output stream.
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bool WriteFully(const void* buffer, size_t byte_count) override {
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if (output_good_) {
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if (!output_->WriteFully(buffer, byte_count)) {
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PLOG(ERROR) << "Failed to write " << byte_count
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<< " bytes to " << GetLocation() << " at offset " << output_offset_;
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output_good_ = false;
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}
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}
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output_offset_ += byte_count;
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return true;
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}
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// This function always succeeds to simplify code.
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// Use Good() to check the actual status of the output stream.
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off_t Seek(off_t offset, Whence whence) override {
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// We keep shadow copy of the offset so that we return
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// the expected value even if the output stream failed.
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off_t new_offset;
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switch (whence) {
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case kSeekSet:
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new_offset = offset;
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break;
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case kSeekCurrent:
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new_offset = output_offset_ + offset;
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break;
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default:
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LOG(FATAL) << "Unsupported seek type: " << whence;
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UNREACHABLE();
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}
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if (output_good_) {
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off_t actual_offset = output_->Seek(offset, whence);
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if (actual_offset == static_cast<off_t>(-1)) {
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PLOG(ERROR) << "Failed to seek in " << GetLocation() << ". Offset=" << offset
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<< " whence=" << whence << " new_offset=" << new_offset;
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output_good_ = false;
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}
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DCHECK_EQ(actual_offset, new_offset);
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}
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output_offset_ = new_offset;
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return new_offset;
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}
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// Flush the output and return whether all operations have succeeded.
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// Do nothing if we already have a pending error.
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bool Flush() override {
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if (output_good_) {
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output_good_ = output_->Flush();
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}
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return output_good_;
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}
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// Check (without flushing) whether all operations have succeeded so far.
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bool Good() const {
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return output_good_;
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}
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private:
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OutputStream* output_;
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bool output_good_; // True if all writes to output succeeded.
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off_t output_offset_; // Keep track of the current position in the stream.
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};
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} // namespace art
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#endif // ART_LIBELFFILE_STREAM_ERROR_DELAYING_OUTPUT_STREAM_H_
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