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3983b80ca2
file_io and the FileReader family had a few loose ends regarding big reads and writes. It’s not likely that we’ve experienced these conditions yet, but they’d be likely to appear in a potential future involving full memory dumps. This specifies the behavior with large reads and writes, consolidates some logic, and improves some interfaces. ReadFile() should always return without retrying after a short read, and in fact does return after short reads since 00b64427523b. It is straightforward to limit the maximum read size based on a parameter limitation of the underlying operation, or a limitation of the type used for FileOperationResult. In contrast, WriteFile() should always retry after a short write, including a write shortened because of a parameter limitation of the underlying operation, or a limitation of the type used for FileOperationResult. This allows its return value to be simplified to a “bool”. The platform-specific WriteFile() code has been moved to internal::NativeWriteFile(), and the platform-independent loop that retries following a short write has been refactored into internal::WriteAllInternal so that it can be used by a new test. The platform-agnostic ReadFileExactlyInternal() implementation has been refactored into internal::ReadExactlyInternal so that it can be used by a new test and by FileReaderInterface::ReadExactly(), which had a nearly identical implementation. Test: crashpad_util_test FileIO.ReadExactly_*:FileIO.WriteAll_*:FileReader.ReadExactly_* Change-Id: I487450322ab049c6f2acd4061ea814037cc9a864 Reviewed-on: https://chromium-review.googlesource.com/456824 Reviewed-by: Scott Graham <scottmg@chromium.org>
112 lines
3.0 KiB
C++
112 lines
3.0 KiB
C++
// Copyright 2015 The Crashpad Authors. All rights reserved.
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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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#include "util/file/file_reader.h"
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#include "base/logging.h"
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#include "base/numerics/safe_conversions.h"
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#include "build/build_config.h"
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namespace crashpad {
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namespace {
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class FileReaderReadExactly final : public internal::ReadExactlyInternal {
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public:
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explicit FileReaderReadExactly(FileReaderInterface* file_reader)
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: ReadExactlyInternal(), file_reader_(file_reader) {}
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~FileReaderReadExactly() {}
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private:
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// ReadExactlyInternal:
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FileOperationResult Read(void* buffer, size_t size, bool can_log) override {
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DCHECK(can_log);
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return file_reader_->Read(buffer, size);
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}
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FileReaderInterface* file_reader_; // weak
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DISALLOW_COPY_AND_ASSIGN(FileReaderReadExactly);
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};
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} // namespace
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bool FileReaderInterface::ReadExactly(void* data, size_t size) {
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FileReaderReadExactly read_exactly(this);
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return read_exactly.ReadExactly(data, size, true);
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}
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WeakFileHandleFileReader::WeakFileHandleFileReader(FileHandle file_handle)
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: file_handle_(file_handle) {
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}
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WeakFileHandleFileReader::~WeakFileHandleFileReader() {
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}
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FileOperationResult WeakFileHandleFileReader::Read(void* data, size_t size) {
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DCHECK_NE(file_handle_, kInvalidFileHandle);
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base::checked_cast<FileOperationResult>(size);
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FileOperationResult rv = ReadFile(file_handle_, data, size);
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if (rv < 0) {
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PLOG(ERROR) << internal::kNativeReadFunctionName;
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return -1;
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}
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return rv;
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}
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FileOffset WeakFileHandleFileReader::Seek(FileOffset offset, int whence) {
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DCHECK_NE(file_handle_, kInvalidFileHandle);
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return LoggingSeekFile(file_handle_, offset, whence);
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}
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FileReader::FileReader()
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: file_(),
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weak_file_handle_file_reader_(kInvalidFileHandle) {
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}
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FileReader::~FileReader() {
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}
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bool FileReader::Open(const base::FilePath& path) {
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CHECK(!file_.is_valid());
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file_.reset(LoggingOpenFileForRead(path));
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if (!file_.is_valid()) {
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return false;
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}
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weak_file_handle_file_reader_.set_file_handle(file_.get());
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return true;
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}
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void FileReader::Close() {
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CHECK(file_.is_valid());
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weak_file_handle_file_reader_.set_file_handle(kInvalidFileHandle);
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file_.reset();
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}
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FileOperationResult FileReader::Read(void* data, size_t size) {
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DCHECK(file_.is_valid());
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return weak_file_handle_file_reader_.Read(data, size);
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}
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FileOffset FileReader::Seek(FileOffset offset, int whence) {
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DCHECK(file_.is_valid());
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return weak_file_handle_file_reader_.Seek(offset, whence);
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}
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} // namespace crashpad
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