util/file/file_reader.cc

// Copyright 2015 The Crashpad Authors. All rights reserved.
//
// 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 "util/file/file_reader.h"

#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "build/build_config.h"

namespace crashpad {

namespace {

class FileReaderReadExactly final : public internal::ReadExactlyInternal {
 public:
  explicit FileReaderReadExactly(FileReaderInterface* file_reader)
      : ReadExactlyInternal(), file_reader_(file_reader) {}
  ~FileReaderReadExactly() {}

 private:
  // ReadExactlyInternal:
  FileOperationResult Read(void* buffer, size_t size, bool can_log) override {
    DCHECK(can_log);
    return file_reader_->Read(buffer, size);
  }

  FileReaderInterface* file_reader_;  // weak

  DISALLOW_COPY_AND_ASSIGN(FileReaderReadExactly);
};

}  // namespace

bool FileReaderInterface::ReadExactly(void* data, size_t size) {
  FileReaderReadExactly read_exactly(this);
  return read_exactly.ReadExactly(data, size, true);
}

WeakFileHandleFileReader::WeakFileHandleFileReader(FileHandle file_handle)
    : file_handle_(file_handle) {
}

WeakFileHandleFileReader::~WeakFileHandleFileReader() {
}

FileOperationResult WeakFileHandleFileReader::Read(void* data, size_t size) {
  DCHECK_NE(file_handle_, kInvalidFileHandle);

  base::checked_cast<FileOperationResult>(size);
  FileOperationResult rv = ReadFile(file_handle_, data, size);
  if (rv < 0) {
    PLOG(ERROR) << internal::kNativeReadFunctionName;
    return -1;
  }

  return rv;
}

FileOffset WeakFileHandleFileReader::Seek(FileOffset offset, int whence) {
  DCHECK_NE(file_handle_, kInvalidFileHandle);
  return LoggingSeekFile(file_handle_, offset, whence);
}

FileReader::FileReader()
    : file_(),
      weak_file_handle_file_reader_(kInvalidFileHandle) {
}

FileReader::~FileReader() {
}

bool FileReader::Open(const base::FilePath& path) {
  CHECK(!file_.is_valid());
  file_.reset(LoggingOpenFileForRead(path));
  if (!file_.is_valid()) {
    return false;
  }

  weak_file_handle_file_reader_.set_file_handle(file_.get());
  return true;
}

void FileReader::Close() {
  CHECK(file_.is_valid());

  weak_file_handle_file_reader_.set_file_handle(kInvalidFileHandle);
  file_.reset();
}

FileOperationResult FileReader::Read(void* data, size_t size) {
  DCHECK(file_.is_valid());
  return weak_file_handle_file_reader_.Read(data, size);
}

FileOffset FileReader::Seek(FileOffset offset, int whence) {
  DCHECK(file_.is_valid());
  return weak_file_handle_file_reader_.Seek(offset, whence);
}

}  // namespace crashpad