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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "chrome/browser/ash/file_system_provider/fileapi/buffering_file_stream_reader.h"
#include <algorithm>
#include <utility>
#include "base/functional/bind.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"
#include "storage/browser/file_system/file_system_backend.h"
namespace ash::file_system_provider {
BufferingFileStreamReader::BufferingFileStreamReader(
std::unique_ptr<storage::FileStreamReader> file_stream_reader,
int preloading_buffer_length,
int64_t max_bytes_to_read)
: file_stream_reader_(std::move(file_stream_reader)),
preloading_buffer_length_(preloading_buffer_length),
max_bytes_to_read_(max_bytes_to_read),
bytes_read_(0),
preloading_buffer_(base::MakeRefCounted<net::IOBufferWithSize>(
preloading_buffer_length)),
preloading_buffer_offset_(0),
preloaded_bytes_(0) {}
BufferingFileStreamReader::~BufferingFileStreamReader() = default;
int BufferingFileStreamReader::Read(net::IOBuffer* buffer,
int buffer_length,
net::CompletionOnceCallback callback) {
// Return as much as available in the internal buffer. It may be less than
// |buffer_length|, what is valid.
const int bytes_read =
CopyFromPreloadingBuffer(base::WrapRefCounted(buffer), buffer_length);
if (bytes_read)
return bytes_read;
// If the internal buffer is empty, and more bytes than the internal buffer
// size is requested, then call the internal file stream reader directly.
if (buffer_length >= preloading_buffer_length_) {
const int result = file_stream_reader_->Read(
buffer, buffer_length,
base::BindOnce(&BufferingFileStreamReader::OnReadCompleted,
weak_ptr_factory_.GetWeakPtr(), std::move(callback)));
DCHECK_EQ(result, net::ERR_IO_PENDING);
return result;
}
// Nothing copied, so contents have to be preloaded.
Preload(base::BindOnce(
&BufferingFileStreamReader::OnReadCompleted,
weak_ptr_factory_.GetWeakPtr(),
base::BindOnce(&BufferingFileStreamReader::OnPreloadCompleted,
weak_ptr_factory_.GetWeakPtr(),
base::WrapRefCounted(buffer), buffer_length,
std::move(callback))));
return net::ERR_IO_PENDING;
}
int64_t BufferingFileStreamReader::GetLength(
net::Int64CompletionOnceCallback callback) {
const int64_t result = file_stream_reader_->GetLength(std::move(callback));
DCHECK_EQ(net::ERR_IO_PENDING, result);
return result;
}
int BufferingFileStreamReader::CopyFromPreloadingBuffer(
scoped_refptr<net::IOBuffer> buffer,
int buffer_length) {
const int read_bytes = std::min(buffer_length, preloaded_bytes_);
memcpy(buffer->data(),
preloading_buffer_->data() + preloading_buffer_offset_,
read_bytes);
preloading_buffer_offset_ += read_bytes;
preloaded_bytes_ -= read_bytes;
return read_bytes;
}
void BufferingFileStreamReader::Preload(net::CompletionOnceCallback callback) {
const int preload_bytes =
std::min(static_cast<int64_t>(preloading_buffer_length_),
max_bytes_to_read_ - bytes_read_);
const int result = file_stream_reader_->Read(
preloading_buffer_.get(), preload_bytes, std::move(callback));
DCHECK_EQ(result, net::ERR_IO_PENDING);
}
void BufferingFileStreamReader::OnPreloadCompleted(
scoped_refptr<net::IOBuffer> buffer,
int buffer_length,
net::CompletionOnceCallback callback,
int result) {
if (result < 0) {
std::move(callback).Run(result);
return;
}
preloading_buffer_offset_ = 0;
preloaded_bytes_ = result;
std::move(callback).Run(CopyFromPreloadingBuffer(buffer, buffer_length));
}
void BufferingFileStreamReader::OnReadCompleted(
net::CompletionOnceCallback callback,
int result) {
if (result < 0) {
std::move(callback).Run(result);
return;
}
// If more bytes than declared in |max_bytes_to_read_| was read in total, then
// emit an
// error.
if (result > max_bytes_to_read_ - bytes_read_) {
std::move(callback).Run(net::ERR_FAILED);
return;
}
bytes_read_ += result;
DCHECK_LE(bytes_read_, max_bytes_to_read_);
std::move(callback).Run(result);
}
} // namespace ash::file_system_provider
|
