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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/public/cpp/system/file_stream_data_source.h"
#include <algorithm>
#include <limits>
#include "base/numerics/safe_conversions.h"
#include "mojo/public/cpp/system/file_data_source.h"
namespace mojo {
FileStreamDataSource::FileStreamDataSource(base::File file, int64_t length)
: file_(std::move(file)), length_(length) {}
FileStreamDataSource::~FileStreamDataSource() = default;
uint64_t FileStreamDataSource::GetLength() const {
return length_;
}
DataPipeProducer::DataSource::ReadResult FileStreamDataSource::Read(
uint64_t offset,
base::span<char> buffer) {
ReadResult result;
if (offset != current_offset_) {
result.result = MOJO_RESULT_INVALID_ARGUMENT;
return result;
}
uint64_t readable_size = length_ - offset;
uint64_t read_size =
std::min(uint64_t{std::numeric_limits<int>::max()},
std::min(uint64_t{buffer.size()}, readable_size));
std::optional<size_t> bytes_read =
file_.ReadAtCurrentPos(base::as_writable_bytes(buffer).first(
base::checked_cast<size_t>(read_size)));
if (!bytes_read.has_value()) {
result.bytes_read = 0;
result.result =
FileDataSource::ConvertFileErrorToMojoResult(file_.GetLastFileError());
} else {
result.bytes_read = bytes_read.value();
current_offset_ += bytes_read.value();
}
return result;
}
} // namespace mojo
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