ladybird/AK/Stream.cpp

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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ByteBuffer.h>
#include <AK/Format.h>
#include <AK/Stream.h>
namespace AK {
ErrorOr<void> Stream::read_until_filled(Bytes buffer)
{
size_t nread = 0;
while (nread < buffer.size()) {
if (is_eof())
return Error::from_string_view_or_print_error_and_return_errno("Reached end-of-file before filling the entire buffer"sv, EIO);
auto result = read_some(buffer.slice(nread));
if (result.is_error()) {
if (result.error().is_errno() && result.error().code() == EINTR) {
continue;
}
return result.release_error();
}
nread += result.value().size();
}
return {};
}
ErrorOr<ByteBuffer> Stream::read_until_eof(size_t block_size)
{
return read_until_eof_impl(block_size);
}
ErrorOr<ByteBuffer> Stream::read_until_eof_impl(size_t block_size, size_t expected_file_size)
{
ByteBuffer data;
data.ensure_capacity(expected_file_size);
size_t total_read = 0;
Bytes buffer;
while (!is_eof()) {
if (buffer.is_empty()) {
buffer = TRY(data.get_bytes_for_writing(block_size));
}
auto nread = TRY(read_some(buffer)).size();
total_read += nread;
buffer = buffer.slice(nread);
}
data.resize(total_read);
return data;
}
ErrorOr<void> Stream::discard(size_t discarded_bytes)
{
// Note: This was chosen arbitrarily.
// Note: This can't be PAGE_SIZE because it is defined to sysconf() on Lagom.
constexpr size_t continuous_read_size = 4096;
Array<u8, continuous_read_size> buffer;
while (discarded_bytes > 0) {
if (is_eof())
return Error::from_string_view_or_print_error_and_return_errno("Reached end-of-file before reading all discarded bytes"sv, EIO);
auto slice = TRY(read_some(buffer.span().slice(0, min(discarded_bytes, continuous_read_size))));
discarded_bytes -= slice.size();
}
return {};
}
ErrorOr<void> Stream::write_until_depleted(ReadonlyBytes buffer)
{
size_t nwritten = 0;
while (nwritten < buffer.size()) {
auto result = write_some(buffer.slice(nwritten));
if (result.is_error()) {
if (result.error().is_errno() && result.error().code() == EINTR) {
continue;
}
return result.release_error();
}
nwritten += result.value();
}
return {};
}
ErrorOr<size_t> SeekableStream::tell() const
{
// Seek with 0 and SEEK_CUR does not modify anything despite the const_cast,
// so it's safe to do this.
return const_cast<SeekableStream*>(this)->seek(0, SeekMode::FromCurrentPosition);
}
ErrorOr<size_t> SeekableStream::size()
{
auto original_position = TRY(tell());
auto seek_result = seek(0, SeekMode::FromEndPosition);
if (seek_result.is_error()) {
// Let's try to restore the original position, just in case.
auto restore_result = seek(original_position, SeekMode::SetPosition);
if (restore_result.is_error()) {
dbgln("SeekableStream::size: Couldn't restore initial position, stream might have incorrect position now!");
}
return seek_result.release_error();
}
TRY(seek(original_position, SeekMode::SetPosition));
return seek_result.value();
}
ErrorOr<void> SeekableStream::discard(size_t discarded_bytes)
{
TRY(seek(discarded_bytes, SeekMode::FromCurrentPosition));
return {};
}
}