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276 lines
7.1 KiB
C++
276 lines
7.1 KiB
C++
/*
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* Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
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* Copyright (c) 2022, Tim Schumacher <timschumi@gmx.de>.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/ByteBuffer.h>
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#include <AK/FixedArray.h>
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#include <AK/MemMem.h>
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#include <AK/MemoryStream.h>
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namespace AK {
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FixedMemoryStream::FixedMemoryStream(Bytes bytes)
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: m_bytes(bytes)
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{
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}
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FixedMemoryStream::FixedMemoryStream(ReadonlyBytes bytes)
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: m_bytes({ const_cast<u8*>(bytes.data()), bytes.size() })
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, m_writing_enabled(false)
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{
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}
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ErrorOr<NonnullOwnPtr<FixedMemoryStream>> FixedMemoryStream::construct(Bytes bytes)
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{
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return adopt_nonnull_own_or_enomem<FixedMemoryStream>(new (nothrow) FixedMemoryStream(bytes));
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}
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ErrorOr<NonnullOwnPtr<FixedMemoryStream>> FixedMemoryStream::construct(ReadonlyBytes bytes)
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{
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return adopt_nonnull_own_or_enomem<FixedMemoryStream>(new (nothrow) FixedMemoryStream(bytes));
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}
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bool FixedMemoryStream::is_eof() const
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{
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return m_offset >= m_bytes.size();
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}
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bool FixedMemoryStream::is_open() const
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{
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return true;
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}
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void FixedMemoryStream::close()
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{
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// FIXME: It doesn't make sense to close a memory stream. Therefore, we don't do anything here. Is that fine?
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}
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ErrorOr<void> FixedMemoryStream::truncate(off_t)
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{
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return Error::from_errno(EBADF);
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}
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ErrorOr<Bytes> FixedMemoryStream::read(Bytes bytes)
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{
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auto to_read = min(remaining(), bytes.size());
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if (to_read == 0)
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return Bytes {};
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m_bytes.slice(m_offset, to_read).copy_to(bytes);
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m_offset += to_read;
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return bytes.trim(to_read);
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}
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ErrorOr<size_t> FixedMemoryStream::seek(i64 offset, SeekMode seek_mode)
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{
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switch (seek_mode) {
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case SeekMode::SetPosition:
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if (offset > static_cast<i64>(m_bytes.size()))
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return Error::from_string_literal("Offset past the end of the stream memory");
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m_offset = offset;
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break;
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case SeekMode::FromCurrentPosition:
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if (offset + static_cast<i64>(m_offset) > static_cast<i64>(m_bytes.size()))
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return Error::from_string_literal("Offset past the end of the stream memory");
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m_offset += offset;
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break;
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case SeekMode::FromEndPosition:
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if (offset > static_cast<i64>(m_bytes.size()))
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return Error::from_string_literal("Offset past the start of the stream memory");
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m_offset = m_bytes.size() - offset;
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break;
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}
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return m_offset;
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}
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ErrorOr<size_t> FixedMemoryStream::write(ReadonlyBytes bytes)
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{
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VERIFY(m_writing_enabled);
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// FIXME: Can this not error?
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auto const nwritten = bytes.copy_trimmed_to(m_bytes.slice(m_offset));
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m_offset += nwritten;
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return nwritten;
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}
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ErrorOr<void> FixedMemoryStream::write_entire_buffer(ReadonlyBytes bytes)
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{
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if (remaining() < bytes.size())
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return Error::from_string_literal("Write of entire buffer ends past the memory area");
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TRY(write(bytes));
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return {};
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}
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Bytes FixedMemoryStream::bytes()
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{
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VERIFY(m_writing_enabled);
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return m_bytes;
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}
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ReadonlyBytes FixedMemoryStream::bytes() const
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{
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return m_bytes;
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}
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size_t FixedMemoryStream::offset() const
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{
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return m_offset;
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}
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size_t FixedMemoryStream::remaining() const
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{
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return m_bytes.size() - m_offset;
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}
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ErrorOr<Bytes> AllocatingMemoryStream::read(Bytes bytes)
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{
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size_t read_bytes = 0;
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while (read_bytes < bytes.size()) {
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VERIFY(m_write_offset >= m_read_offset);
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auto range = TRY(next_read_range());
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if (range.size() == 0)
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break;
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auto copied_bytes = range.copy_trimmed_to(bytes.slice(read_bytes));
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read_bytes += copied_bytes;
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m_read_offset += copied_bytes;
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}
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cleanup_unused_chunks();
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return bytes.trim(read_bytes);
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}
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ErrorOr<size_t> AllocatingMemoryStream::write(ReadonlyBytes bytes)
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{
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size_t written_bytes = 0;
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while (written_bytes < bytes.size()) {
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VERIFY(m_write_offset >= m_read_offset);
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auto range = TRY(next_write_range());
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auto copied_bytes = bytes.slice(written_bytes).copy_trimmed_to(range);
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written_bytes += copied_bytes;
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m_write_offset += copied_bytes;
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}
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return written_bytes;
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}
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ErrorOr<void> AllocatingMemoryStream::discard(size_t count)
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{
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VERIFY(m_write_offset >= m_read_offset);
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if (count > used_buffer_size())
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return Error::from_string_literal("Number of discarded bytes is higher than the number of allocated bytes");
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m_read_offset += count;
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cleanup_unused_chunks();
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return {};
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}
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bool AllocatingMemoryStream::is_eof() const
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{
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return used_buffer_size() == 0;
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}
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bool AllocatingMemoryStream::is_open() const
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{
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return true;
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}
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void AllocatingMemoryStream::close()
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{
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}
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size_t AllocatingMemoryStream::used_buffer_size() const
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{
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return m_write_offset - m_read_offset;
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}
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ErrorOr<Optional<size_t>> AllocatingMemoryStream::offset_of(ReadonlyBytes needle) const
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{
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VERIFY(m_write_offset >= m_read_offset);
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if (m_chunks.size() == 0)
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return Optional<size_t> {};
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// Ensure that we don't have to trim away more than one block.
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VERIFY(m_read_offset < chunk_size);
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VERIFY(m_chunks.size() * chunk_size - m_write_offset < chunk_size);
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auto chunk_count = m_chunks.size();
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auto search_spans = TRY(FixedArray<ReadonlyBytes>::create(chunk_count));
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for (size_t i = 0; i < chunk_count; i++) {
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search_spans[i] = m_chunks[i].span();
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}
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// Trimming is done first to ensure that we don't unintentionally shift around if the first and last chunks are the same.
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search_spans[chunk_count - 1] = search_spans[chunk_count - 1].trim(m_write_offset % chunk_size);
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search_spans[0] = search_spans[0].slice(m_read_offset);
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return AK::memmem(search_spans.begin(), search_spans.end(), needle);
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}
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ErrorOr<ReadonlyBytes> AllocatingMemoryStream::next_read_range()
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{
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VERIFY(m_write_offset >= m_read_offset);
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size_t const chunk_index = m_read_offset / chunk_size;
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size_t const chunk_offset = m_read_offset % chunk_size;
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size_t const read_size = min(chunk_size - m_read_offset % chunk_size, m_write_offset - m_read_offset);
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if (read_size == 0)
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return ReadonlyBytes { static_cast<u8*>(nullptr), 0 };
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VERIFY(chunk_index < m_chunks.size());
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return ReadonlyBytes { m_chunks[chunk_index].data() + chunk_offset, read_size };
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}
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ErrorOr<Bytes> AllocatingMemoryStream::next_write_range()
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{
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VERIFY(m_write_offset >= m_read_offset);
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size_t const chunk_index = m_write_offset / chunk_size;
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size_t const chunk_offset = m_write_offset % chunk_size;
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size_t const write_size = chunk_size - m_write_offset % chunk_size;
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if (chunk_index >= m_chunks.size())
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TRY(m_chunks.try_append(TRY(Chunk::create_uninitialized(chunk_size))));
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VERIFY(chunk_index < m_chunks.size());
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return Bytes { m_chunks[chunk_index].data() + chunk_offset, write_size };
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}
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void AllocatingMemoryStream::cleanup_unused_chunks()
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{
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// FIXME: Move these all at once.
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while (m_read_offset >= chunk_size) {
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VERIFY(m_write_offset >= m_read_offset);
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auto buffer = m_chunks.take_first();
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m_read_offset -= chunk_size;
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m_write_offset -= chunk_size;
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m_chunks.append(move(buffer));
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}
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}
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}
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