daf181caa8
A negative return value doesn't make sense for any of those functions. The return types were inherited from POSIX, where they also need to have an indicator for an error (negative values).
79 lines
2.4 KiB
C++
79 lines
2.4 KiB
C++
/*
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* Copyright (c) 2021, kleines Filmröllchen <filmroellchen@serenityos.org>.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Error.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/OwnPtr.h>
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#include <AK/Span.h>
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#include <AK/TypedTransfer.h>
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#include <LibCore/Stream.h>
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namespace Core::Stream {
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/// A stream class that allows for reading/writing on a preallocated memory area
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/// using a single read/write head.
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class FixedMemoryStream final : public SeekableStream {
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public:
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static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(Bytes bytes);
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static ErrorOr<NonnullOwnPtr<FixedMemoryStream>> construct(ReadonlyBytes bytes);
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virtual bool is_eof() const override;
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virtual bool is_open() const override;
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virtual void close() override;
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virtual ErrorOr<void> truncate(off_t) override;
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virtual ErrorOr<Bytes> read(Bytes bytes) override;
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virtual ErrorOr<size_t> seek(i64 offset, SeekMode seek_mode = SeekMode::SetPosition) override;
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virtual ErrorOr<size_t> write(ReadonlyBytes bytes) override;
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virtual ErrorOr<void> write_entire_buffer(ReadonlyBytes bytes) override;
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Bytes bytes();
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ReadonlyBytes bytes() const;
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size_t offset() const;
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size_t remaining() const;
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private:
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explicit FixedMemoryStream(Bytes bytes);
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explicit FixedMemoryStream(ReadonlyBytes bytes);
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Bytes m_bytes;
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size_t m_offset { 0 };
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bool m_writing_enabled { true };
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};
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/// A stream class that allows for writing to an automatically allocating memory area
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/// and reading back the written data afterwards.
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class AllocatingMemoryStream final : public Stream {
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public:
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virtual ErrorOr<Bytes> read(Bytes) override;
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virtual ErrorOr<size_t> write(ReadonlyBytes) override;
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virtual ErrorOr<void> discard(size_t) override;
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virtual bool is_eof() const override;
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virtual bool is_open() const override;
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virtual void close() override;
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size_t used_buffer_size() const;
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ErrorOr<Optional<size_t>> offset_of(ReadonlyBytes needle) const;
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private:
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// Note: We set the inline buffer capacity to zero to make moving chunks as efficient as possible.
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using Chunk = AK::Detail::ByteBuffer<0>;
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static constexpr size_t chunk_size = 4096;
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ErrorOr<ReadonlyBytes> next_read_range();
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ErrorOr<Bytes> next_write_range();
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void cleanup_unused_chunks();
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Vector<Chunk> m_chunks;
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size_t m_read_offset = 0;
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size_t m_write_offset = 0;
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};
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}
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