zircon/system/ulib/blobfs/include/blobfs/compression/blob-compressor.h

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#pragma once

#ifndef __Fuchsia__
static_assert(false, "Fuchsia only header");
#endif

#include <optional>

#include <blobfs/compression/compressor.h>
#include <fbl/macros.h>
#include <fbl/unique_ptr.h>
#include <lib/fzl/owned-vmo-mapper.h>
#include <lz4/lz4frame.h>
#include <zircon/types.h>
#include <zstd/zstd.h>

namespace blobfs {

// A BlobCompressor is used to compress a blob transparently before it is written
// back to disk. This object owns the compression buffer, and abstracts away the
// differences between compression algorithms.
class BlobCompressor {
public:
    // Initializes a compression object given the requested |algorithm| and input |blob_size|.
    static std::optional<BlobCompressor> Create(CompressionAlgorithm algorithm, size_t blob_size);

    DISALLOW_COPY_AND_ASSIGN_ALLOW_MOVE(BlobCompressor);
    ~BlobCompressor();

    BlobCompressor(BlobCompressor&& o)
        : compressor_(std::move(o.compressor_)), compressed_blob_(std::move(o.compressed_blob_)) {}

    BlobCompressor& operator=(BlobCompressor&& o) {
        compressor_ = std::move(o.compressor_);
        compressed_blob_ = std::move(o.compressed_blob_);
        return *this;
    }

    size_t Size() const {
        return compressor_->Size();
    }

    zx_status_t Update(const void* input_data, size_t input_length) {
        return compressor_->Update(input_data, input_length);
    }

    zx_status_t End() {
        return compressor_->End();
    }

    // Returns a reference to a VMO containing the compressed blob.
    const zx::vmo& Vmo() const {
        return compressed_blob_.vmo();
    }
    // Returns a reference to the compression buffer.
    const void* Data() const {
        return compressed_blob_.start();
    }

private:
    BlobCompressor(fbl::unique_ptr<Compressor> compressor, fzl::OwnedVmoMapper compressed_blob);

    fbl::unique_ptr<Compressor> compressor_;
    fzl::OwnedVmoMapper compressed_blob_;
};

} // namespace blobfs