/*

 * Copyright (c) Meta Platforms, Inc. and affiliates.

 * All rights reserved.

 *

 * This source code is licensed under both the BSD-style license (found in the

 * LICENSE file in the root directory of this source tree) and the GPLv2 (found

 * in the COPYING file in the root directory of this source tree).

 * You may select, at your option, one of the above-listed licenses.

 */

#include "zstd.h"

#include "zstd_seekable.h"

#include "fuzz_helpers.h"

#include "fuzz_data_producer.h"

static ZSTD_seekable *stream = NULL;

static ZSTD_seekable_CStream *zscs = NULL;

static const size_t kSeekableOverheadSize = ZSTD_seekTableFooterSize;

int LLVMFuzzerTestOneInput(const uint8_t *src, size_t size)

{

    /* Give a random portion of src data to the producer, to use for

    parameter generation. The rest will be used for (de)compression */

    FUZZ_dataProducer_t *producer = FUZZ_dataProducer_create(src, size);

    size = FUZZ_dataProducer_reserveDataPrefix(producer);

    size_t const compressedBufferSize = ZSTD_compressBound(size) + kSeekableOverheadSize;

    uint8_t* compressedBuffer = (uint8_t*)malloc(compressedBufferSize);

    uint8_t* decompressedBuffer = (uint8_t*)malloc(size);

    int const cLevel = FUZZ_dataProducer_int32Range(producer, ZSTD_minCLevel(), ZSTD_maxCLevel());

    unsigned const checksumFlag = FUZZ_dataProducer_int32Range(producer, 0, 1);

    size_t const uncompressedSize = FUZZ_dataProducer_uint32Range(producer, 0, size);

    size_t const offset = FUZZ_dataProducer_uint32Range(producer, 0, size - uncompressedSize);

    size_t seekSize;

    if (!zscs) {

        zscs = ZSTD_seekable_createCStream();

        FUZZ_ASSERT(zscs);

    }

    if (!stream) {

        stream = ZSTD_seekable_create();

        FUZZ_ASSERT(stream);

    }

    {   /* Perform a compression */

        size_t const initStatus = ZSTD_seekable_initCStream(zscs, cLevel, checksumFlag, size);

        size_t endStatus;

        ZSTD_outBuffer out = { .dst=compressedBuffer, .pos=0, .size=compressedBufferSize };

        ZSTD_inBuffer  in  = { .src=src, .pos=0, .size=size };

        FUZZ_ASSERT(!ZSTD_isError(initStatus));

        do {

            size_t cSize = ZSTD_seekable_compressStream(zscs, &out, &in);

            FUZZ_ASSERT(!ZSTD_isError(cSize));

        } while (in.pos != in.size);

        FUZZ_ASSERT(in.pos == in.size);

        endStatus = ZSTD_seekable_endStream(zscs, &out);

        FUZZ_ASSERT(!ZSTD_isError(endStatus));

        seekSize = out.pos;

    }

    {   /* Decompress at an offset */

        size_t const initStatus = ZSTD_seekable_initBuff(stream, compressedBuffer, seekSize);

        size_t decompressedBytesTotal = 0;

        size_t dSize;

        FUZZ_ZASSERT(initStatus);

        do {

            dSize = ZSTD_seekable_decompress(stream, decompressedBuffer, uncompressedSize, offset);

            FUZZ_ASSERT(!ZSTD_isError(dSize));

            decompressedBytesTotal += dSize;

        } while (decompressedBytesTotal < uncompressedSize && dSize > 0);

        FUZZ_ASSERT(decompressedBytesTotal == uncompressedSize);

    }

    FUZZ_ASSERT_MSG(!FUZZ_memcmp(src+offset, decompressedBuffer, uncompressedSize), "Corruption!");

    free(decompressedBuffer);

    free(compressedBuffer);

    FUZZ_dataProducer_free(producer);

#ifndef STATEFUL_FUZZING

    ZSTD_seekable_free(stream); stream = NULL;

    ZSTD_seekable_freeCStream(zscs); zscs = NULL;

#endif

    return 0;

}