036b30b555
Super blocks must never violate the zstd block bound of input_size + ZSTD_blockHeaderSize. The individual sub-blocks may, but not the super block. If the superblock violates the block bound we are liable to violate ZSTD_compressBound(), which we must not do. Whenever the super block violates the block bound we instead emit an uncompressed block. This means we increase the latency because of the single uncompressed block. I fix this by enabling streaming an uncompressed block, so the latency of an uncompressed block is 1 byte. This doesn't reduce the latency of the buffer-less API, but I don't think we really care. * I added a test case that verifies that the decompression has 1 byte latency. * I rely on existing zstreamtest / fuzzer / libfuzzer regression tests for correctness. During development I had several correctness bugs, and they easily caught them. * The added assert that the superblock doesn't violate the block bound will help us discover any missed conditions (though I think I got them all). Credit to OSS-Fuzz.
32 lines
1.1 KiB
C
32 lines
1.1 KiB
C
/*
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* Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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#ifndef ZSTD_COMPRESS_ADVANCED_H
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#define ZSTD_COMPRESS_ADVANCED_H
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/*-*************************************
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* Dependencies
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***************************************/
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#include "zstd.h" /* ZSTD_CCtx */
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/*-*************************************
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* Target Compressed Block Size
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***************************************/
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/* ZSTD_compressSuperBlock() :
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* Used to compress a super block when targetCBlockSize is being used.
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* The given block will be compressed into multiple sub blocks that are around targetCBlockSize. */
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size_t ZSTD_compressSuperBlock(ZSTD_CCtx* zc,
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void* dst, size_t dstCapacity,
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unsigned lastBlock);
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#endif /* ZSTD_COMPRESS_ADVANCED_H */
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