50 lines
3.0 KiB
C
50 lines
3.0 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/nexgen32e/kompressor.h"
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#include "libc/nexgen32e/lz4.h"
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#include "libc/str/str.h"
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/**
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* Decompresses LZ4 file.
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*
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* We assume (1) the file is mmap()'d or was copied into into memory
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* beforehand; and (2) folks handling untrustworthy data shall place
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* 64kb of guard pages on the ends of each buffer, see mapanon(). We
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* don't intend to support XXHASH; we recommend folks needing checks
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* against data corruption consider crc32c(), or gzip since it's the
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* best at file recovery. Dictionaries are supported; by convention,
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* they are passed in the ≤64kb bytes preceding src.
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*
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* @return pointer to end of decoded data, similar to mempcpy()
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* @see mapanon(), lz4check()
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*/
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void *lz4decode(void *dest, const void *src) {
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const unsigned char *frame, *block;
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frame = (const unsigned char *)src;
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for (block = frame + LZ4_FRAME_HEADERSIZE(frame); !LZ4_BLOCK_ISEOF(block);
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block += LZ4_BLOCK_SIZE(frame, block)) {
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if (LZ4_BLOCK_ISCOMPRESSED(block)) {
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dest = lz4cpy(dest, LZ4_BLOCK_DATA(block), LZ4_BLOCK_DATASIZE(block));
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} else {
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dest = mempcpy(dest, LZ4_BLOCK_DATA(block), LZ4_BLOCK_DATASIZE(block));
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}
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}
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return dest;
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}
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