51 lines
3.0 KiB
C
51 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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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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