/usr/src/zfs-0.6.5.6/module/zfs/lzjb.c is in zfs-dkms 0.6.5.6-0ubuntu8.
This file is owned by root:root, with mode 0o644.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 | /*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
*/
/*
* We keep our own copy of this algorithm for 3 main reasons:
* 1. If we didn't, anyone modifying common/os/compress.c would
* directly break our on disk format
* 2. Our version of lzjb does not have a number of checks that the
* common/os version needs and uses
* 3. We initialize the lempel to ensure deterministic results,
* so that identical blocks can always be deduplicated.
* In particular, we are adding the "feature" that compress() can
* take a destination buffer size and returns the compressed length, or the
* source length if compression would overflow the destination buffer.
*/
#include <sys/zfs_context.h>
#define MATCH_BITS 6
#define MATCH_MIN 3
#define MATCH_MAX ((1 << MATCH_BITS) + (MATCH_MIN - 1))
#define OFFSET_MASK ((1 << (16 - MATCH_BITS)) - 1)
#define LEMPEL_SIZE 1024
/*ARGSUSED*/
size_t
lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
{
uchar_t *src = s_start;
uchar_t *dst = d_start;
uchar_t *cpy;
uchar_t *copymap = NULL;
int copymask = 1 << (NBBY - 1);
int mlen, offset, hash;
uint16_t *hp;
uint16_t *lempel;
lempel = kmem_zalloc(LEMPEL_SIZE * sizeof (uint16_t), KM_SLEEP);
while (src < (uchar_t *)s_start + s_len) {
if ((copymask <<= 1) == (1 << NBBY)) {
if (dst >= (uchar_t *)d_start + d_len - 1 - 2 * NBBY) {
kmem_free(lempel,
LEMPEL_SIZE*sizeof (uint16_t));
return (s_len);
}
copymask = 1;
copymap = dst;
*dst++ = 0;
}
if (src > (uchar_t *)s_start + s_len - MATCH_MAX) {
*dst++ = *src++;
continue;
}
hash = (src[0] << 16) + (src[1] << 8) + src[2];
hash += hash >> 9;
hash += hash >> 5;
hp = &lempel[hash & (LEMPEL_SIZE - 1)];
offset = (intptr_t)(src - *hp) & OFFSET_MASK;
*hp = (uint16_t)(uintptr_t)src;
cpy = src - offset;
if (cpy >= (uchar_t *)s_start && cpy != src &&
src[0] == cpy[0] && src[1] == cpy[1] && src[2] == cpy[2]) {
*copymap |= copymask;
for (mlen = MATCH_MIN; mlen < MATCH_MAX; mlen++)
if (src[mlen] != cpy[mlen])
break;
*dst++ = ((mlen - MATCH_MIN) << (NBBY - MATCH_BITS)) |
(offset >> NBBY);
*dst++ = (uchar_t)offset;
src += mlen;
} else {
*dst++ = *src++;
}
}
kmem_free(lempel, LEMPEL_SIZE * sizeof (uint16_t));
return (dst - (uchar_t *)d_start);
}
/*ARGSUSED*/
int
lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
{
uchar_t *src = s_start;
uchar_t *dst = d_start;
uchar_t *d_end = (uchar_t *)d_start + d_len;
uchar_t *cpy;
uchar_t copymap = 0;
int copymask = 1 << (NBBY - 1);
while (dst < d_end) {
if ((copymask <<= 1) == (1 << NBBY)) {
copymask = 1;
copymap = *src++;
}
if (copymap & copymask) {
int mlen = (src[0] >> (NBBY - MATCH_BITS)) + MATCH_MIN;
int offset = ((src[0] << NBBY) | src[1]) & OFFSET_MASK;
src += 2;
if ((cpy = dst - offset) < (uchar_t *)d_start)
return (-1);
while (--mlen >= 0 && dst < d_end)
*dst++ = *cpy++;
} else {
*dst++ = *src++;
}
}
return (0);
}
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