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/*
* LZO1X Decompressor from LZO
*
* Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
*
* The full LZO package can be found at:
* http://www.oberhumer.com/opensource/lzo/
*
* Changed for Linux kernel use by:
* Nitin Gupta <nitingupta910@gmail.com>
* Richard Purdie <rpurdie@openedhand.com>
*/
#ifndef STATIC
#include <linux/module.h>
#include <linux/kernel.h>
#endif
#include <asm/unaligned.h>
#include <linux/lzo.h>
#include "lzodefs.h"
#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
#define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun
#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
* count without overflowing an integer. The multiply will overflow when
* multiplying 255 by more than MAXINT/255. The sum will overflow earlier
* depending on the base count. Since the base count is taken from a u8
* and a few bits, it is safe to assume that it will always be lower than
* or equal to 2*255, thus we can always prevent any overflow by accepting
* two less 255 steps. See Documentation/lzo.txt for more information.
*/
#define MAX_255_COUNT ((((size_t)~0) / 255) - 2)
int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
{
unsigned char *op;
const unsigned char *ip;
size_t t, next;
size_t state = 0;
const unsigned char *m_pos;
const unsigned char * const ip_end = in + in_len;
unsigned char * const op_end = out + *out_len;
op = out;
ip = in;
if (unlikely(in_len < 3))
goto input_overrun;
if (*ip > 17) {
t = *ip++ - 17;
if (t < 4) {
next = t;
goto match_next;
}
goto copy_literal_run;
}
for (;;) {
t = *ip++;
if (t < 16) {
if (likely(state == 0)) {
if (unlikely(t == 0)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip == 0)) {
ip++;
NEED_IP(1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset << 8) - offset;
t += offset + 15 + *ip++;
}
t += 3;
copy_literal_run:
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
const unsigned char *ie = ip + t;
unsigned char *oe = op + t;
do {
COPY8(op, ip);
op += 8;
ip += 8;
COPY8(op, ip);
op += 8;
ip += 8;
} while (ip < ie);
ip = ie;
op = oe;
} else
#endif
{
NEED_OP(t);
NEED_IP(t + 3);
do {
*op++ = *ip++;
} while (--t > 0);
}
state = 4;
continue;
} else if (state != 4) {
next = t & 3;
m_pos = op - 1;
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
TEST_LB(m_pos);
NEED_OP(2);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
goto match_next;
} else {
next = t & 3;
m_pos = op - (1 + M2_MAX_OFFSET);
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
t = 3;
}
} else if (t >= 64) {
next = t & 3;
m_pos = op - 1;
m_pos -= (t >> 2) & 7;
m_pos -= *ip++ << 3;
t = (t >> 5) - 1 + (3 - 1);
} else if (t >= 32) {
t = (t & 31) + (3 - 1);
if (unlikely(t == 2)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip == 0)) {
ip++;
NEED_IP(1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset << 8) - offset;
t += offset + 31 + *ip++;
NEED_IP(2);
}
m_pos = op - 1;
next = get_unaligned_le16(ip);
ip += 2;
m_pos -= next >> 2;
next &= 3;
} else {
m_pos = op;
m_pos -= (t & 8) << 11;
t = (t & 7) + (3 - 1);
if (unlikely(t == 2)) {
size_t offset;
const unsigned char *ip_last = ip;
while (unlikely(*ip == 0)) {
ip++;
NEED_IP(1);
}
offset = ip - ip_last;
if (unlikely(offset > MAX_255_COUNT))
return LZO_E_ERROR;
offset = (offset << 8) - offset;
t += offset + 7 + *ip++;
NEED_IP(2);
}
next = get_unaligned_le16(ip);
ip += 2;
m_pos -= next >> 2;
next &= 3;
if (m_pos == op)
goto eof_found;
m_pos -= 0x4000;
}
TEST_LB(m_pos);
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (op - m_pos >= 8) {
unsigned char *oe = op + t;
if (likely(HAVE_OP(t + 15))) {
do {
COPY8(op, m_pos);
op += 8;
m_pos += 8;
COPY8(op, m_pos);
op += 8;
m_pos += 8;
} while (op < oe);
op = oe;
if (HAVE_IP(6)) {
state = next;
COPY4(op, ip);
op += next;
ip += next;
continue;
}
} else {
NEED_OP(t);
do {
*op++ = *m_pos++;
} while (op < oe);
}
} else
#endif
{
unsigned char *oe = op + t;
NEED_OP(t);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
m_pos += 2;
do {
*op++ = *m_pos++;
} while (op < oe);
}
match_next:
state = next;
t = next;
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (likely(HAVE_IP(6) && HAVE_OP(4))) {
COPY4(op, ip);
op += t;
ip += t;
} else
#endif
{
NEED_IP(t + 3);
NEED_OP(t);
while (t > 0) {
*op++ = *ip++;
t--;
}
}
}
eof_found:
*out_len = op - out;
return (t != 3 ? LZO_E_ERROR :
ip == ip_end ? LZO_E_OK :
ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
input_overrun:
*out_len = op - out;
return LZO_E_INPUT_OVERRUN;
output_overrun:
*out_len = op - out;
return LZO_E_OUTPUT_OVERRUN;
lookbehind_overrun:
*out_len = op - out;
return LZO_E_LOOKBEHIND_OVERRUN;
}
#ifndef STATIC
EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LZO1X Decompressor");
#endif
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