2 * LZO1X Decompressor from LZO
4 * Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
6 * The full LZO package can be found at:
7 * http://www.oberhumer.com/opensource/lzo/
9 * Changed for Linux kernel use by:
10 * Nitin Gupta <nitingupta910@gmail.com>
11 * Richard Purdie <rpurdie@openedhand.com>
15 #include <linux/module.h>
16 #include <linux/kernel.h>
18 #include <asm/unaligned.h>
19 #include <linux/lzo.h>
22 #define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
23 #define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
24 #define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun
25 #define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
26 #define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
28 /* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
29 * count without overflowing an integer. The multiply will overflow when
30 * multiplying 255 by more than MAXINT/255. The sum will overflow earlier
31 * depending on the base count. Since the base count is taken from a u8
32 * and a few bits, it is safe to assume that it will always be lower than
33 * or equal to 2*255, thus we can always prevent any overflow by accepting
34 * two less 255 steps. See Documentation/lzo.txt for more information.
36 #define MAX_255_COUNT ((((size_t)~0) / 255) - 2)
38 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
39 unsigned char *out, size_t *out_len)
42 const unsigned char *ip;
45 const unsigned char *m_pos;
46 const unsigned char * const ip_end = in + in_len;
47 unsigned char * const op_end = out + *out_len;
49 unsigned char bitstream_version;
54 if (unlikely(in_len < 3))
57 if (likely(in_len >= 5) && likely(*ip == 17)) {
58 bitstream_version = ip[1];
61 bitstream_version = 0;
70 goto copy_literal_run;
76 if (likely(state == 0)) {
77 if (unlikely(t == 0)) {
79 const unsigned char *ip_last = ip;
81 while (unlikely(*ip == 0)) {
85 offset = ip - ip_last;
86 if (unlikely(offset > MAX_255_COUNT))
89 offset = (offset << 8) - offset;
90 t += offset + 15 + *ip++;
94 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
95 if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
96 const unsigned char *ie = ip + t;
97 unsigned char *oe = op + t;
119 } else if (state != 4) {
132 m_pos = op - (1 + M2_MAX_OFFSET);
137 } else if (t >= 64) {
140 m_pos -= (t >> 2) & 7;
142 t = (t >> 5) - 1 + (3 - 1);
143 } else if (t >= 32) {
144 t = (t & 31) + (3 - 1);
145 if (unlikely(t == 2)) {
147 const unsigned char *ip_last = ip;
149 while (unlikely(*ip == 0)) {
153 offset = ip - ip_last;
154 if (unlikely(offset > MAX_255_COUNT))
157 offset = (offset << 8) - offset;
158 t += offset + 31 + *ip++;
162 next = get_unaligned_le16(ip);
168 next = get_unaligned_le16(ip);
169 if (((next & 0xfffc) == 0xfffc) &&
170 ((t & 0xf8) == 0x18) &&
171 likely(bitstream_version)) {
175 t += MIN_ZERO_RUN_LENGTH;
184 m_pos -= (t & 8) << 11;
185 t = (t & 7) + (3 - 1);
186 if (unlikely(t == 2)) {
188 const unsigned char *ip_last = ip;
190 while (unlikely(*ip == 0)) {
194 offset = ip - ip_last;
195 if (unlikely(offset > MAX_255_COUNT))
198 offset = (offset << 8) - offset;
199 t += offset + 7 + *ip++;
201 next = get_unaligned_le16(ip);
212 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
213 if (op - m_pos >= 8) {
214 unsigned char *oe = op + t;
215 if (likely(HAVE_OP(t + 15))) {
241 unsigned char *oe = op + t;
254 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
255 if (likely(HAVE_IP(6) && HAVE_OP(4))) {
273 return (t != 3 ? LZO_E_ERROR :
274 ip == ip_end ? LZO_E_OK :
275 ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
279 return LZO_E_INPUT_OVERRUN;
283 return LZO_E_OUTPUT_OVERRUN;
287 return LZO_E_LOOKBEHIND_OVERRUN;
290 EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
292 MODULE_LICENSE("GPL");
293 MODULE_DESCRIPTION("LZO1X Decompressor");