lib/lzo: Update LZO compression to current upstream version
[linux-3.10.git] / lib / lzo / lzo1x_decompress_safe.c
1 /*
2  *  LZO1X Decompressor from LZO
3  *
4  *  Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
5  *
6  *  The full LZO package can be found at:
7  *  http://www.oberhumer.com/opensource/lzo/
8  *
9  *  Changed for Linux kernel use by:
10  *  Nitin Gupta <nitingupta910@gmail.com>
11  *  Richard Purdie <rpurdie@openedhand.com>
12  */
13
14 #ifndef STATIC
15 #include <linux/module.h>
16 #include <linux/kernel.h>
17 #endif
18 #include <asm/unaligned.h>
19 #include <linux/lzo.h>
20 #include "lzodefs.h"
21
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
27
28 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
29                           unsigned char *out, size_t *out_len)
30 {
31         unsigned char *op;
32         const unsigned char *ip;
33         size_t t, next;
34         size_t state = 0;
35         const unsigned char *m_pos;
36         const unsigned char * const ip_end = in + in_len;
37         unsigned char * const op_end = out + *out_len;
38
39         op = out;
40         ip = in;
41
42         if (unlikely(in_len < 3))
43                 goto input_overrun;
44         if (*ip > 17) {
45                 t = *ip++ - 17;
46                 if (t < 4) {
47                         next = t;
48                         goto match_next;
49                 }
50                 goto copy_literal_run;
51         }
52
53         for (;;) {
54                 t = *ip++;
55                 if (t < 16) {
56                         if (likely(state == 0)) {
57                                 if (unlikely(t == 0)) {
58                                         while (unlikely(*ip == 0)) {
59                                                 t += 255;
60                                                 ip++;
61                                                 NEED_IP(1);
62                                         }
63                                         t += 15 + *ip++;
64                                 }
65                                 t += 3;
66 copy_literal_run:
67 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
68                                 if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
69                                         const unsigned char *ie = ip + t;
70                                         unsigned char *oe = op + t;
71                                         do {
72                                                 COPY8(op, ip);
73                                                 op += 8;
74                                                 ip += 8;
75                                                 COPY8(op, ip);
76                                                 op += 8;
77                                                 ip += 8;
78                                         } while (ip < ie);
79                                         ip = ie;
80                                         op = oe;
81                                 } else
82 #endif
83                                 {
84                                         NEED_OP(t);
85                                         NEED_IP(t + 3);
86                                         do {
87                                                 *op++ = *ip++;
88                                         } while (--t > 0);
89                                 }
90                                 state = 4;
91                                 continue;
92                         } else if (state != 4) {
93                                 next = t & 3;
94                                 m_pos = op - 1;
95                                 m_pos -= t >> 2;
96                                 m_pos -= *ip++ << 2;
97                                 TEST_LB(m_pos);
98                                 NEED_OP(2);
99                                 op[0] = m_pos[0];
100                                 op[1] = m_pos[1];
101                                 op += 2;
102                                 goto match_next;
103                         } else {
104                                 next = t & 3;
105                                 m_pos = op - (1 + M2_MAX_OFFSET);
106                                 m_pos -= t >> 2;
107                                 m_pos -= *ip++ << 2;
108                                 t = 3;
109                         }
110                 } else if (t >= 64) {
111                         next = t & 3;
112                         m_pos = op - 1;
113                         m_pos -= (t >> 2) & 7;
114                         m_pos -= *ip++ << 3;
115                         t = (t >> 5) - 1 + (3 - 1);
116                 } else if (t >= 32) {
117                         t = (t & 31) + (3 - 1);
118                         if (unlikely(t == 2)) {
119                                 while (unlikely(*ip == 0)) {
120                                         t += 255;
121                                         ip++;
122                                         NEED_IP(1);
123                                 }
124                                 t += 31 + *ip++;
125                                 NEED_IP(2);
126                         }
127                         m_pos = op - 1;
128                         next = get_unaligned_le16(ip);
129                         ip += 2;
130                         m_pos -= next >> 2;
131                         next &= 3;
132                 } else {
133                         m_pos = op;
134                         m_pos -= (t & 8) << 11;
135                         t = (t & 7) + (3 - 1);
136                         if (unlikely(t == 2)) {
137                                 while (unlikely(*ip == 0)) {
138                                         t += 255;
139                                         ip++;
140                                         NEED_IP(1);
141                                 }
142                                 t += 7 + *ip++;
143                                 NEED_IP(2);
144                         }
145                         next = get_unaligned_le16(ip);
146                         ip += 2;
147                         m_pos -= next >> 2;
148                         next &= 3;
149                         if (m_pos == op)
150                                 goto eof_found;
151                         m_pos -= 0x4000;
152                 }
153                 TEST_LB(m_pos);
154 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
155                 if (op - m_pos >= 8) {
156                         unsigned char *oe = op + t;
157                         if (likely(HAVE_OP(t + 15))) {
158                                 do {
159                                         COPY8(op, m_pos);
160                                         op += 8;
161                                         m_pos += 8;
162                                         COPY8(op, m_pos);
163                                         op += 8;
164                                         m_pos += 8;
165                                 } while (op < oe);
166                                 op = oe;
167                                 if (HAVE_IP(6)) {
168                                         state = next;
169                                         COPY4(op, ip);
170                                         op += next;
171                                         ip += next;
172                                         continue;
173                                 }
174                         } else {
175                                 NEED_OP(t);
176                                 do {
177                                         *op++ = *m_pos++;
178                                 } while (op < oe);
179                         }
180                 } else
181 #endif
182                 {
183                         unsigned char *oe = op + t;
184                         NEED_OP(t);
185                         op[0] = m_pos[0];
186                         op[1] = m_pos[1];
187                         op += 2;
188                         m_pos += 2;
189                         do {
190                                 *op++ = *m_pos++;
191                         } while (op < oe);
192                 }
193 match_next:
194                 state = next;
195                 t = next;
196 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
197                 if (likely(HAVE_IP(6) && HAVE_OP(4))) {
198                         COPY4(op, ip);
199                         op += t;
200                         ip += t;
201                 } else
202 #endif
203                 {
204                         NEED_IP(t + 3);
205                         NEED_OP(t);
206                         while (t > 0) {
207                                 *op++ = *ip++;
208                                 t--;
209                         }
210                 }
211         }
212
213 eof_found:
214         *out_len = op - out;
215         return (t != 3       ? LZO_E_ERROR :
216                 ip == ip_end ? LZO_E_OK :
217                 ip <  ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
218
219 input_overrun:
220         *out_len = op - out;
221         return LZO_E_INPUT_OVERRUN;
222
223 output_overrun:
224         *out_len = op - out;
225         return LZO_E_OUTPUT_OVERRUN;
226
227 lookbehind_overrun:
228         *out_len = op - out;
229         return LZO_E_LOOKBEHIND_OVERRUN;
230 }
231 #ifndef STATIC
232 EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
233
234 MODULE_LICENSE("GPL");
235 MODULE_DESCRIPTION("LZO1X Decompressor");
236
237 #endif