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Linux/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
238 

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