git.oblomov.eu Git - linux-2.6/blob - lib/lzo/lzo1x_decompress.c

   1 /*
   2  *  LZO1X Decompressor from MiniLZO
   3  *
   4  *  Copyright (C) 1996-2005 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 kernel use by:
  10  *  Nitin Gupta <nitingupta910@gmail.com>
  11  *  Richard Purdie <rpurdie@openedhand.com>
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/lzo.h>
  17 #include <asm/byteorder.h>
  18 #include <asm/unaligned.h>
  19 #include "lzodefs.h"
  20
  21 #define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x))
  22 #define HAVE_OP(x, op_end, op) ((size_t)(op_end - op) < (x))
  23 #define HAVE_LB(m_pos, out, op) (m_pos < out || m_pos >= op)
  24
  25 #define COPY4(dst, src) \
  26                 put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))
  27
  28 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
  29                         unsigned char *out, size_t *out_len)
  30 {
  31         const unsigned char * const ip_end = in + in_len;
  32         unsigned char * const op_end = out + *out_len;
  33         const unsigned char *ip = in, *m_pos;
  34         unsigned char *op = out;
  35         size_t t;
  36
  37         *out_len = 0;
  38
  39         if (*ip > 17) {
  40                 t = *ip++ - 17;
  41                 if (t < 4)
  42                         goto match_next;
  43                 if (HAVE_OP(t, op_end, op))
  44                         goto output_overrun;
  45                 if (HAVE_IP(t + 1, ip_end, ip))
  46                         goto input_overrun;
  47                 do {
  48                         *op++ = *ip++;
  49                 } while (--t > 0);
  50                 goto first_literal_run;
  51         }
  52
  53         while ((ip < ip_end)) {
  54                 t = *ip++;
  55                 if (t >= 16)
  56                         goto match;
  57                 if (t == 0) {
  58                         if (HAVE_IP(1, ip_end, ip))
  59                                 goto input_overrun;
  60                         while (*ip == 0) {
  61                                 t += 255;
  62                                 ip++;
  63                                 if (HAVE_IP(1, ip_end, ip))
  64                                         goto input_overrun;
  65                         }
  66                         t += 15 + *ip++;
  67                 }
  68                 if (HAVE_OP(t + 3, op_end, op))
  69                         goto output_overrun;
  70                 if (HAVE_IP(t + 4, ip_end, ip))
  71                         goto input_overrun;
  72
  73                 COPY4(op, ip);
  74                 op += 4;
  75                 ip += 4;
  76                 if (--t > 0) {
  77                         if (t >= 4) {
  78                                 do {
  79                                         COPY4(op, ip);
  80                                         op += 4;
  81                                         ip += 4;
  82                                         t -= 4;
  83                                 } while (t >= 4);
  84                                 if (t > 0) {
  85                                         do {
  86                                                 *op++ = *ip++;
  87                                         } while (--t > 0);
  88                                 }
  89                         } else {
  90                                 do {
  91                                         *op++ = *ip++;
  92                                 } while (--t > 0);
  93                         }
  94                 }
  95
  96 first_literal_run:
  97                 t = *ip++;
  98                 if (t >= 16)
  99                         goto match;
 100                 m_pos = op - (1 + M2_MAX_OFFSET);
 101                 m_pos -= t >> 2;
 102                 m_pos -= *ip++ << 2;
 103
 104                 if (HAVE_LB(m_pos, out, op))
 105                         goto lookbehind_overrun;
 106
 107                 if (HAVE_OP(3, op_end, op))
 108                         goto output_overrun;
 109                 *op++ = *m_pos++;
 110                 *op++ = *m_pos++;
 111                 *op++ = *m_pos;
 112
 113                 goto match_done;
 114
 115                 do {
 116 match:
 117                         if (t >= 64) {
 118                                 m_pos = op - 1;
 119                                 m_pos -= (t >> 2) & 7;
 120                                 m_pos -= *ip++ << 3;
 121                                 t = (t >> 5) - 1;
 122                                 if (HAVE_LB(m_pos, out, op))
 123                                         goto lookbehind_overrun;
 124                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 125                                         goto output_overrun;
 126                                 goto copy_match;
 127                         } else if (t >= 32) {
 128                                 t &= 31;
 129                                 if (t == 0) {
 130                                         if (HAVE_IP(1, ip_end, ip))
 131                                                 goto input_overrun;
 132                                         while (*ip == 0) {
 133                                                 t += 255;
 134                                                 ip++;
 135                                                 if (HAVE_IP(1, ip_end, ip))
 136                                                         goto input_overrun;
 137                                         }
 138                                         t += 31 + *ip++;
 139                                 }
 140                                 m_pos = op - 1;
 141                                 m_pos -= le16_to_cpu(get_unaligned(
 142                                         (const unsigned short *)ip)) >> 2;
 143                                 ip += 2;
 144                         } else if (t >= 16) {
 145                                 m_pos = op;
 146                                 m_pos -= (t & 8) << 11;
 147
 148                                 t &= 7;
 149                                 if (t == 0) {
 150                                         if (HAVE_IP(1, ip_end, ip))
 151                                                 goto input_overrun;
 152                                         while (*ip == 0) {
 153                                                 t += 255;
 154                                                 ip++;
 155                                                 if (HAVE_IP(1, ip_end, ip))
 156                                                         goto input_overrun;
 157                                         }
 158                                         t += 7 + *ip++;
 159                                 }
 160                                 m_pos -= le16_to_cpu(get_unaligned(
 161                                         (const unsigned short *)ip) >> 2);
 162                                 ip += 2;
 163                                 if (m_pos == op)
 164                                         goto eof_found;
 165                                 m_pos -= 0x4000;
 166                         } else {
 167                                 m_pos = op - 1;
 168                                 m_pos -= t >> 2;
 169                                 m_pos -= *ip++ << 2;
 170
 171                                 if (HAVE_LB(m_pos, out, op))
 172                                         goto lookbehind_overrun;
 173                                 if (HAVE_OP(2, op_end, op))
 174                                         goto output_overrun;
 175
 176                                 *op++ = *m_pos++;
 177                                 *op++ = *m_pos;
 178                                 goto match_done;
 179                         }
 180
 181                         if (HAVE_LB(m_pos, out, op))
 182                                 goto lookbehind_overrun;
 183                         if (HAVE_OP(t + 3 - 1, op_end, op))
 184                                 goto output_overrun;
 185
 186                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 187                                 COPY4(op, m_pos);
 188                                 op += 4;
 189                                 m_pos += 4;
 190                                 t -= 4 - (3 - 1);
 191                                 do {
 192                                         COPY4(op, m_pos);
 193                                         op += 4;
 194                                         m_pos += 4;
 195                                         t -= 4;
 196                                 } while (t >= 4);
 197                                 if (t > 0)
 198                                         do {
 199                                                 *op++ = *m_pos++;
 200                                         } while (--t > 0);
 201                         } else {
 202 copy_match:
 203                                 *op++ = *m_pos++;
 204                                 *op++ = *m_pos++;
 205                                 do {
 206                                         *op++ = *m_pos++;
 207                                 } while (--t > 0);
 208                         }
 209 match_done:
 210                         t = ip[-2] & 3;
 211                         if (t == 0)
 212                                 break;
 213 match_next:
 214                         if (HAVE_OP(t, op_end, op))
 215                                 goto output_overrun;
 216                         if (HAVE_IP(t + 1, ip_end, ip))
 217                                 goto input_overrun;
 218
 219                         *op++ = *ip++;
 220                         if (t > 1) {
 221                                 *op++ = *ip++;
 222                                 if (t > 2)
 223                                         *op++ = *ip++;
 224                         }
 225
 226                         t = *ip++;
 227                 } while (ip < ip_end);
 228         }
 229
 230         *out_len = op - out;
 231         return LZO_E_EOF_NOT_FOUND;
 232
 233 eof_found:
 234         *out_len = op - out;
 235         return (ip == ip_end ? LZO_E_OK :
 236                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 237 input_overrun:
 238         *out_len = op - out;
 239         return LZO_E_INPUT_OVERRUN;
 240
 241 output_overrun:
 242         *out_len = op - out;
 243         return LZO_E_OUTPUT_OVERRUN;
 244
 245 lookbehind_overrun:
 246         *out_len = op - out;
 247         return LZO_E_LOOKBEHIND_OVERRUN;
 248 }
 249
 250 EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
 251
 252 MODULE_LICENSE("GPL");
 253 MODULE_DESCRIPTION("LZO1X Decompressor");
 254