lib_generic/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 <common.h>
  15 #include <linux/lzo.h>
  16 #include <asm/byteorder.h>
  17 #include <asm/unaligned.h>
  18 #include "lzodefs.h"
  19
  20 #define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x))
  21 #define HAVE_OP(x, op_end, op) ((size_t)(op_end - op) < (x))
  22 #define HAVE_LB(m_pos, out, op) (m_pos < out || m_pos >= op)
  23
  24 #define COPY4(dst, src) \
  25                 put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))
  26
  27 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
  28                         unsigned char *out, size_t *out_len)
  29 {
  30         const unsigned char * const ip_end = in + in_len;
  31         unsigned char * const op_end = out + *out_len;
  32         const unsigned char *ip = in, *m_pos;
  33         unsigned char *op = out;
  34         size_t t;
  35
  36         *out_len = 0;
  37
  38         if (*ip > 17) {
  39                 t = *ip++ - 17;
  40                 if (t < 4)
  41                         goto match_next;
  42                 if (HAVE_OP(t, op_end, op))
  43                         goto output_overrun;
  44                 if (HAVE_IP(t + 1, ip_end, ip))
  45                         goto input_overrun;
  46                 do {
  47                         *op++ = *ip++;
  48                 } while (--t > 0);
  49                 goto first_literal_run;
  50         }
  51
  52         while ((ip < ip_end)) {
  53                 t = *ip++;
  54                 if (t >= 16)
  55                         goto match;
  56                 if (t == 0) {
  57                         if (HAVE_IP(1, ip_end, ip))
  58                                 goto input_overrun;
  59                         while (*ip == 0) {
  60                                 t += 255;
  61                                 ip++;
  62                                 if (HAVE_IP(1, ip_end, ip))
  63                                         goto input_overrun;
  64                         }
  65                         t += 15 + *ip++;
  66                 }
  67                 if (HAVE_OP(t + 3, op_end, op))
  68                         goto output_overrun;
  69                 if (HAVE_IP(t + 4, ip_end, ip))
  70                         goto input_overrun;
  71
  72                 COPY4(op, ip);
  73                 op += 4;
  74                 ip += 4;
  75                 if (--t > 0) {
  76                         if (t >= 4) {
  77                                 do {
  78                                         COPY4(op, ip);
  79                                         op += 4;
  80                                         ip += 4;
  81                                         t -= 4;
  82                                 } while (t >= 4);
  83                                 if (t > 0) {
  84                                         do {
  85                                                 *op++ = *ip++;
  86                                         } while (--t > 0);
  87                                 }
  88                         } else {
  89                                 do {
  90                                         *op++ = *ip++;
  91                                 } while (--t > 0);
  92                         }
  93                 }
  94
  95 first_literal_run:
  96                 t = *ip++;
  97                 if (t >= 16)
  98                         goto match;
  99                 m_pos = op - (1 + M2_MAX_OFFSET);
 100                 m_pos -= t >> 2;
 101                 m_pos -= *ip++ << 2;
 102
 103                 if (HAVE_LB(m_pos, out, op))
 104                         goto lookbehind_overrun;
 105
 106                 if (HAVE_OP(3, op_end, op))
 107                         goto output_overrun;
 108                 *op++ = *m_pos++;
 109                 *op++ = *m_pos++;
 110                 *op++ = *m_pos;
 111
 112                 goto match_done;
 113
 114                 do {
 115 match:
 116                         if (t >= 64) {
 117                                 m_pos = op - 1;
 118                                 m_pos -= (t >> 2) & 7;
 119                                 m_pos -= *ip++ << 3;
 120                                 t = (t >> 5) - 1;
 121                                 if (HAVE_LB(m_pos, out, op))
 122                                         goto lookbehind_overrun;
 123                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 124                                         goto output_overrun;
 125                                 goto copy_match;
 126                         } else if (t >= 32) {
 127                                 t &= 31;
 128                                 if (t == 0) {
 129                                         if (HAVE_IP(1, ip_end, ip))
 130                                                 goto input_overrun;
 131                                         while (*ip == 0) {
 132                                                 t += 255;
 133                                                 ip++;
 134                                                 if (HAVE_IP(1, ip_end, ip))
 135                                                         goto input_overrun;
 136                                         }
 137                                         t += 31 + *ip++;
 138                                 }
 139                                 m_pos = op - 1;
 140                                 m_pos -= get_unaligned_le16(ip) >> 2;
 141                                 ip += 2;
 142                         } else if (t >= 16) {
 143                                 m_pos = op;
 144                                 m_pos -= (t & 8) << 11;
 145
 146                                 t &= 7;
 147                                 if (t == 0) {
 148                                         if (HAVE_IP(1, ip_end, ip))
 149                                                 goto input_overrun;
 150                                         while (*ip == 0) {
 151                                                 t += 255;
 152                                                 ip++;
 153                                                 if (HAVE_IP(1, ip_end, ip))
 154                                                         goto input_overrun;
 155                                         }
 156                                         t += 7 + *ip++;
 157                                 }
 158                                 m_pos -= get_unaligned_le16(ip) >> 2;
 159                                 ip += 2;
 160                                 if (m_pos == op)
 161                                         goto eof_found;
 162                                 m_pos -= 0x4000;
 163                         } else {
 164                                 m_pos = op - 1;
 165                                 m_pos -= t >> 2;
 166                                 m_pos -= *ip++ << 2;
 167
 168                                 if (HAVE_LB(m_pos, out, op))
 169                                         goto lookbehind_overrun;
 170                                 if (HAVE_OP(2, op_end, op))
 171                                         goto output_overrun;
 172
 173                                 *op++ = *m_pos++;
 174                                 *op++ = *m_pos;
 175                                 goto match_done;
 176                         }
 177
 178                         if (HAVE_LB(m_pos, out, op))
 179                                 goto lookbehind_overrun;
 180                         if (HAVE_OP(t + 3 - 1, op_end, op))
 181                                 goto output_overrun;
 182
 183                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 184                                 COPY4(op, m_pos);
 185                                 op += 4;
 186                                 m_pos += 4;
 187                                 t -= 4 - (3 - 1);
 188                                 do {
 189                                         COPY4(op, m_pos);
 190                                         op += 4;
 191                                         m_pos += 4;
 192                                         t -= 4;
 193                                 } while (t >= 4);
 194                                 if (t > 0)
 195                                         do {
 196                                                 *op++ = *m_pos++;
 197                                         } while (--t > 0);
 198                         } else {
 199 copy_match:
 200                                 *op++ = *m_pos++;
 201                                 *op++ = *m_pos++;
 202                                 do {
 203                                         *op++ = *m_pos++;
 204                                 } while (--t > 0);
 205                         }
 206 match_done:
 207                         t = ip[-2] & 3;
 208                         if (t == 0)
 209                                 break;
 210 match_next:
 211                         if (HAVE_OP(t, op_end, op))
 212                                 goto output_overrun;
 213                         if (HAVE_IP(t + 1, ip_end, ip))
 214                                 goto input_overrun;
 215
 216                         *op++ = *ip++;
 217                         if (t > 1) {
 218                                 *op++ = *ip++;
 219                                 if (t > 2)
 220                                         *op++ = *ip++;
 221                         }
 222
 223                         t = *ip++;
 224                 } while (ip < ip_end);
 225         }
 226
 227         *out_len = op - out;
 228         return LZO_E_EOF_NOT_FOUND;
 229
 230 eof_found:
 231         *out_len = op - out;
 232         return (ip == ip_end ? LZO_E_OK :
 233                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 234 input_overrun:
 235         *out_len = op - out;
 236         return LZO_E_INPUT_OVERRUN;
 237
 238 output_overrun:
 239         *out_len = op - out;
 240         return LZO_E_OUTPUT_OVERRUN;
 241
 242 lookbehind_overrun:
 243         *out_len = op - out;
 244         return LZO_E_LOOKBEHIND_OVERRUN;
 245 }