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 <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 static const unsigned char lzop_magic[] = {
  28         0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a
  29 };
  30
  31 #define HEADER_HAS_FILTER       0x00000800L
  32
  33 static inline const unsigned char *parse_header(const unsigned char *src)
  34 {
  35         u16 version;
  36         int i;
  37
  38         /* read magic: 9 first bytes */
  39         for (i = 0; i < ARRAY_SIZE(lzop_magic); i++) {
  40                 if (*src++ != lzop_magic[i])
  41                         return NULL;
  42         }
  43         /* get version (2bytes), skip library version (2),
  44          * 'need to be extracted' version (2) and
  45          * method (1) */
  46         version = get_unaligned_be16(src);
  47         src += 7;
  48         if (version >= 0x0940)
  49                 src++;
  50         if (get_unaligned_be32(src) & HEADER_HAS_FILTER)
  51                 src += 4; /* filter info */
  52
  53         /* skip flags, mode and mtime_low */
  54         src += 12;
  55         if (version >= 0x0940)
  56                 src += 4;       /* skip mtime_high */
  57
  58         i = *src++;
  59         /* don't care about the file name, and skip checksum */
  60         src += i + 4;
  61
  62         return src;
  63 }
  64
  65 int lzop_decompress(const unsigned char *src, size_t src_len,
  66                     unsigned char *dst, size_t *dst_len)
  67 {
  68         unsigned char *start = dst;
  69         const unsigned char *send = src + src_len;
  70         u32 slen, dlen;
  71         size_t tmp, remaining;
  72         int r;
  73
  74         src = parse_header(src);
  75         if (!src)
  76                 return LZO_E_ERROR;
  77
  78         remaining = *dst_len;
  79         while (src < send) {
  80                 /* read uncompressed block size */
  81                 dlen = get_unaligned_be32(src);
  82                 src += 4;
  83
  84                 /* exit if last block */
  85                 if (dlen == 0) {
  86                         *dst_len = dst - start;
  87                         return LZO_E_OK;
  88                 }
  89
  90                 /* read compressed block size, and skip block checksum info */
  91                 slen = get_unaligned_be32(src);
  92                 src += 8;
  93
  94                 if (slen <= 0 || slen > dlen)
  95                         return LZO_E_ERROR;
  96
  97                 /* abort if buffer ran out of room */
  98                 if (dlen > remaining)
  99                         return LZO_E_OUTPUT_OVERRUN;
 100
 101                 /* decompress */
 102                 tmp = dlen;
 103                 r = lzo1x_decompress_safe((u8 *) src, slen, dst, &tmp);
 104
 105                 if (r != LZO_E_OK) {
 106                         *dst_len = dst - start;
 107                         return r;
 108                 }
 109
 110                 if (dlen != tmp)
 111                         return LZO_E_ERROR;
 112
 113                 src += slen;
 114                 dst += dlen;
 115                 remaining -= dlen;
 116         }
 117
 118         return LZO_E_INPUT_OVERRUN;
 119 }
 120
 121 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
 122                         unsigned char *out, size_t *out_len)
 123 {
 124         const unsigned char * const ip_end = in + in_len;
 125         unsigned char * const op_end = out + *out_len;
 126         const unsigned char *ip = in, *m_pos;
 127         unsigned char *op = out;
 128         size_t t;
 129
 130         *out_len = 0;
 131
 132         if (*ip > 17) {
 133                 t = *ip++ - 17;
 134                 if (t < 4)
 135                         goto match_next;
 136                 if (HAVE_OP(t, op_end, op))
 137                         goto output_overrun;
 138                 if (HAVE_IP(t + 1, ip_end, ip))
 139                         goto input_overrun;
 140                 do {
 141                         *op++ = *ip++;
 142                 } while (--t > 0);
 143                 goto first_literal_run;
 144         }
 145
 146         while ((ip < ip_end)) {
 147                 t = *ip++;
 148                 if (t >= 16)
 149                         goto match;
 150                 if (t == 0) {
 151                         if (HAVE_IP(1, ip_end, ip))
 152                                 goto input_overrun;
 153                         while (*ip == 0) {
 154                                 t += 255;
 155                                 ip++;
 156                                 if (HAVE_IP(1, ip_end, ip))
 157                                         goto input_overrun;
 158                         }
 159                         t += 15 + *ip++;
 160                 }
 161                 if (HAVE_OP(t + 3, op_end, op))
 162                         goto output_overrun;
 163                 if (HAVE_IP(t + 4, ip_end, ip))
 164                         goto input_overrun;
 165
 166                 COPY4(op, ip);
 167                 op += 4;
 168                 ip += 4;
 169                 if (--t > 0) {
 170                         if (t >= 4) {
 171                                 do {
 172                                         COPY4(op, ip);
 173                                         op += 4;
 174                                         ip += 4;
 175                                         t -= 4;
 176                                 } while (t >= 4);
 177                                 if (t > 0) {
 178                                         do {
 179                                                 *op++ = *ip++;
 180                                         } while (--t > 0);
 181                                 }
 182                         } else {
 183                                 do {
 184                                         *op++ = *ip++;
 185                                 } while (--t > 0);
 186                         }
 187                 }
 188
 189 first_literal_run:
 190                 t = *ip++;
 191                 if (t >= 16)
 192                         goto match;
 193                 m_pos = op - (1 + M2_MAX_OFFSET);
 194                 m_pos -= t >> 2;
 195                 m_pos -= *ip++ << 2;
 196
 197                 if (HAVE_LB(m_pos, out, op))
 198                         goto lookbehind_overrun;
 199
 200                 if (HAVE_OP(3, op_end, op))
 201                         goto output_overrun;
 202                 *op++ = *m_pos++;
 203                 *op++ = *m_pos++;
 204                 *op++ = *m_pos;
 205
 206                 goto match_done;
 207
 208                 do {
 209 match:
 210                         if (t >= 64) {
 211                                 m_pos = op - 1;
 212                                 m_pos -= (t >> 2) & 7;
 213                                 m_pos -= *ip++ << 3;
 214                                 t = (t >> 5) - 1;
 215                                 if (HAVE_LB(m_pos, out, op))
 216                                         goto lookbehind_overrun;
 217                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 218                                         goto output_overrun;
 219                                 goto copy_match;
 220                         } else if (t >= 32) {
 221                                 t &= 31;
 222                                 if (t == 0) {
 223                                         if (HAVE_IP(1, ip_end, ip))
 224                                                 goto input_overrun;
 225                                         while (*ip == 0) {
 226                                                 t += 255;
 227                                                 ip++;
 228                                                 if (HAVE_IP(1, ip_end, ip))
 229                                                         goto input_overrun;
 230                                         }
 231                                         t += 31 + *ip++;
 232                                 }
 233                                 m_pos = op - 1;
 234                                 m_pos -= get_unaligned_le16(ip) >> 2;
 235                                 ip += 2;
 236                         } else if (t >= 16) {
 237                                 m_pos = op;
 238                                 m_pos -= (t & 8) << 11;
 239
 240                                 t &= 7;
 241                                 if (t == 0) {
 242                                         if (HAVE_IP(1, ip_end, ip))
 243                                                 goto input_overrun;
 244                                         while (*ip == 0) {
 245                                                 t += 255;
 246                                                 ip++;
 247                                                 if (HAVE_IP(1, ip_end, ip))
 248                                                         goto input_overrun;
 249                                         }
 250                                         t += 7 + *ip++;
 251                                 }
 252                                 m_pos -= get_unaligned_le16(ip) >> 2;
 253                                 ip += 2;
 254                                 if (m_pos == op)
 255                                         goto eof_found;
 256                                 m_pos -= 0x4000;
 257                         } else {
 258                                 m_pos = op - 1;
 259                                 m_pos -= t >> 2;
 260                                 m_pos -= *ip++ << 2;
 261
 262                                 if (HAVE_LB(m_pos, out, op))
 263                                         goto lookbehind_overrun;
 264                                 if (HAVE_OP(2, op_end, op))
 265                                         goto output_overrun;
 266
 267                                 *op++ = *m_pos++;
 268                                 *op++ = *m_pos;
 269                                 goto match_done;
 270                         }
 271
 272                         if (HAVE_LB(m_pos, out, op))
 273                                 goto lookbehind_overrun;
 274                         if (HAVE_OP(t + 3 - 1, op_end, op))
 275                                 goto output_overrun;
 276
 277                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 278                                 COPY4(op, m_pos);
 279                                 op += 4;
 280                                 m_pos += 4;
 281                                 t -= 4 - (3 - 1);
 282                                 do {
 283                                         COPY4(op, m_pos);
 284                                         op += 4;
 285                                         m_pos += 4;
 286                                         t -= 4;
 287                                 } while (t >= 4);
 288                                 if (t > 0)
 289                                         do {
 290                                                 *op++ = *m_pos++;
 291                                         } while (--t > 0);
 292                         } else {
 293 copy_match:
 294                                 *op++ = *m_pos++;
 295                                 *op++ = *m_pos++;
 296                                 do {
 297                                         *op++ = *m_pos++;
 298                                 } while (--t > 0);
 299                         }
 300 match_done:
 301                         t = ip[-2] & 3;
 302                         if (t == 0)
 303                                 break;
 304 match_next:
 305                         if (HAVE_OP(t, op_end, op))
 306                                 goto output_overrun;
 307                         if (HAVE_IP(t + 1, ip_end, ip))
 308                                 goto input_overrun;
 309
 310                         *op++ = *ip++;
 311                         if (t > 1) {
 312                                 *op++ = *ip++;
 313                                 if (t > 2)
 314                                         *op++ = *ip++;
 315                         }
 316
 317                         t = *ip++;
 318                 } while (ip < ip_end);
 319         }
 320
 321         *out_len = op - out;
 322         return LZO_E_EOF_NOT_FOUND;
 323
 324 eof_found:
 325         *out_len = op - out;
 326         return (ip == ip_end ? LZO_E_OK :
 327                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 328 input_overrun:
 329         *out_len = op - out;
 330         return LZO_E_INPUT_OVERRUN;
 331
 332 output_overrun:
 333         *out_len = op - out;
 334         return LZO_E_OUTPUT_OVERRUN;
 335
 336 lookbehind_overrun:
 337         *out_len = op - out;
 338         return LZO_E_LOOKBEHIND_OVERRUN;
 339 }