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