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                 /* When the input data is not compressed at all,
 102                  * lzo1x_decompress_safe will fail, so call memcpy()
 103                  * instead */
 104                 if (dlen == slen) {
 105                         memcpy(dst, src, slen);
 106                 } else {
 107                         /* decompress */
 108                         tmp = dlen;
 109                         r = lzo1x_decompress_safe((u8 *)src, slen, dst, &tmp);
 110
 111                         if (r != LZO_E_OK) {
 112                                 *dst_len = dst - start;
 113                                 return r;
 114                         }
 115
 116                         if (dlen != tmp)
 117                                 return LZO_E_ERROR;
 118                 }
 119
 120                 src += slen;
 121                 dst += dlen;
 122                 remaining -= dlen;
 123         }
 124
 125         return LZO_E_INPUT_OVERRUN;
 126 }
 127
 128 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
 129                         unsigned char *out, size_t *out_len)
 130 {
 131         const unsigned char * const ip_end = in + in_len;
 132         unsigned char * const op_end = out + *out_len;
 133         const unsigned char *ip = in, *m_pos;
 134         unsigned char *op = out;
 135         size_t t;
 136
 137         *out_len = 0;
 138
 139         if (*ip > 17) {
 140                 t = *ip++ - 17;
 141                 if (t < 4)
 142                         goto match_next;
 143                 if (HAVE_OP(t, op_end, op))
 144                         goto output_overrun;
 145                 if (HAVE_IP(t + 1, ip_end, ip))
 146                         goto input_overrun;
 147                 do {
 148                         *op++ = *ip++;
 149                 } while (--t > 0);
 150                 goto first_literal_run;
 151         }
 152
 153         while ((ip < ip_end)) {
 154                 t = *ip++;
 155                 if (t >= 16)
 156                         goto match;
 157                 if (t == 0) {
 158                         if (HAVE_IP(1, ip_end, ip))
 159                                 goto input_overrun;
 160                         while (*ip == 0) {
 161                                 t += 255;
 162                                 ip++;
 163                                 if (HAVE_IP(1, ip_end, ip))
 164                                         goto input_overrun;
 165                         }
 166                         t += 15 + *ip++;
 167                 }
 168                 if (HAVE_OP(t + 3, op_end, op))
 169                         goto output_overrun;
 170                 if (HAVE_IP(t + 4, ip_end, ip))
 171                         goto input_overrun;
 172
 173                 COPY4(op, ip);
 174                 op += 4;
 175                 ip += 4;
 176                 if (--t > 0) {
 177                         if (t >= 4) {
 178                                 do {
 179                                         COPY4(op, ip);
 180                                         op += 4;
 181                                         ip += 4;
 182                                         t -= 4;
 183                                 } while (t >= 4);
 184                                 if (t > 0) {
 185                                         do {
 186                                                 *op++ = *ip++;
 187                                         } while (--t > 0);
 188                                 }
 189                         } else {
 190                                 do {
 191                                         *op++ = *ip++;
 192                                 } while (--t > 0);
 193                         }
 194                 }
 195
 196 first_literal_run:
 197                 t = *ip++;
 198                 if (t >= 16)
 199                         goto match;
 200                 m_pos = op - (1 + M2_MAX_OFFSET);
 201                 m_pos -= t >> 2;
 202                 m_pos -= *ip++ << 2;
 203
 204                 if (HAVE_LB(m_pos, out, op))
 205                         goto lookbehind_overrun;
 206
 207                 if (HAVE_OP(3, op_end, op))
 208                         goto output_overrun;
 209                 *op++ = *m_pos++;
 210                 *op++ = *m_pos++;
 211                 *op++ = *m_pos;
 212
 213                 goto match_done;
 214
 215                 do {
 216 match:
 217                         if (t >= 64) {
 218                                 m_pos = op - 1;
 219                                 m_pos -= (t >> 2) & 7;
 220                                 m_pos -= *ip++ << 3;
 221                                 t = (t >> 5) - 1;
 222                                 if (HAVE_LB(m_pos, out, op))
 223                                         goto lookbehind_overrun;
 224                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 225                                         goto output_overrun;
 226                                 goto copy_match;
 227                         } else if (t >= 32) {
 228                                 t &= 31;
 229                                 if (t == 0) {
 230                                         if (HAVE_IP(1, ip_end, ip))
 231                                                 goto input_overrun;
 232                                         while (*ip == 0) {
 233                                                 t += 255;
 234                                                 ip++;
 235                                                 if (HAVE_IP(1, ip_end, ip))
 236                                                         goto input_overrun;
 237                                         }
 238                                         t += 31 + *ip++;
 239                                 }
 240                                 m_pos = op - 1;
 241                                 m_pos -= get_unaligned_le16(ip) >> 2;
 242                                 ip += 2;
 243                         } else if (t >= 16) {
 244                                 m_pos = op;
 245                                 m_pos -= (t & 8) << 11;
 246
 247                                 t &= 7;
 248                                 if (t == 0) {
 249                                         if (HAVE_IP(1, ip_end, ip))
 250                                                 goto input_overrun;
 251                                         while (*ip == 0) {
 252                                                 t += 255;
 253                                                 ip++;
 254                                                 if (HAVE_IP(1, ip_end, ip))
 255                                                         goto input_overrun;
 256                                         }
 257                                         t += 7 + *ip++;
 258                                 }
 259                                 m_pos -= get_unaligned_le16(ip) >> 2;
 260                                 ip += 2;
 261                                 if (m_pos == op)
 262                                         goto eof_found;
 263                                 m_pos -= 0x4000;
 264                         } else {
 265                                 m_pos = op - 1;
 266                                 m_pos -= t >> 2;
 267                                 m_pos -= *ip++ << 2;
 268
 269                                 if (HAVE_LB(m_pos, out, op))
 270                                         goto lookbehind_overrun;
 271                                 if (HAVE_OP(2, op_end, op))
 272                                         goto output_overrun;
 273
 274                                 *op++ = *m_pos++;
 275                                 *op++ = *m_pos;
 276                                 goto match_done;
 277                         }
 278
 279                         if (HAVE_LB(m_pos, out, op))
 280                                 goto lookbehind_overrun;
 281                         if (HAVE_OP(t + 3 - 1, op_end, op))
 282                                 goto output_overrun;
 283
 284                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 285                                 COPY4(op, m_pos);
 286                                 op += 4;
 287                                 m_pos += 4;
 288                                 t -= 4 - (3 - 1);
 289                                 do {
 290                                         COPY4(op, m_pos);
 291                                         op += 4;
 292                                         m_pos += 4;
 293                                         t -= 4;
 294                                 } while (t >= 4);
 295                                 if (t > 0)
 296                                         do {
 297                                                 *op++ = *m_pos++;
 298                                         } while (--t > 0);
 299                         } else {
 300 copy_match:
 301                                 *op++ = *m_pos++;
 302                                 *op++ = *m_pos++;
 303                                 do {
 304                                         *op++ = *m_pos++;
 305                                 } while (--t > 0);
 306                         }
 307 match_done:
 308                         t = ip[-2] & 3;
 309                         if (t == 0)
 310                                 break;
 311 match_next:
 312                         if (HAVE_OP(t, op_end, op))
 313                                 goto output_overrun;
 314                         if (HAVE_IP(t + 1, ip_end, ip))
 315                                 goto input_overrun;
 316
 317                         *op++ = *ip++;
 318                         if (t > 1) {
 319                                 *op++ = *ip++;
 320                                 if (t > 2)
 321                                         *op++ = *ip++;
 322                         }
 323
 324                         t = *ip++;
 325                 } while (ip < ip_end);
 326         }
 327
 328         *out_len = op - out;
 329         return LZO_E_EOF_NOT_FOUND;
 330
 331 eof_found:
 332         *out_len = op - out;
 333         return (ip == ip_end ? LZO_E_OK :
 334                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 335 input_overrun:
 336         *out_len = op - out;
 337         return LZO_E_INPUT_OVERRUN;
 338
 339 output_overrun:
 340         *out_len = op - out;
 341         return LZO_E_OUTPUT_OVERRUN;
 342
 343 lookbehind_overrun:
 344         *out_len = op - out;
 345         return LZO_E_LOOKBEHIND_OVERRUN;
 346 }