lib/lzo/lzo1x_decompress.c

   1 /*
   2  *  LZO1X Decompressor from MiniLZO
   3  *
   4  *  Copyright (C) 1996-2005 Markus F.X.J. Oberhumer <[email protected]>
   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 <[email protected]>
  11  *  Richard Purdie <[email protected]>
  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
  34 bool lzop_is_valid_header(const unsigned char *src)
  35 {
  36         int i;
  37         /* read magic: 9 first bytes */
  38         for (i = 0; i < ARRAY_SIZE(lzop_magic); i++) {
  39                 if (*src++ != lzop_magic[i])
  40                         return false;
  41         }
  42         return true;
  43 }
  44
  45 static inline const unsigned char *parse_header(const unsigned char *src)
  46 {
  47         u16 version;
  48         int i;
  49
  50         if (!lzop_is_valid_header(src))
  51                 return NULL;
  52
  53         /* skip header */
  54         src += 9;
  55
  56         /* get version (2bytes), skip library version (2),
  57          * 'need to be extracted' version (2) and
  58          * method (1) */
  59         version = get_unaligned_be16(src);
  60         src += 7;
  61         if (version >= 0x0940)
  62                 src++;
  63         if (get_unaligned_be32(src) & HEADER_HAS_FILTER)
  64                 src += 4; /* filter info */
  65
  66         /* skip flags, mode and mtime_low */
  67         src += 12;
  68         if (version >= 0x0940)
  69                 src += 4;       /* skip mtime_high */
  70
  71         i = *src++;
  72         /* don't care about the file name, and skip checksum */
  73         src += i + 4;
  74
  75         return src;
  76 }
  77
  78 int lzop_decompress(const unsigned char *src, size_t src_len,
  79                     unsigned char *dst, size_t *dst_len)
  80 {
  81         unsigned char *start = dst;
  82         const unsigned char *send = src + src_len;
  83         u32 slen, dlen;
  84         size_t tmp, remaining;
  85         int r;
  86
  87         src = parse_header(src);
  88         if (!src)
  89                 return LZO_E_ERROR;
  90
  91         remaining = *dst_len;
  92         while (src < send) {
  93                 /* read uncompressed block size */
  94                 dlen = get_unaligned_be32(src);
  95                 src += 4;
  96
  97                 /* exit if last block */
  98                 if (dlen == 0) {
  99                         *dst_len = dst - start;
 100                         return LZO_E_OK;
 101                 }
 102
 103                 /* read compressed block size, and skip block checksum info */
 104                 slen = get_unaligned_be32(src);
 105                 src += 8;
 106
 107                 if (slen <= 0 || slen > dlen)
 108                         return LZO_E_ERROR;
 109
 110                 /* abort if buffer ran out of room */
 111                 if (dlen > remaining)
 112                         return LZO_E_OUTPUT_OVERRUN;
 113
 114                 /* When the input data is not compressed at all,
 115                  * lzo1x_decompress_safe will fail, so call memcpy()
 116                  * instead */
 117                 if (dlen == slen) {
 118                         memcpy(dst, src, slen);
 119                 } else {
 120                         /* decompress */
 121                         tmp = dlen;
 122                         r = lzo1x_decompress_safe((u8 *)src, slen, dst, &tmp);
 123
 124                         if (r != LZO_E_OK) {
 125                                 *dst_len = dst - start;
 126                                 return r;
 127                         }
 128
 129                         if (dlen != tmp)
 130                                 return LZO_E_ERROR;
 131                 }
 132
 133                 src += slen;
 134                 dst += dlen;
 135                 remaining -= dlen;
 136         }
 137
 138         return LZO_E_INPUT_OVERRUN;
 139 }
 140
 141 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
 142                         unsigned char *out, size_t *out_len)
 143 {
 144         const unsigned char * const ip_end = in + in_len;
 145         unsigned char * const op_end = out + *out_len;
 146         const unsigned char *ip = in, *m_pos;
 147         unsigned char *op = out;
 148         size_t t;
 149
 150         *out_len = 0;
 151
 152         if (*ip > 17) {
 153                 t = *ip++ - 17;
 154                 if (t < 4)
 155                         goto match_next;
 156                 if (HAVE_OP(t, op_end, op))
 157                         goto output_overrun;
 158                 if (HAVE_IP(t + 1, ip_end, ip))
 159                         goto input_overrun;
 160                 do {
 161                         *op++ = *ip++;
 162                 } while (--t > 0);
 163                 goto first_literal_run;
 164         }
 165
 166         while ((ip < ip_end)) {
 167                 t = *ip++;
 168                 if (t >= 16)
 169                         goto match;
 170                 if (t == 0) {
 171                         if (HAVE_IP(1, ip_end, ip))
 172                                 goto input_overrun;
 173                         while (*ip == 0) {
 174                                 t += 255;
 175                                 ip++;
 176                                 if (HAVE_IP(1, ip_end, ip))
 177                                         goto input_overrun;
 178                         }
 179                         t += 15 + *ip++;
 180                 }
 181                 if (HAVE_OP(t + 3, op_end, op))
 182                         goto output_overrun;
 183                 if (HAVE_IP(t + 4, ip_end, ip))
 184                         goto input_overrun;
 185
 186                 COPY4(op, ip);
 187                 op += 4;
 188                 ip += 4;
 189                 if (--t > 0) {
 190                         if (t >= 4) {
 191                                 do {
 192                                         COPY4(op, ip);
 193                                         op += 4;
 194                                         ip += 4;
 195                                         t -= 4;
 196                                 } while (t >= 4);
 197                                 if (t > 0) {
 198                                         do {
 199                                                 *op++ = *ip++;
 200                                         } while (--t > 0);
 201                                 }
 202                         } else {
 203                                 do {
 204                                         *op++ = *ip++;
 205                                 } while (--t > 0);
 206                         }
 207                 }
 208
 209 first_literal_run:
 210                 t = *ip++;
 211                 if (t >= 16)
 212                         goto match;
 213                 m_pos = op - (1 + M2_MAX_OFFSET);
 214                 m_pos -= t >> 2;
 215                 m_pos -= *ip++ << 2;
 216
 217                 if (HAVE_LB(m_pos, out, op))
 218                         goto lookbehind_overrun;
 219
 220                 if (HAVE_OP(3, op_end, op))
 221                         goto output_overrun;
 222                 *op++ = *m_pos++;
 223                 *op++ = *m_pos++;
 224                 *op++ = *m_pos;
 225
 226                 goto match_done;
 227
 228                 do {
 229 match:
 230                         if (t >= 64) {
 231                                 m_pos = op - 1;
 232                                 m_pos -= (t >> 2) & 7;
 233                                 m_pos -= *ip++ << 3;
 234                                 t = (t >> 5) - 1;
 235                                 if (HAVE_LB(m_pos, out, op))
 236                                         goto lookbehind_overrun;
 237                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 238                                         goto output_overrun;
 239                                 goto copy_match;
 240                         } else if (t >= 32) {
 241                                 t &= 31;
 242                                 if (t == 0) {
 243                                         if (HAVE_IP(1, ip_end, ip))
 244                                                 goto input_overrun;
 245                                         while (*ip == 0) {
 246                                                 t += 255;
 247                                                 ip++;
 248                                                 if (HAVE_IP(1, ip_end, ip))
 249                                                         goto input_overrun;
 250                                         }
 251                                         t += 31 + *ip++;
 252                                 }
 253                                 m_pos = op - 1;
 254                                 m_pos -= get_unaligned_le16(ip) >> 2;
 255                                 ip += 2;
 256                         } else if (t >= 16) {
 257                                 m_pos = op;
 258                                 m_pos -= (t & 8) << 11;
 259
 260                                 t &= 7;
 261                                 if (t == 0) {
 262                                         if (HAVE_IP(1, ip_end, ip))
 263                                                 goto input_overrun;
 264                                         while (*ip == 0) {
 265                                                 t += 255;
 266                                                 ip++;
 267                                                 if (HAVE_IP(1, ip_end, ip))
 268                                                         goto input_overrun;
 269                                         }
 270                                         t += 7 + *ip++;
 271                                 }
 272                                 m_pos -= get_unaligned_le16(ip) >> 2;
 273                                 ip += 2;
 274                                 if (m_pos == op)
 275                                         goto eof_found;
 276                                 m_pos -= 0x4000;
 277                         } else {
 278                                 m_pos = op - 1;
 279                                 m_pos -= t >> 2;
 280                                 m_pos -= *ip++ << 2;
 281
 282                                 if (HAVE_LB(m_pos, out, op))
 283                                         goto lookbehind_overrun;
 284                                 if (HAVE_OP(2, op_end, op))
 285                                         goto output_overrun;
 286
 287                                 *op++ = *m_pos++;
 288                                 *op++ = *m_pos;
 289                                 goto match_done;
 290                         }
 291
 292                         if (HAVE_LB(m_pos, out, op))
 293                                 goto lookbehind_overrun;
 294                         if (HAVE_OP(t + 3 - 1, op_end, op))
 295                                 goto output_overrun;
 296
 297                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 298                                 COPY4(op, m_pos);
 299                                 op += 4;
 300                                 m_pos += 4;
 301                                 t -= 4 - (3 - 1);
 302                                 do {
 303                                         COPY4(op, m_pos);
 304                                         op += 4;
 305                                         m_pos += 4;
 306                                         t -= 4;
 307                                 } while (t >= 4);
 308                                 if (t > 0)
 309                                         do {
 310                                                 *op++ = *m_pos++;
 311                                         } while (--t > 0);
 312                         } else {
 313 copy_match:
 314                                 *op++ = *m_pos++;
 315                                 *op++ = *m_pos++;
 316                                 do {
 317                                         *op++ = *m_pos++;
 318                                 } while (--t > 0);
 319                         }
 320 match_done:
 321                         t = ip[-2] & 3;
 322                         if (t == 0)
 323                                 break;
 324 match_next:
 325                         if (HAVE_OP(t, op_end, op))
 326                                 goto output_overrun;
 327                         if (HAVE_IP(t + 1, ip_end, ip))
 328                                 goto input_overrun;
 329
 330                         *op++ = *ip++;
 331                         if (t > 1) {
 332                                 *op++ = *ip++;
 333                                 if (t > 2)
 334                                         *op++ = *ip++;
 335                         }
 336
 337                         t = *ip++;
 338                 } while (ip < ip_end);
 339         }
 340
 341         *out_len = op - out;
 342         return LZO_E_EOF_NOT_FOUND;
 343
 344 eof_found:
 345         *out_len = op - out;
 346         return (ip == ip_end ? LZO_E_OK :
 347                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 348 input_overrun:
 349         *out_len = op - out;
 350         return LZO_E_INPUT_OVERRUN;
 351
 352 output_overrun:
 353         *out_len = op - out;
 354         return LZO_E_OUTPUT_OVERRUN;
 355
 356 lookbehind_overrun:
 357         *out_len = op - out;
 358         return LZO_E_LOOKBEHIND_OVERRUN;
 359 }