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;
  72         int r;
  73
  74         src = parse_header(src);
  75         if (!src)
  76                 return LZO_E_ERROR;
  77
  78         while (src < send) {
  79                 /* read uncompressed block size */
  80                 dlen = get_unaligned_be32(src);
  81                 src += 4;
  82
  83                 /* exit if last block */
  84                 if (dlen == 0) {
  85                         *dst_len = dst - start;
  86                         return LZO_E_OK;
  87                 }
  88
  89                 /* read compressed block size, and skip block checksum info */
  90                 slen = get_unaligned_be32(src);
  91                 src += 8;
  92
  93                 if (slen <= 0 || slen > dlen)
  94                         return LZO_E_ERROR;
  95
  96                 /* decompress */
  97                 tmp = dlen;
  98                 r = lzo1x_decompress_safe((u8 *) src, slen, dst, &tmp);
  99
 100                 if (r != LZO_E_OK)
 101                         return r;
 102
 103                 if (dlen != tmp)
 104                         return LZO_E_ERROR;
 105
 106                 src += slen;
 107                 dst += dlen;
 108         }
 109
 110         return LZO_E_INPUT_OVERRUN;
 111 }
 112
 113 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
 114                         unsigned char *out, size_t *out_len)
 115 {
 116         const unsigned char * const ip_end = in + in_len;
 117         unsigned char * const op_end = out + *out_len;
 118         const unsigned char *ip = in, *m_pos;
 119         unsigned char *op = out;
 120         size_t t;
 121
 122         *out_len = 0;
 123
 124         if (*ip > 17) {
 125                 t = *ip++ - 17;
 126                 if (t < 4)
 127                         goto match_next;
 128                 if (HAVE_OP(t, op_end, op))
 129                         goto output_overrun;
 130                 if (HAVE_IP(t + 1, ip_end, ip))
 131                         goto input_overrun;
 132                 do {
 133                         *op++ = *ip++;
 134                 } while (--t > 0);
 135                 goto first_literal_run;
 136         }
 137
 138         while ((ip < ip_end)) {
 139                 t = *ip++;
 140                 if (t >= 16)
 141                         goto match;
 142                 if (t == 0) {
 143                         if (HAVE_IP(1, ip_end, ip))
 144                                 goto input_overrun;
 145                         while (*ip == 0) {
 146                                 t += 255;
 147                                 ip++;
 148                                 if (HAVE_IP(1, ip_end, ip))
 149                                         goto input_overrun;
 150                         }
 151                         t += 15 + *ip++;
 152                 }
 153                 if (HAVE_OP(t + 3, op_end, op))
 154                         goto output_overrun;
 155                 if (HAVE_IP(t + 4, ip_end, ip))
 156                         goto input_overrun;
 157
 158                 COPY4(op, ip);
 159                 op += 4;
 160                 ip += 4;
 161                 if (--t > 0) {
 162                         if (t >= 4) {
 163                                 do {
 164                                         COPY4(op, ip);
 165                                         op += 4;
 166                                         ip += 4;
 167                                         t -= 4;
 168                                 } while (t >= 4);
 169                                 if (t > 0) {
 170                                         do {
 171                                                 *op++ = *ip++;
 172                                         } while (--t > 0);
 173                                 }
 174                         } else {
 175                                 do {
 176                                         *op++ = *ip++;
 177                                 } while (--t > 0);
 178                         }
 179                 }
 180
 181 first_literal_run:
 182                 t = *ip++;
 183                 if (t >= 16)
 184                         goto match;
 185                 m_pos = op - (1 + M2_MAX_OFFSET);
 186                 m_pos -= t >> 2;
 187                 m_pos -= *ip++ << 2;
 188
 189                 if (HAVE_LB(m_pos, out, op))
 190                         goto lookbehind_overrun;
 191
 192                 if (HAVE_OP(3, op_end, op))
 193                         goto output_overrun;
 194                 *op++ = *m_pos++;
 195                 *op++ = *m_pos++;
 196                 *op++ = *m_pos;
 197
 198                 goto match_done;
 199
 200                 do {
 201 match:
 202                         if (t >= 64) {
 203                                 m_pos = op - 1;
 204                                 m_pos -= (t >> 2) & 7;
 205                                 m_pos -= *ip++ << 3;
 206                                 t = (t >> 5) - 1;
 207                                 if (HAVE_LB(m_pos, out, op))
 208                                         goto lookbehind_overrun;
 209                                 if (HAVE_OP(t + 3 - 1, op_end, op))
 210                                         goto output_overrun;
 211                                 goto copy_match;
 212                         } else if (t >= 32) {
 213                                 t &= 31;
 214                                 if (t == 0) {
 215                                         if (HAVE_IP(1, ip_end, ip))
 216                                                 goto input_overrun;
 217                                         while (*ip == 0) {
 218                                                 t += 255;
 219                                                 ip++;
 220                                                 if (HAVE_IP(1, ip_end, ip))
 221                                                         goto input_overrun;
 222                                         }
 223                                         t += 31 + *ip++;
 224                                 }
 225                                 m_pos = op - 1;
 226                                 m_pos -= get_unaligned_le16(ip) >> 2;
 227                                 ip += 2;
 228                         } else if (t >= 16) {
 229                                 m_pos = op;
 230                                 m_pos -= (t & 8) << 11;
 231
 232                                 t &= 7;
 233                                 if (t == 0) {
 234                                         if (HAVE_IP(1, ip_end, ip))
 235                                                 goto input_overrun;
 236                                         while (*ip == 0) {
 237                                                 t += 255;
 238                                                 ip++;
 239                                                 if (HAVE_IP(1, ip_end, ip))
 240                                                         goto input_overrun;
 241                                         }
 242                                         t += 7 + *ip++;
 243                                 }
 244                                 m_pos -= get_unaligned_le16(ip) >> 2;
 245                                 ip += 2;
 246                                 if (m_pos == op)
 247                                         goto eof_found;
 248                                 m_pos -= 0x4000;
 249                         } else {
 250                                 m_pos = op - 1;
 251                                 m_pos -= t >> 2;
 252                                 m_pos -= *ip++ << 2;
 253
 254                                 if (HAVE_LB(m_pos, out, op))
 255                                         goto lookbehind_overrun;
 256                                 if (HAVE_OP(2, op_end, op))
 257                                         goto output_overrun;
 258
 259                                 *op++ = *m_pos++;
 260                                 *op++ = *m_pos;
 261                                 goto match_done;
 262                         }
 263
 264                         if (HAVE_LB(m_pos, out, op))
 265                                 goto lookbehind_overrun;
 266                         if (HAVE_OP(t + 3 - 1, op_end, op))
 267                                 goto output_overrun;
 268
 269                         if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 270                                 COPY4(op, m_pos);
 271                                 op += 4;
 272                                 m_pos += 4;
 273                                 t -= 4 - (3 - 1);
 274                                 do {
 275                                         COPY4(op, m_pos);
 276                                         op += 4;
 277                                         m_pos += 4;
 278                                         t -= 4;
 279                                 } while (t >= 4);
 280                                 if (t > 0)
 281                                         do {
 282                                                 *op++ = *m_pos++;
 283                                         } while (--t > 0);
 284                         } else {
 285 copy_match:
 286                                 *op++ = *m_pos++;
 287                                 *op++ = *m_pos++;
 288                                 do {
 289                                         *op++ = *m_pos++;
 290                                 } while (--t > 0);
 291                         }
 292 match_done:
 293                         t = ip[-2] & 3;
 294                         if (t == 0)
 295                                 break;
 296 match_next:
 297                         if (HAVE_OP(t, op_end, op))
 298                                 goto output_overrun;
 299                         if (HAVE_IP(t + 1, ip_end, ip))
 300                                 goto input_overrun;
 301
 302                         *op++ = *ip++;
 303                         if (t > 1) {
 304                                 *op++ = *ip++;
 305                                 if (t > 2)
 306                                         *op++ = *ip++;
 307                         }
 308
 309                         t = *ip++;
 310                 } while (ip < ip_end);
 311         }
 312
 313         *out_len = op - out;
 314         return LZO_E_EOF_NOT_FOUND;
 315
 316 eof_found:
 317         *out_len = op - out;
 318         return (ip == ip_end ? LZO_E_OK :
 319                 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 320 input_overrun:
 321         *out_len = op - out;
 322         return LZO_E_INPUT_OVERRUN;
 323
 324 output_overrun:
 325         *out_len = op - out;
 326         return LZO_E_OUTPUT_OVERRUN;
 327
 328 lookbehind_overrun:
 329         *out_len = op - out;
 330         return LZO_E_LOOKBEHIND_OVERRUN;
 331 }