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 <linux/kernel.h> 15#include <linux/lzo.h> 16#include <linux/string.h> 17#include <asm/byteorder.h> 18#include <asm/unaligned.h> 19#include "lzodefs.h" 20 21#define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x)) 22#define HAVE_OP(x, op_end, op) ((size_t)(op_end - op) < (x)) 23#define HAVE_LB(m_pos, out, op) (m_pos < out || m_pos >= op) 24 25#define COPY4(dst, src) \ 26 put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst)) 27 28static const unsigned char lzop_magic[] = { 29 0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a 30}; 31 32#define HEADER_HAS_FILTER 0x00000800L 33 34 35bool lzop_is_valid_header(const unsigned char *src) 36{ 37 int i; 38 /* read magic: 9 first bytes */ 39 for (i = 0; i < ARRAY_SIZE(lzop_magic); i++) { 40 if (*src++ != lzop_magic[i]) 41 return false; 42 } 43 return true; 44} 45 46static inline const unsigned char *parse_header(const unsigned char *src) 47{ 48 u16 version; 49 int i; 50 51 if (!lzop_is_valid_header(src)) 52 return NULL; 53 54 /* skip header */ 55 src += 9; 56 57 /* get version (2bytes), skip library version (2), 58 * 'need to be extracted' version (2) and 59 * method (1) */ 60 version = get_unaligned_be16(src); 61 src += 7; 62 if (version >= 0x0940) 63 src++; 64 if (get_unaligned_be32(src) & HEADER_HAS_FILTER) 65 src += 4; /* filter info */ 66 67 /* skip flags, mode and mtime_low */ 68 src += 12; 69 if (version >= 0x0940) 70 src += 4; /* skip mtime_high */ 71 72 i = *src++; 73 /* don't care about the file name, and skip checksum */ 74 src += i + 4; 75 76 return src; 77} 78 79int lzop_decompress(const unsigned char *src, size_t src_len, 80 unsigned char *dst, size_t *dst_len) 81{ 82 unsigned char *start = dst; 83 const unsigned char *send = src + src_len; 84 u32 slen, dlen; 85 size_t tmp, remaining; 86 int r; 87 88 src = parse_header(src); 89 if (!src) 90 return LZO_E_ERROR; 91 92 remaining = *dst_len; 93 while (src < send) { 94 /* read uncompressed block size */ 95 dlen = get_unaligned_be32(src); 96 src += 4; 97 98 /* exit if last block */ 99 if (dlen == 0) { 100 *dst_len = dst - start; 101 return LZO_E_OK; 102 } 103 104 /* read compressed block size, and skip block checksum info */ 105 slen = get_unaligned_be32(src); 106 src += 8; 107 108 if (slen <= 0 || slen > dlen) 109 return LZO_E_ERROR; 110 111 /* abort if buffer ran out of room */ 112 if (dlen > remaining) 113 return LZO_E_OUTPUT_OVERRUN; 114 115 /* When the input data is not compressed at all, 116 * lzo1x_decompress_safe will fail, so call memcpy() 117 * instead */ 118 if (dlen == slen) { 119 memcpy(dst, src, slen); 120 } else { 121 /* decompress */ 122 tmp = dlen; 123 r = lzo1x_decompress_safe((u8 *)src, slen, dst, &tmp); 124 125 if (r != LZO_E_OK) { 126 *dst_len = dst - start; 127 return r; 128 } 129 130 if (dlen != tmp) 131 return LZO_E_ERROR; 132 } 133 134 src += slen; 135 dst += dlen; 136 remaining -= dlen; 137 } 138 139 return LZO_E_INPUT_OVERRUN; 140} 141 142int lzo1x_decompress_safe(const unsigned char *in, size_t in_len, 143 unsigned char *out, size_t *out_len) 144{ 145 const unsigned char * const ip_end = in + in_len; 146 unsigned char * const op_end = out + *out_len; 147 const unsigned char *ip = in, *m_pos; 148 unsigned char *op = out; 149 size_t t; 150 151 *out_len = 0; 152 153 if (*ip > 17) { 154 t = *ip++ - 17; 155 if (t < 4) 156 goto match_next; 157 if (HAVE_OP(t, op_end, op)) 158 goto output_overrun; 159 if (HAVE_IP(t + 1, ip_end, ip)) 160 goto input_overrun; 161 do { 162 *op++ = *ip++; 163 } while (--t > 0); 164 goto first_literal_run; 165 } 166 167 while ((ip < ip_end)) { 168 t = *ip++; 169 if (t >= 16) 170 goto match; 171 if (t == 0) { 172 if (HAVE_IP(1, ip_end, ip)) 173 goto input_overrun; 174 while (*ip == 0) { 175 t += 255; 176 ip++; 177 if (HAVE_IP(1, ip_end, ip)) 178 goto input_overrun; 179 } 180 t += 15 + *ip++; 181 } 182 if (HAVE_OP(t + 3, op_end, op)) 183 goto output_overrun; 184 if (HAVE_IP(t + 4, ip_end, ip)) 185 goto input_overrun; 186 187 COPY4(op, ip); 188 op += 4; 189 ip += 4; 190 if (--t > 0) { 191 if (t >= 4) { 192 do { 193 COPY4(op, ip); 194 op += 4; 195 ip += 4; 196 t -= 4; 197 } while (t >= 4); 198 if (t > 0) { 199 do { 200 *op++ = *ip++; 201 } while (--t > 0); 202 } 203 } else { 204 do { 205 *op++ = *ip++; 206 } while (--t > 0); 207 } 208 } 209 210first_literal_run: 211 t = *ip++; 212 if (t >= 16) 213 goto match; 214 m_pos = op - (1 + M2_MAX_OFFSET); 215 m_pos -= t >> 2; 216 m_pos -= *ip++ << 2; 217 218 if (HAVE_LB(m_pos, out, op)) 219 goto lookbehind_overrun; 220 221 if (HAVE_OP(3, op_end, op)) 222 goto output_overrun; 223 *op++ = *m_pos++; 224 *op++ = *m_pos++; 225 *op++ = *m_pos; 226 227 goto match_done; 228 229 do { 230match: 231 if (t >= 64) { 232 m_pos = op - 1; 233 m_pos -= (t >> 2) & 7; 234 m_pos -= *ip++ << 3; 235 t = (t >> 5) - 1; 236 if (HAVE_LB(m_pos, out, op)) 237 goto lookbehind_overrun; 238 if (HAVE_OP(t + 3 - 1, op_end, op)) 239 goto output_overrun; 240 goto copy_match; 241 } else if (t >= 32) { 242 t &= 31; 243 if (t == 0) { 244 if (HAVE_IP(1, ip_end, ip)) 245 goto input_overrun; 246 while (*ip == 0) { 247 t += 255; 248 ip++; 249 if (HAVE_IP(1, ip_end, ip)) 250 goto input_overrun; 251 } 252 t += 31 + *ip++; 253 } 254 m_pos = op - 1; 255 m_pos -= get_unaligned_le16(ip) >> 2; 256 ip += 2; 257 } else if (t >= 16) { 258 m_pos = op; 259 m_pos -= (t & 8) << 11; 260 261 t &= 7; 262 if (t == 0) { 263 if (HAVE_IP(1, ip_end, ip)) 264 goto input_overrun; 265 while (*ip == 0) { 266 t += 255; 267 ip++; 268 if (HAVE_IP(1, ip_end, ip)) 269 goto input_overrun; 270 } 271 t += 7 + *ip++; 272 } 273 m_pos -= get_unaligned_le16(ip) >> 2; 274 ip += 2; 275 if (m_pos == op) 276 goto eof_found; 277 m_pos -= 0x4000; 278 } else { 279 m_pos = op - 1; 280 m_pos -= t >> 2; 281 m_pos -= *ip++ << 2; 282 283 if (HAVE_LB(m_pos, out, op)) 284 goto lookbehind_overrun; 285 if (HAVE_OP(2, op_end, op)) 286 goto output_overrun; 287 288 *op++ = *m_pos++; 289 *op++ = *m_pos; 290 goto match_done; 291 } 292 293 if (HAVE_LB(m_pos, out, op)) 294 goto lookbehind_overrun; 295 if (HAVE_OP(t + 3 - 1, op_end, op)) 296 goto output_overrun; 297 298 if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) { 299 COPY4(op, m_pos); 300 op += 4; 301 m_pos += 4; 302 t -= 4 - (3 - 1); 303 do { 304 COPY4(op, m_pos); 305 op += 4; 306 m_pos += 4; 307 t -= 4; 308 } while (t >= 4); 309 if (t > 0) 310 do { 311 *op++ = *m_pos++; 312 } while (--t > 0); 313 } else { 314copy_match: 315 *op++ = *m_pos++; 316 *op++ = *m_pos++; 317 do { 318 *op++ = *m_pos++; 319 } while (--t > 0); 320 } 321match_done: 322 t = ip[-2] & 3; 323 if (t == 0) 324 break; 325match_next: 326 if (HAVE_OP(t, op_end, op)) 327 goto output_overrun; 328 if (HAVE_IP(t + 1, ip_end, ip)) 329 goto input_overrun; 330 331 *op++ = *ip++; 332 if (t > 1) { 333 *op++ = *ip++; 334 if (t > 2) 335 *op++ = *ip++; 336 } 337 338 t = *ip++; 339 } while (ip < ip_end); 340 } 341 342 *out_len = op - out; 343 return LZO_E_EOF_NOT_FOUND; 344 345eof_found: 346 *out_len = op - out; 347 return (ip == ip_end ? LZO_E_OK : 348 (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN)); 349input_overrun: 350 *out_len = op - out; 351 return LZO_E_INPUT_OVERRUN; 352 353output_overrun: 354 *out_len = op - out; 355 return LZO_E_OUTPUT_OVERRUN; 356 357lookbehind_overrun: 358 *out_len = op - out; 359 return LZO_E_LOOKBEHIND_OVERRUN; 360} 361