linux/lib/lzo/lzo1x_decompress.c
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   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#ifndef STATIC
  15#include <linux/module.h>
  16#include <linux/kernel.h>
  17#endif
  18
  19#include <asm/unaligned.h>
  20#include <linux/lzo.h>
  21#include "lzodefs.h"
  22
  23#define HAVE_IP(x, ip_end, ip) ((size_t)(ip_end - ip) < (x))
  24#define HAVE_OP(x, op_end, op) ((size_t)(op_end - op) < (x))
  25#define HAVE_LB(m_pos, out, op) (m_pos < out || m_pos >= op)
  26
  27#define COPY4(dst, src) \
  28                put_unaligned(get_unaligned((const u32 *)(src)), (u32 *)(dst))
  29
  30int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
  31                        unsigned char *out, size_t *out_len)
  32{
  33        const unsigned char * const ip_end = in + in_len;
  34        unsigned char * const op_end = out + *out_len;
  35        const unsigned char *ip = in, *m_pos;
  36        unsigned char *op = out;
  37        size_t t;
  38
  39        *out_len = 0;
  40
  41        if (*ip > 17) {
  42                t = *ip++ - 17;
  43                if (t < 4)
  44                        goto match_next;
  45                if (HAVE_OP(t, op_end, op))
  46                        goto output_overrun;
  47                if (HAVE_IP(t + 1, ip_end, ip))
  48                        goto input_overrun;
  49                do {
  50                        *op++ = *ip++;
  51                } while (--t > 0);
  52                goto first_literal_run;
  53        }
  54
  55        while ((ip < ip_end)) {
  56                t = *ip++;
  57                if (t >= 16)
  58                        goto match;
  59                if (t == 0) {
  60                        if (HAVE_IP(1, ip_end, ip))
  61                                goto input_overrun;
  62                        while (*ip == 0) {
  63                                t += 255;
  64                                ip++;
  65                                if (HAVE_IP(1, ip_end, ip))
  66                                        goto input_overrun;
  67                        }
  68                        t += 15 + *ip++;
  69                }
  70                if (HAVE_OP(t + 3, op_end, op))
  71                        goto output_overrun;
  72                if (HAVE_IP(t + 4, ip_end, ip))
  73                        goto input_overrun;
  74
  75                COPY4(op, ip);
  76                op += 4;
  77                ip += 4;
  78                if (--t > 0) {
  79                        if (t >= 4) {
  80                                do {
  81                                        COPY4(op, ip);
  82                                        op += 4;
  83                                        ip += 4;
  84                                        t -= 4;
  85                                } while (t >= 4);
  86                                if (t > 0) {
  87                                        do {
  88                                                *op++ = *ip++;
  89                                        } while (--t > 0);
  90                                }
  91                        } else {
  92                                do {
  93                                        *op++ = *ip++;
  94                                } while (--t > 0);
  95                        }
  96                }
  97
  98first_literal_run:
  99                t = *ip++;
 100                if (t >= 16)
 101                        goto match;
 102                m_pos = op - (1 + M2_MAX_OFFSET);
 103                m_pos -= t >> 2;
 104                m_pos -= *ip++ << 2;
 105
 106                if (HAVE_LB(m_pos, out, op))
 107                        goto lookbehind_overrun;
 108
 109                if (HAVE_OP(3, op_end, op))
 110                        goto output_overrun;
 111                *op++ = *m_pos++;
 112                *op++ = *m_pos++;
 113                *op++ = *m_pos;
 114
 115                goto match_done;
 116
 117                do {
 118match:
 119                        if (t >= 64) {
 120                                m_pos = op - 1;
 121                                m_pos -= (t >> 2) & 7;
 122                                m_pos -= *ip++ << 3;
 123                                t = (t >> 5) - 1;
 124                                if (HAVE_LB(m_pos, out, op))
 125                                        goto lookbehind_overrun;
 126                                if (HAVE_OP(t + 3 - 1, op_end, op))
 127                                        goto output_overrun;
 128                                goto copy_match;
 129                        } else if (t >= 32) {
 130                                t &= 31;
 131                                if (t == 0) {
 132                                        if (HAVE_IP(1, ip_end, ip))
 133                                                goto input_overrun;
 134                                        while (*ip == 0) {
 135                                                t += 255;
 136                                                ip++;
 137                                                if (HAVE_IP(1, ip_end, ip))
 138                                                        goto input_overrun;
 139                                        }
 140                                        t += 31 + *ip++;
 141                                }
 142                                m_pos = op - 1;
 143                                m_pos -= get_unaligned_le16(ip) >> 2;
 144                                ip += 2;
 145                        } else if (t >= 16) {
 146                                m_pos = op;
 147                                m_pos -= (t & 8) << 11;
 148
 149                                t &= 7;
 150                                if (t == 0) {
 151                                        if (HAVE_IP(1, ip_end, ip))
 152                                                goto input_overrun;
 153                                        while (*ip == 0) {
 154                                                t += 255;
 155                                                ip++;
 156                                                if (HAVE_IP(1, ip_end, ip))
 157                                                        goto input_overrun;
 158                                        }
 159                                        t += 7 + *ip++;
 160                                }
 161                                m_pos -= get_unaligned_le16(ip) >> 2;
 162                                ip += 2;
 163                                if (m_pos == op)
 164                                        goto eof_found;
 165                                m_pos -= 0x4000;
 166                        } else {
 167                                m_pos = op - 1;
 168                                m_pos -= t >> 2;
 169                                m_pos -= *ip++ << 2;
 170
 171                                if (HAVE_LB(m_pos, out, op))
 172                                        goto lookbehind_overrun;
 173                                if (HAVE_OP(2, op_end, op))
 174                                        goto output_overrun;
 175
 176                                *op++ = *m_pos++;
 177                                *op++ = *m_pos;
 178                                goto match_done;
 179                        }
 180
 181                        if (HAVE_LB(m_pos, out, op))
 182                                goto lookbehind_overrun;
 183                        if (HAVE_OP(t + 3 - 1, op_end, op))
 184                                goto output_overrun;
 185
 186                        if (t >= 2 * 4 - (3 - 1) && (op - m_pos) >= 4) {
 187                                COPY4(op, m_pos);
 188                                op += 4;
 189                                m_pos += 4;
 190                                t -= 4 - (3 - 1);
 191                                do {
 192                                        COPY4(op, m_pos);
 193                                        op += 4;
 194                                        m_pos += 4;
 195                                        t -= 4;
 196                                } while (t >= 4);
 197                                if (t > 0)
 198                                        do {
 199                                                *op++ = *m_pos++;
 200                                        } while (--t > 0);
 201                        } else {
 202copy_match:
 203                                *op++ = *m_pos++;
 204                                *op++ = *m_pos++;
 205                                do {
 206                                        *op++ = *m_pos++;
 207                                } while (--t > 0);
 208                        }
 209match_done:
 210                        t = ip[-2] & 3;
 211                        if (t == 0)
 212                                break;
 213match_next:
 214                        if (HAVE_OP(t, op_end, op))
 215                                goto output_overrun;
 216                        if (HAVE_IP(t + 1, ip_end, ip))
 217                                goto input_overrun;
 218
 219                        *op++ = *ip++;
 220                        if (t > 1) {
 221                                *op++ = *ip++;
 222                                if (t > 2)
 223                                        *op++ = *ip++;
 224                        }
 225
 226                        t = *ip++;
 227                } while (ip < ip_end);
 228        }
 229
 230        *out_len = op - out;
 231        return LZO_E_EOF_NOT_FOUND;
 232
 233eof_found:
 234        *out_len = op - out;
 235        return (ip == ip_end ? LZO_E_OK :
 236                (ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN));
 237input_overrun:
 238        *out_len = op - out;
 239        return LZO_E_INPUT_OVERRUN;
 240
 241output_overrun:
 242        *out_len = op - out;
 243        return LZO_E_OUTPUT_OVERRUN;
 244
 245lookbehind_overrun:
 246        *out_len = op - out;
 247        return LZO_E_LOOKBEHIND_OVERRUN;
 248}
 249#ifndef STATIC
 250EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
 251
 252MODULE_LICENSE("GPL");
 253MODULE_DESCRIPTION("LZO1X Decompressor");
 254
 255#endif
 256
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