src/lzf_d.c

   1 /*
   2  * Copyright (c) 2000-2007 Marc Alexander Lehmann <schmorp@schmorp.de>
   3  *
   4  * Redistribution and use in source and binary forms, with or without modifica-
   5  * tion, are permitted provided that the following conditions are met:
   6  *
   7  *   1.  Redistributions of source code must retain the above copyright notice,
   8  *       this list of conditions and the following disclaimer.
   9  *
  10  *   2.  Redistributions in binary form must reproduce the above copyright
  11  *       notice, this list of conditions and the following disclaimer in the
  12  *       documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
  15  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
  16  * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
  17  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
  18  * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  20  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  21  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
  22  * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  23  * OF THE POSSIBILITY OF SUCH DAMAGE.
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * the GNU General Public License ("GPL") version 2 or any later version,
  27  * in which case the provisions of the GPL are applicable instead of
  28  * the above. If you wish to allow the use of your version of this file
  29  * only under the terms of the GPL and not to allow others to use your
  30  * version of this file under the BSD license, indicate your decision
  31  * by deleting the provisions above and replace them with the notice
  32  * and other provisions required by the GPL. If you do not delete the
  33  * provisions above, a recipient may use your version of this file under
  34  * either the BSD or the GPL.
  35  */
  36
  37 #include "lzfP.h"
  38
  39 #if AVOID_ERRNO
  40 # define SET_ERRNO(n)
  41 #else
  42 # include <errno.h>
  43 # define SET_ERRNO(n) errno = (n)
  44 #endif
  45
  46 /*
  47 #if (__i386 || __amd64) && __GNUC__ >= 3
  48 # define lzf_movsb(dst, src, len)                \
  49    asm ("rep movsb"                              \
  50         : "=D" (dst), "=S" (src), "=c" (len)     \
  51         :  "0" (dst),  "1" (src),  "2" (len));
  52 #endif
  53 */
  54
  55 unsigned int
  56 lzf_decompress (const void *const in_data,  unsigned int in_len,
  57                 void             *out_data, unsigned int out_len)
  58 {
  59   u8 const *ip = (const u8 *)in_data;
  60   u8       *op = (u8 *)out_data;
  61   u8 const *const in_end  = ip + in_len;
  62   u8       *const out_end = op + out_len;
  63
  64   do
  65     {
  66       unsigned int ctrl = *ip++;
  67
  68       if (ctrl < (1 << 5)) /* literal run */
  69         {
  70           ctrl++;
  71
  72           if (op + ctrl > out_end)
  73             {
  74               SET_ERRNO (E2BIG);
  75               return 0;
  76             }
  77
  78 #if CHECK_INPUT
  79           if (ip + ctrl > in_end)
  80             {
  81               SET_ERRNO (EINVAL);
  82               return 0;
  83             }
  84 #endif
  85
  86 #ifdef lzf_movsb
  87           lzf_movsb (op, ip, ctrl);
  88 #else
  89           do
  90             *op++ = *ip++;
  91           while (--ctrl);
  92 #endif
  93         }
  94       else /* back reference */
  95         {
  96           unsigned int len = ctrl >> 5;
  97
  98           u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;
  99
 100 #if CHECK_INPUT
 101           if (ip >= in_end)
 102             {
 103               SET_ERRNO (EINVAL);
 104               return 0;
 105             }
 106 #endif
 107           if (len == 7)
 108             {
 109               len += *ip++;
 110 #if CHECK_INPUT
 111               if (ip >= in_end)
 112                 {
 113                   SET_ERRNO (EINVAL);
 114                   return 0;
 115                 }
 116 #endif
 117             }
 118
 119           ref -= *ip++;
 120
 121           if (op + len + 2 > out_end)
 122             {
 123               SET_ERRNO (E2BIG);
 124               return 0;
 125             }
 126
 127           if (ref < (u8 *)out_data)
 128             {
 129               SET_ERRNO (EINVAL);
 130               return 0;
 131             }
 132
 133 #ifdef lzf_movsb
 134           len += 2;
 135           lzf_movsb (op, ref, len);
 136 #else
 137           *op++ = *ref++;
 138           *op++ = *ref++;
 139
 140           do
 141             *op++ = *ref++;
 142           while (--len);
 143 #endif
 144         }
 145     }
 146   while (ip < in_end);
 147
 148   return op - (u8 *)out_data;
 149 }
 150