Kirill K. Smirnov : winhelp: Fix LZ77 decompressor.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 27681bdfaf6878dbbf4b25f3b468e682dd2c253a
URL:    http://source.winehq.org/git/?p=wine.git;a=commit;h=27681bdfaf6878dbbf4b25f3b468e682dd2c253a

Author: Kirill K. Smirnov <lich at math.spbu.ru>
Date:   Fri Aug 11 19:28:49 2006 +0400

winhelp: Fix LZ77 decompressor.

---

 programs/winhelp/hlpfile.c |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/programs/winhelp/hlpfile.c b/programs/winhelp/hlpfile.c
index 92cc565..53f1a10 100644
--- a/programs/winhelp/hlpfile.c
+++ b/programs/winhelp/hlpfile.c
@@ -1498,8 +1498,16 @@ static BYTE *HLPFILE_UncompressLZ77(BYTE
                 int code   = GET_USHORT(ptr, 0);
                 int len    = 3 + (code >> 12);
                 int offset = code & 0xfff;
-                memcpy(newptr, newptr - offset - 1, len);
-                newptr += len;
+                /*
+                 * We must copy byte-by-byte here. We cannot use memcpy nor
+                 * memmove here. Just example:
+                 * a[]={1,2,3,4,5,6,7,8,9,10}
+                 * newptr=a+2;
+                 * offset=1;
+                 * We expect:
+                 * {1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 11, 12}
+                 */
+                for (; len>0; len--, newptr++) *newptr = *(newptr-offset-1);
                 ptr    += 2;
 	    }
             else *newptr++ = *ptr++;