Hi, i've compressed a file using Microsoft's Compress.exe utility, and i can't decompress it with lzexpand.dll :/

LZOpenFile returns a valid handle (value greater than 0)

LZSeek(myhandle, 0, 2) seeks to the end of the compressed file (in opposition to what is said in platform sdk; it should seek to the end of uncompressed file).

LZRead fails with -3 (LZERROR_READ ).

any ideas how to decompress a file with lzexpand.dll ?
Posted on 2005-02-04 22:10:16 by ti_mo_n
Here's the complete app demonstrating how to use lzexpand.dll to decompress lz-compressed files. decompressing into memory is not supported. You can only "copy" the contents of a compressed file to a decompressed one.

// attempts to decompress an LZ-compressed file

#define UNICODE
#include <windows.h>
#include <Lzexpand.h>
#include <stdio.h>

TCHAR inbuf[512], outbuf[512]; // Buffers for filenames.
OFSTRUCT ofs1, ofs2;  // OpenFile structures. Required by LZ- functions.

TCHAR iname[] = L"Input filename:  ",
      oname[] = L"Output filename: ",
      sfmt1[] = L"%s";

INT main (INT argc, BYTE *argv[]) {
    INT rtval, rtval2;

    // prepare to decompress
    wprintf(sfmt1, iname);
    wscanf(sfmt1, inbuf);
    wprintf(sfmt1, oname);
    wscanf(sfmt1, outbuf);
    outbuf[511] = inbuf[511] = 0;

    // do the decompression. Write decompressed input file to the beginning of the output file.
    // file to memory, or memory to memory decompression seems not to be supported.

    rtval = LZOpenFile(inbuf, &ofs1, OF_PROMPT | OF_READ | OF_SHARE_DENY_WRITE);

    if ((rtval > -1) || (rtval < -8)) { //  error check
        rtval2 = LZOpenFile(outbuf, &ofs2, OF_WRITE | OF_SHARE_EXCLUSIVE | OF_CREATE);
        if ((rtval2 > -1) || (rtval2 < -8)) { //  error check
            LZCopy(rtval, rtval2);
        rtval = ERROR_SUCCESS;
    else rtval = ERROR_FILE_NOT_FOUND;
    return rtval;

Note: While compressing with Microsoft's compress.exe, you have to use the default "lz" method (not the "ms" one).
Posted on 2005-11-26 08:06:53 by ti_mo_n