Databases
StackOverflow2013
Postsdbo
POUnclarity about usage of LZ functions
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POUnclarity about usage of LZ functions
    primarykey
    data
    text
    <p><strong>Note:</strong> this question is about the Windows LZ functions, which are <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/aa364232%28v=vs.85%29.aspx" rel="nofollow">File Management Functions</a> beginning with the prefix LZ: LZOpenFile, LZCopy, LZClose, etc. If Google isn't wrong, these are probably among the most poorly documented functions of the Windows API.</p> <p>I'm trying to figure out what kind of files are actually suited for usage with the Windows LZ functions. The official documentation mentions "data that was compressed using Compress.exe", but the functions are also able to handle uncompressed files, in which case no decompression is applied.</p> <p>Now, when I compress a file with the compress.exe utility from the resource kit (using either the -Z or -ZX switches), and then decompress it using the procedure <a href="http://msdn.microsoft.com/en-us/library/windows/desktop/aa363901%28v=vs.85%29.aspx" rel="nofollow">described here</a>, all I get is the source file unchanged, as if it were not compressed as expected. Even with a compressed file from the original Windows XP setup CD (those named with an underscore at the end in the i386 folder), I get the same result. Conclusion: no matter what file I try to decompress, I get it back unchanged.</p> <p>The code I'm using is pretty straightforward, it basically reproduces the steps described in the MSDN article, so if I have a bug, I guess it must be somewhere else. But I'm still prone to thinking I'm just using the wrong input files. Does anyone have any experience with those LZ functions already? Here's my code in C++.</p> <pre><code>#include &lt;iostream&gt; #include &lt;Windows.h&gt; using namespace std; int main(int argc, char ** argv) { OFSTRUCT ofs1, ofs2; INT hfSrc = -1, hfDest = -1; if (argc &lt;= 2) { cerr &lt;&lt; "Usage: LZTEST Source Destination"; return 1; } __try { hfSrc = LZOpenFile(argv[1], &amp;ofs1, OF_READ); if (hfSrc &lt; 0) { cerr &lt;&lt; "Error invoking LZOpenFile on source file: " &lt;&lt; hfSrc; return 1; } hfDest = LZOpenFile(argv[2], &amp;ofs2, OF_CREATE); if (hfDest &lt; 0) { cerr &lt;&lt; "Error invoking LZOpenFile on destination file: " &lt;&lt; hfDest; return 1; } INT result = LZCopy(hfSrc, hfDest); if (result &lt; 0) { cerr &lt;&lt; "Error invoking LZCopy: " &lt;&lt; result; return 1; } } __finally { if (hfSrc &gt;= 0) LZClose(hfSrc); if (hfDest &gt;= 0) LZClose(hfDest); } cout &lt;&lt; "Success"; return 0; } </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USBenjamin
    1. USGOTO 0
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POUnclarity about usage of LZ functions
      1. USGOTO 0
      1. VTBountyStart
    2. VO
      singulars
      1. POUnclarity about usage of LZ functions
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POUnclarity about usage of LZ functions
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI tried your sample code verbatim and it works fine for me. Make sure you're actually using it on a file compressed with `compress.exe`. The `LZCopy` function looks for a header (`SZDD\x88\xf0\x27\x33`) and will only uncompress if the input file begins with those 8 bytes.
      singulars
      1. POUnclarity about usage of LZ functions
      1. USJonathan Potter
    2. CO@JonathanPotter where did you find `compress.exe`? I was using the one from the Windows Server 2003 Resource Kit Tools, and that was the problem.
      singulars
      1. POUnclarity about usage of LZ functions
      1. USGOTO 0
    3. COOne option might be to grab a copy of VS6 and the accompanying MSDN docs and check there. Since they're significantly older (10+ years) there may be some information in there that will help you.
      singulars
      1. POUnclarity about usage of LZ functions
      1. USCaptain Obvlious
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload