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Older Zip File failing IsZipFile test.

Nov 5, 2009 at 10:41 PM

I have an older zip file from a CD I created. It reads no problem with WinZip. I get a false when I test with ZipFile.IsZipFile(filename,true). I also attempted to extract with the WinForms Zip Tool and I get the error: Faisled to extract entry ASCII.CB -- Entry ASCII.CB uses an unsupported compression method (0x06, Unknown (0x0006)).

The original file was probably created with PKZIP. I believe the compression method was called Implode. I can send you a copy of the file and PKZIP if required. Here is a link to the header information:

Nov 5, 2009 at 11:48 PM

Hey there -

I definitely do not want that zip file.  I think you are asking me to implement the Implode algorithm, which seems like it would not be a small amount of work.


Nov 6, 2009 at 2:23 AM

How about returning an error reason like, unsupported compression, instead of not a valid zip file?


Nov 6, 2009 at 5:52 AM
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Nov 12, 2009 at 1:00 PM

Hey jprumos,

I just looked a little more closely at this and found that IsZipFile(file) returns TRUE, in fact it is a zip file.

IsZipFile(string, boolean) returns false, when the boolean param is true, which makes sense because the library cannot extract the zip file. 

So I think this is correct behavior.  

I'm going to close this workitem.


Nov 13, 2009 at 3:18 PM

Thank You for your response. I will check without using the boolean if the test fails with it.