Powershell v2 zip function isn't zipping everything

Question

I can't quite remember where I found the answer that led me to use this Powershell snippet, but I've been using this script to zip a folder and the files contained within it:

param (
[string]$ZipFrom,
[string]$ZipTo
)
function Add-Zip
{
    param([string]$zipfilename)

    if(-not (test-path($zipfilename)))
    {
        set-content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
    (dir $zipfilename).IsReadOnly = $false  
    }

    $shellApplication = new-object -com shell.application
    $zipPackage = $shellApplication.NameSpace($zipfilename)

    foreach($file in $input) 
    { 
        $zipPackage.CopyHere($file.FullName)
        Start-sleep -milliseconds 500
    }
}

If(Test-path $ZipTo) {Remove-item $ZipTo}

dir $ZipFrom -Recurse | Add-Zip $ZipTo

Not sure what I'm missing, but it seems like it's zipping HALF of the files within the folder. I just tried this on a folder with 62 files in it, and I ended up with a zip archive with 31 files in it.

Are the other files perhaps hidden? `dir $ZipFrom -Recurse -force | Add-Zip $ZipTo`. Does `dir $ZipFrom -Recurse` show _all the files_ that should be zipped? — Matt, Sep 26 '18 at 18:15
None of the missing files are marked as hidden, good thought though. — Jeffrey Van Laethem, Sep 26 '18 at 18:18
@Matt running just the `dir $ZipFrom -Recurse` does show all files. — Jeffrey Van Laethem, Sep 26 '18 at 18:23
Have you run this in interactive mode? I am guessing not because I think you are getting _File not found or no read permission_ errors. — Matt, Sep 26 '18 at 19:02
Is the number of files that successfully get zipped the same _every time_? Need to test more but I find it changes based on the sleep time I set. — Matt, Sep 26 '18 at 19:03
Do you get a tmp file with the same basename as the zip created as well? — Matt, Sep 26 '18 at 19:04
I am guessing that `CopyHere()` is not waiting for the file to finish being zipped and it is having issues doing multiple operations at once. perhaps a larger timeout, for testing purposes, would compensate for this Surely this is documented somewhere. — Matt, Sep 26 '18 at 19:06
Not useful but https://www.petenetlive.com/KB/Article/0000774 suggests that size is an issue. — Matt, Sep 26 '18 at 19:08
This also might be related: https://stackoverflow.com/questions/14699767/copy-folder-contents-to-a-created-zip-file-file-not-found-or-no-read-permissi — Matt, Sep 26 '18 at 19:09
Looks like several of the largest files to be zipped ARE making it through the process, so while the KB article above is worth noting, I don't think it's the issue here. — Jeffrey Van Laethem, Sep 26 '18 at 20:12
@ArcSet access to 7Zip was removed in the environment I'm working in. — Jeffrey Van Laethem, Sep 26 '18 at 20:46
Looks like expanding the sleep time to 2000 ms is getting things done. I really wish I could just use 7Zip. — Jeffrey Van Laethem, Sep 27 '18 at 14:38
So you are restricted to using PSv2? 7Zip is portable... can you not bundle that with your script then? — Matt, Sep 27 '18 at 16:25
Yeah, PSv2, and 7Zip is to be nowhere in our environment. :( — Jeffrey Van Laethem, Sep 27 '18 at 17:02

Rich Moss · Answer 1 · 2019-04-23T18:28:15.107

You're experiencing the same issue that others have noticed when using the Shell.Application's CopyHere() command. It's asynchronous (non-blocking) and doesn't report completed events.

Adding a Sleep() won't work reliably for large files because the Shell.Application object will be disposed and disconnect from its child threads before they've completed.

Try repeatedly checking for the existence of the destination file like in the linked answer. Hope this helps!

Powershell v2 zip function isn't zipping everything

1 Answers1