zip multiple directories in Powershell using .NET classes, instead of compress-archive

Question

I am trying to use .NET classes instead of native compress-archive to zip multiple directories (each containing sub-directories and files), as compress-archive is giving me occasional OutOfMemory Exception.

Some articles tell me .NET classes, makes for a more optimal approach.

My tools directory $toolsDir = 'C:\Users\Public\LocalTools' has more than one directory that need to be zipped (please note everything is a directory, not file) - whichever directory matches the regex pattern as in the code.

Below is my code:

$cmpname = $env:computername
$now = $(Get-Date -Format yyyyMMddmmhhss)
$pattern = '^(19|[2-9][0-9])\d{2}\-(0?[1-9]|1[012])\-(0[1-9]|[12]\d|3[01])T((?:[01]\d|2[0-3])\;[0-5]\d\;[0-5]\d)\.(\d{3}Z)\-' + [ regex ]::Escape($cmpname)
$toolsDir = 'C:\Users\Public\LocalTools'
$destPathZip = "C:\Users\Public\ToolsOutput.zip"

 
Add-Type -AssemblyName System.IO.Compression
Add-Type -AssemblyName System.IO.Compression.FileSystem
$CompressionLevel = [ System.IO.Compression.CompressionLevel ]::Optimal
$IncludeBaseDirectory = $false
$stream = New-Object System.IO.FileStream($destPathZip , [ System.IO.FileMode ]::OpenOrCreate)
$zip = New-Object System.IO.Compression.ZipArchive($stream , 'update')

 
$res = Get-ChildItem "${toolsDir}" | Where-Object {$_ .Name -match "${pattern}"}

if ($res -ne $null) {
    foreach ($dir in $res) {
       $source = "${toolsDir}\${dir}"
       [ System.IO.Compression.ZipFileExtensions ]::CreateEntryFromFile($destPathZip , $source , (Split-Path $source -Leaf), $CompressionLevel)

    }
}
else {
    Write-Host "Nothing to Archive!"

} 

Above code gives me this error:

When I researched about [ System.IO.Compression.ZipFileExtensions ]::CreateEntryFromFile , it is used to add files to a zip file already created. Is this the reason I am getting the error that I get ?

I also tried [ System.IO.Compression.ZipFile ]::CreateFromDirectory($source , $destPathZip , $CompressionLevel, $IncludeBaseDirectory) instead of [ System.IO.Compression.ZipFileExtensions ]::CreateEntryFromFile($destPathZip , $source , (Split-Path $source -Leaf), $CompressionLevel)

That gives me "The file 'C:\Users\Public\ToolsOutput.zip' already exists error.

How to change the code, in order to add multiple directories in the zip file.

Answer 1

There are 3 problems with your code currently:

1. First argument passed to CreateEntryFromFile() must be a ZipArchive object in which to add the new entry - in your case you'll want to pass the $zip which you've already created for this purpose.
2. CreateEntryFromFile only creates 1 entry for 1 file per call - to recreate a whole directory substructure you need to calculate the correct entry path for each file, eg. subdirectory/subsubdirectory/file.exe
3. You need to properly dispose of both the ZipArchive and the underlying file stream instances in order for the data to be persisted on disk. For this, you'll need a try/finally statement.

Additionally, there's no need to create the file if there are no files to archive :)

$cmpname = $env:computername
$pattern = '^(19|[2-9][0-9])\d{2}\-(0?[1-9]|1[012])\-(0[1-9]|[12]\d|3[01])T((?:[01]\d|2[0-3])\;[0-5]\d\;[0-5]\d)\.(\d{3}Z)\-' + [regex]::Escape($cmpname)
$toolsDir = 'C:\Users\Public\LocalTools'
$destPathZip = "C:\Users\Public\ToolsOutput.zip"

Add-Type -AssemblyName System.IO.Compression
Add-Type -AssemblyName System.IO.Compression.FileSystem

$CompressionLevel = [System.IO.Compression.CompressionLevel]::Optimal

$res = Get-ChildItem -LiteralPath $toolsDir | Where-Object { $_.Name -match $pattern }

if ($res) {
  try {
    # Create file + zip archive instances
    $stream = New-Object System.IO.FileStream($destPathZip, [System.IO.FileMode]::OpenOrCreate)
    $zip = New-Object System.IO.Compression.ZipArchive($stream, [System.IO.Compression.ZipArchiveMode]::Update)

    # Discover all files to archive
    foreach ($file in $res |Get-ChildItem -File -Recurse) {
      $source = $dir.FullName

      # calculate correct relative path to the archive entry
      $relativeFilePath = [System.IO.Path]::GetRelativePath($toolsDir, $source)
      $entryName = $relativeFilePath.Replace('\', '/')

      # Make sure the first argument to CreateEntryFromFile is the ZipArchive object
      [System.IO.Compression.ZipFileExtensions]::CreateEntryFromFile($zip, $source, $entryName, $CompressionLevel)
    }
  }
  finally {
    # Clean up in reverse order
    $zip, $stream | Where-Object { $_ -is [System.IDisposable] } | ForEach-Object Dispose
  }
}
else {
  Write-Host "Nothing to Archive!"
}

Calling Dispose() on $zip will cause it to flush any un-written modifications to the underlying file stream and free any additional file handles it might have acquired, whereas calling Dispose() on the underlying file stream flushes those changes to the disk and closes the file handle.