Is there a way of manipulating zip file contents in memory with Powershell?

Question

I\'m currently trying to write a powershell function which works with the output of the Lync powershell cmdlet \"Export-CsConfiguration -AsBytes\". When using implicit Power

Answer 1

Making the "Made up Powershell function" a reality:

#
#   .SYNOPSIS
#       Extract a file from a byte[] zip file
#   
#   .DESCRIPTION
#       Extracts a file from a byte[] zip file as byte[]
#   
#   .PARAMETER ByteArray
#       Byte array containing zip file
#   
#   .PARAMETER FileInsideZipIWant
#       The file inside zip I want
#   
#   .PARAMETER utf8
#       If the file is UTF-8 encoded, use this switch to get a string
#   
#   .EXAMPLE
#       PS C:\> $utf8str = Extract-FileFromInMemoryZip -ByteArray $ZipFileBytes -FileInsideZipIWant "DocItemSet.xml" -utf8
#       PS C:\> $utf8str = Extract-FileFromInMemoryZip $ZipFileBytes "DocItemSet.xml" -utf8
#       PS C:\> $bs = Extract-FileFromInMemoryZip $ZipFileBytes "DocItemSet.xml"        
#   
#   .OUTPUTS
#       string, byte[]
#   
#   .NOTES
#       Exactly as desired. You may want to change the name of the "FileInsideZipIWant" parameter.
#       Don't plan on extracting files larger than 2GB.
#
function Extract-FileFromInMemoryZip
{
    [CmdletBinding(DefaultParameterSetName = 'raw')]
    [OutputType([string], ParameterSetName = 'utf8')]
    [OutputType([byte[]], ParameterSetName = 'raw')]
    param
    (
        [Parameter(Mandatory, ValueFromPipelineByPropertyName, Position = 0,
                   HelpMessage = 'Byte array containing zip file')]
        [byte[]]$ByteArray,
        [Parameter(Mandatory, ValueFromPipelineByPropertyName, Position = 1,
                   HelpMessage = 'Single file to extract')]
        [string]$FileInsideZipIWant,
        [Parameter(ParameterSetName = 'utf8')]
        [switch]$utf8
    )

    BEGIN { Add-Type -AN System.IO.Compression -ea:Stop } # Stop on error

    PROCESS {
        $entry = (
            New-Object System.IO.Compression.ZipArchive(
                New-Object System.IO.MemoryStream ( ,$ByteArray)
            )
        ).GetEntry($FileInsideZipIWant)

        # Note ZipArchiveEntry.Length returns a long (rather than int),
        # but we can't conveniently construct arrays longer than System.Int32.MaxValue
        $b = [byte[]]::new($entry.Length)

        # Avoid StreamReader to (dramatically) improve performance
        # ...but it may be useful if the extracted file has a BOM header
        $entry.Open().Read($b, 0, $b.Length)

        write $(
            if ($utf8) { [System.Text.Encoding]::UTF8.GetString($b) }
            else { $b }
        )
    }
}