A Script to Extract WIM and PSF from MSU Windows Update Files

jen1 said:

I want to share a script I created to extract WIM and PSF files from MSU Windows Update files. You might find it useful, as there are no existing tools that can extract PSF files!

Click to expand...

garlin said:

UUP dump's scripts use PSFExtractor, and it's been used by other image updating scripts. Doesn't that count?

Click to expand...

Maxstar said:

Nice script, and for personal use, I 've made a few changes so it will run as admin by default, with the installation of the 7Zip4PowerShell module to unpack the MSUs into the $base folder automatically.

Powershell:

function RunAsAdmin {
    $currentUser = New-Object Security.Principal.WindowsPrincipal $([Security.Principal.WindowsIdentity]::GetCurrent())
    $currentUser.IsInRole([Security.Principal.WindowsBuiltinRole]::Administrator)
}
if ((RunAsAdmin) -eq $false)  {
    if ($elevated) {
    } else {
        Start-Process powershell.exe -Verb RunAs -ArgumentList ('-noprofile -noexit -file "{0}" -elevated' -f ($myinvocation.MyCommand.Definition))
    }
    exit
}

# Install PowerShell Module
Write-Host "Istall 7Zip4PowerShell module ..."
Install-Module -Name 7Zip4PowerShell -Force

# Extract MSU Package
Write-Host "Extracting MSU-Package ..."
$msus = Get-ChildItem -Path $Base -Recurse | Where-Object {$_.Extension -eq ".msu"}
foreach($msu in $msus){
    Expand-7Zip $msu.FullName "$Base"

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jen1 said:

I want to share a script I created to extract WIM and PSF files from MSU Windows Update files. You might find it useful, as there are no existing tools that can extract PSF files!

This script is designed for simplicity. To use it, you will need to have 7-Zip installed. The default installation path is C:\Program Files\7-Zip\7z.exe, but you can easily change this in the script if your 7-Zip is located elsewhere (line 24).

How to Use the Script

Extract the MSU file to any folder of your choice.
Place the script inside the same folder. (I will not explain how to run a script in detail here; please refer to my previous thread Reduce the size of the uupdump ISO by approximately 2GB)
Run the script. It will automatically extract the WIM and PSF files into the folder.
After extraction, the script will delete the original WIM and PSF files.
It will also automatically install the SSU and prompt you to install the new KB.

I created this script to extract update files once and then install them quickly and easily in my VMs. Others may find different uses for it.

I want to clarify that I take no credit for the PSF extraction method, as I adapted that part from a script by uupdump. My goal was to make it more user-friendly and accessible for everyone.

I hope this script helps you as much as it has helped me! Feel free to ask any questions or provide feedback.

Powershell:

# =========================
# PSFX Unified Extractor
# =========================

$Base = $PSScriptRoot
Write-Host "Base folder: $Base"

# Detect WIM + PSF
$WimFile = Get-ChildItem $Base -Filter *.wim | Select-Object -First 1
$PsfFile = Get-ChildItem $Base -Filter *.psf | Select-Object -First 1
if (-not $WimFile -or -not $PsfFile) {
    Write-Error "Could not find both .wim and .psf files in $Base"
    exit 1
}
Write-Host "Found WIM: $($WimFile.Name)"
Write-Host "Found PSF: $($PsfFile.Name)"

# Create subfolder for extracted update (same name as WIM without extension)
$SubFolder = Join-Path $Base ($WimFile.BaseName)
if (-not (Test-Path $SubFolder)) {
    New-Item -ItemType Directory -Path $SubFolder | Out-Null
}

# --- Extract WIM with 7-Zip ---
$SevenZip = "C:\Program Files\7-Zip\7z.exe"

Write-Host "Extracting WIM into $SubFolder ..."

Start-Process -FilePath $SevenZip -ArgumentList "x `"$($WimFile.FullName)`" -o`"$SubFolder`" -y" -Wait -NoNewWindow
Remove-Item $WimFile.FullName -Force

# =========================
# Inline PSFX functions (from psfx.txt)
# =========================

function Native($DllFile){
  $Lib = [IO.Path]::GetFileName($DllFile)
  $Marshal = [System.Runtime.InteropServices.Marshal]
  $Module = [AppDomain]::CurrentDomain.DefineDynamicAssembly((Get-Random), 'Run').DefineDynamicModule((Get-Random))
  $Struct = $Module.DefineType('DI', 1048841, [ValueType], 0)
  [void]$Struct.DefineField('lpStart', [IntPtr], 6)
  [void]$Struct.DefineField('uSize', [UIntPtr], 6)
  [void]$Struct.DefineField('Editable', [Boolean], 6)
  $GLOBAL:DELTA_INPUT = $Struct.CreateType()
  $Struct = $Module.DefineType('DO', 1048841, [ValueType], 0)
  [void]$Struct.DefineField('lpStart', [IntPtr], 6)
  [void]$Struct.DefineField('uSize', [UIntPtr], 6)
  $GLOBAL:DELTA_OUTPUT = $Struct.CreateType()
  $Class = $Module.DefineType('PSFE', 1048961, [Object], 0)
  [void]$Class.DefinePInvokeMethod('LoadLibraryW','kernel32.dll',22,1,[IntPtr],@([String]),1,3).SetImplementationFlags(128)
  [void]$Class.DefinePInvokeMethod('ApplyDeltaB',$Lib,22,1,[Int32],@([Int64],[Type]$DELTA_INPUT,[Type]$DELTA_INPUT,[Type]$DELTA_OUTPUT.MakeByRefType()),1,3)
  [void]$Class.DefinePInvokeMethod('DeltaFree',$Lib,22,1,[Int32],@([IntPtr]),1,3)
  $GLOBAL:Win32 = $Class.CreateType()
}

function ApplyDelta($dBuffer,$dFile){
  $trg = [Activator]::CreateInstance($DELTA_OUTPUT)
  $src = [Activator]::CreateInstance($DELTA_INPUT)
  $dlt = [Activator]::CreateInstance($DELTA_INPUT)
  $dlt.lpStart = [System.Runtime.InteropServices.Marshal]::AllocHGlobal($dBuffer.Length)
  $dlt.uSize = [Activator]::CreateInstance([UIntPtr], @([UInt32]$dBuffer.Length))
  $dlt.Editable = $true
  [System.Runtime.InteropServices.Marshal]::Copy($dBuffer,0,$dlt.lpStart,$dBuffer.Length)
  [void]$Win32::ApplyDeltaB(0,$src,$dlt,[ref]$trg)
  if ($trg.lpStart -eq [IntPtr]::Zero){ return }
  $out = New-Object byte[] $trg.uSize.ToUInt32()
  [System.Runtime.InteropServices.Marshal]::Copy($trg.lpStart,$out,0,$out.Length)
  [IO.File]::WriteAllBytes($dFile,$out)
  if ($dlt.lpStart -ne [IntPtr]::Zero){ [System.Runtime.InteropServices.Marshal]::FreeHGlobal($dlt.lpStart) }
  if ($trg.lpStart -ne [IntPtr]::Zero){ [void]$Win32::DeltaFree($trg.lpStart) }
}

function G($DirectoryName){
  $DeltaList = [ordered]@{}
  $doc = New-Object xml
  $doc.Load($DirectoryName + "\express.psf.cix.xml")
  $child = $doc.FirstChild.NextSibling.FirstChild
  while(!$child.LocalName.Equals("Files")){ $child = $child.NextSibling }
  $FileList = $child.ChildNodes
  foreach($file in $FileList){
    $fileChild = $file.FirstChild
    while(!$fileChild.LocalName.Equals("Delta")){ $fileChild = $fileChild.NextSibling }
    $deltaChild = $fileChild.FirstChild
    while(!$deltaChild.LocalName.Equals("Source")){ $deltaChild = $deltaChild.NextSibling }
    $DeltaList[$($file.id)] = @{
      name=$file.name;
      time=$file.time;
      stype=$deltaChild.type;
      offset=$deltaChild.offset;
      length=$deltaChild.length
    }
  }
  return $DeltaList
}

function P($CabFile,$DllFile='msdelta.dll'){
  if ($DllFile -eq 'msdelta.dll' -and (Test-Path "$env:SystemRoot\System32\UpdateCompression.dll")){
    $DllFile = "$env:SystemRoot\System32\UpdateCompression.dll"
  }
  Native $DllFile
  [void]$Win32::LoadLibraryW($DllFile)
  $DirectoryName = $CabFile.Substring(0,$CabFile.LastIndexOf('.'))
  $PSFFile = $DirectoryName + ".psf"
  $null = [IO.Directory]::CreateDirectory($DirectoryName)
  $DeltaList = G $DirectoryName
  $PSFFileStream = [IO.File]::OpenRead([IO.Path]::GetFullPath($PSFFile))
  $cwd = [IO.Path]::GetFullPath($DirectoryName)
  [Environment]::CurrentDirectory = $cwd
  $null = [IO.Directory]::CreateDirectory("000")
  foreach($DeltaFile in $DeltaList.Values){
    $FullFileName = $DeltaFile.name
    if (Test-Path $FullFileName){ continue }
    $ShortFold = [IO.Path]::GetDirectoryName($FullFileName)
    $ShortFile = [IO.Path]::GetFileName($FullFileName)
    $UseRobo = (($cwd + '\' + $FullFileName).Length -gt 255) -or (($cwd + '\' + $ShortFold).Length -gt 248)
    if ($UseRobo -eq 0 -and $ShortFold.IndexOf("_") -ne -1){ $null = [IO.Directory]::CreateDirectory($ShortFold) }
    if ($UseRobo -eq 0){ $WhereFile = $FullFileName } else { $WhereFile = "000\" + $ShortFile }
    try { [void]$PSFFileStream.Seek($DeltaFile.offset,0) } catch {}
    $Buffer = New-Object byte[] $DeltaFile.length
    try { [void]$PSFFileStream.Read($Buffer,0,$DeltaFile.length) } catch {}
    $OutputFileStream = [IO.File]::Create($WhereFile)
    try { [void]$OutputFileStream.Write($Buffer,0,$DeltaFile.length) } catch {}
    [void]$OutputFileStream.Close()
    if ($DeltaFile.stype -eq "PA30" -or $DeltaFile.stype -eq "PA31"){ ApplyDelta $Buffer $WhereFile }
    $null = [IO.File]::SetLastWriteTimeUtc($WhereFile,[DateTime]::FromFileTimeUtc($DeltaFile.time))
    if ($UseRobo -eq 0){ continue }
    Start-Process robocopy.exe -NoNewWindow -Wait -ArgumentList ('"' + $cwd + '\000' + '"' + ' ' + '"' + $cwd + '\' + $ShortFold + '"' + ' ' + $ShortFile + ' /MOV /R:1 /W:1 /NS /NC /NFL /NDL /NP /NJH /NJS')
  }
  [void]$PSFFileStream.Close()
  $null = [IO.Directory]::Delete("000",$True)
}

# =========================
# Run patch
# =========================
Write-Host "Applying PSF patch into $SubFolder ..."
P $WimFile.FullName "msdelta.dll"
Remove-Item $PsfFile.FullName -Force

# =========================
# Prompt to Install
# =========================
# --- Install SSU first if present ---
$SSU = Get-ChildItem $Base -Filter *SSU*.cab | Select-Object -First 1
if ($SSU) {
    Write-Host "Installing Servicing Stack Update: $($SSU.Name)"
    Start-Process dism.exe -ArgumentList "/online /add-package /packagepath:`"$($SSU.FullName)`"" -Wait -NoNewWindow
    Write-Host "SSU installation complete."
} else {
    Write-Host "No SSU CAB found in $Base, skipping SSU install."
}

# --- Prompt to Install LCU ---
$answer = Read-Host "Do you want to install the cumulative update now? (Y/N)"
if ($answer -match '^[Yy]$') {
    Write-Host "Installing LCU via DISM..."
    Start-Process dism.exe -ArgumentList "/online /add-package /packagepath:`"$SubFolder`"" -Wait -NoNewWindow
} else {
    Write-Host "Update prepared in $SubFolder, you can install later with DISM."
}

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N21One said:

Is this the full script?

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N21One said:

The script gives error in function Native($DllFile) and function ApplyDelta($dBuffer,$dFile).

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jen1 said:

I do not recommend automatic extraction for the MSU, as you only need six specific files

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Maxstar said:

I know, but I'm using your script for file sourcing purposes only, just to find manifest files and/or cat-mum pairs without installing the update itself.

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Tekkie Boy said:

No, that's the section that @Maxstar added to the script from @jen1.



I think you should provide more information for @jen1.

I tested the script on my system using build 26200.5761 and it ran without any problems.


Greetings

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N21One said:

Please can you share the full script of your merged version. Thanks.

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Maxstar said:

No, this script is written by @jen1, and in order to avoid violating certain unwritten copyright rules, I will not share a modified script! Also, because you can easily merge the script(s) if you know how it works. And the developer has also indicated that he does not recommend my addition for standard use.

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