MsiClient PowerShell Module

Based on my previous post, I created a small project on my github and adjusted existing codebase to provide a simplistic PowerShell module. The code has been reorganized into proper units with exported functions. Here is a sample usage:

$Header = @"
  TABLE {border: 1px solid gray collapse; }
  TH { border: 1px solid gray; padding: 6px 4px; background-color: #eaeaea; }
  TD { border: 1px solid gray; padding: 4px; }
Import-Module MsiClient
Get-MsiClientPackage | where { $_.Publisher -contains 'Microsoft Corporation' } | sort-object -Property ProductName | ConvertTo-Html -Property ProductCode,PackageName,ProductName,VersionString,Language,Publisher -Head $Header | Out-File c:\temp\test.html

The above snippet produces a HTML based report, showing all Microsoft products available on the current system.

There are still lots of TODOs, which I am going to cover soon, for example:

  • More methods supported (install, uninstall, repair etc.)
  • Better exception handling
  • Support for -WhatIf and -Confirm switches

In any case, my design goal is to keep the syntax similar to functions available in the AppVClient module, so that ideally for basic scenarios they have a 1-1 mapping in the MSI counterpart.

Link to my guthub (the project is licensed under MIT):

Enumerating installed MSI products with PowerShell and msi.dll

If you were ever wondering how to properly read the list of installed MSI software, then two popular choices are available:

  • Querying uninstall registry keys (HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall), filtering out-non MSI entries and outputting the rest
  • Using Win32_Product from WMI

They both have their pros and cons. Querying registry is straightforward on its own, but requires awkward manipulations and accessing the data which is actually backing the Add/Remove Applet, not necessarily the Windows Installer API which uses its own complex registration. Additionally it may not work correctly with different installation context (user/machine) and you may have to query two places to get both x86 and x64 installations on a x64 system.

On the other hand, while WMI query is also pretty straightforward (seeĀ, it has a really big drawback. Running it is painfully slow, because Windows Installer checks integrity of each entry and triggers appropriate action (for example repair) if necessary.

So to have a solution which is both fast, reliable and without any side-effects, you may go for a third solution which is more complex, but once setup can be reused not only for querying but for a whole management of MSI-based installations. And so this blog today will be about P/invoking native msi.dll to get results returned by the true Windows Installer API.

This post may be too technical if you have never programmed in C/C++ or C#. If you just want the results without understanding how to implement them on your own, scroll to the bottom, the full content of the PowerShell script is there.
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Files not installed when applying a Minor Upgrade and how to troubleshoot it

While analyzing one of customer issues reported to me, I came accross an interesting problem which – having prior knowledge how it works – would be solved in minutes, not in hours and days as it really took.

The problem

The customer reported that an MSP patch created by RayPack works fine, but not really up to his expectations. While being considerably smaller than a full MSI upgrade, the installation took a while because the previous version must have been uninstalled and installed again in the background. This is basically the idea how major upgrades are working, and the customer wanted to switch to a typical patching, which (depending on conditions) would mean going for a small update or a minor update.

We suggested to him that while usually not recommended in packaging projects, minor upgrades are different from major upgrades that they must not change ProductCode, aside of some other limitations. The customer tried it anyway and reported that our suggestion initially helped, only to report some minutes later that it actually hadn’t. The new version of product had been apparently installed (and visible in ARP), but the files were not updated – new files were still missing, binary changes were not applied etc. There were no errors during update, the msiexec exit code was also fine.

Another issue was, that after installing the patch, self-repair stopped worked for random components. Removing certain key path resources triggered repair, while for others it did not work. Weird.

Analysis + findings

Our analysis indicated that it was not actually a problem with the patch itself, but more like with the way Minor Upgrades are working, and thereof the problem could be easily reproduced by installing the second MSI containing a minor upgrade with a command line:

msiexec /i <path> REINSTALLMODE=vamus REINSTALL=all /qb

(note: vamusis non-standard, but was chosen for troubleshooting to also overwrite files in the same version). It is important to indicate that the cached MSI has to be recached from source (thus v in the reinstall mode), otherwise you obviously can’t install an MSI as minor upgrade.

We don’t do that many minor upgrades, but enough to be aware of certain limitations, including that names of MSIs must be the same (so that Product2.0.msi cannot do a minor upgrade of Product1.0.msi etc.), the feature trees must remain unchanged, some other conditions apply (more on msdn sites).

If you ever encounter a problem like that, have some time saved by this ultimate troubleshooting:
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