I just asked the AI to structure my text: the result shows me that I still have a way to go to write a text that is pleasant to read. I am sharing with you the version restructured by the AI.
Motivation
When you retire, you need to keep yourself busy. For me, that means experimenting with WimgApi.dll—even if I haven’t managed to convince my wife of its charm.
I’ve long wanted to write a PowerShell script to explore the contents of a WIM file using Microsoft’s WimgApi.dll. This week’s exercise: could I extract a file contained in a WIM image?
Of course, there are existing programs that do this. But using them doesn’t teach me anything about my own abilities. At 70, I believe in keeping the neurons active through learning and experimentation. With patience and step by step progress, I achieved my goal.
Learning Process
Working with WimgApi.dll proved laborious. To make progress, two resources were essential:
- The official API documentation from Microsoft.
- The header file WimgApi.h, which provides the formal definitions and constants.
C:\Program Files (x86)\Windows Kits\10\Assessment and Deployment Kit\Deployment Tools\SDKs\Wimgapi\Include\wimgapi.h
Microsoft Docs – WIM API (Windows 11)
https://learn.microsoft.com/en-us/windo ... windows-11
ManagedWimgApi project on GitHub
https://github.com/jeffkl/ManagedWimgAp ... /wimgapi.h
WIM file format documentation (libyal)
https://github.com/libyal/assorted/blob ... t.asciidoc
Legacy MSDN documentation (Vista)
https://learn.microsoft.com/en-us/previ ... dfrom=MSDN
Microsoft download page (Wim format)
https://www.microsoft.com/en-my/downloa ... x?id=13096
Key Challenges
Finding correct API signatures for C# Early references were for Windows 7/8, not Windows 10/11. Mixing them led to incompatibilities—parameters and handle positions differ between versions.
Understanding API sequences For example, you must set a temporary directory before opening a WIM image object. Without it, subsequent calls fail with error 203 (“bad environment”).
Interop work Writing the API declarations in C#, then adapting them for PowerShell. This mechanical work is made easier with AI assistance.
Remarks
This script is not final—it’s a presentation of experiments.
The WIM filename could be passed as a parameter, though I usually copy/paste snippets directly into the console.
TODO: verify proper release of handles and memory blocks.
Extracting a file requires an administrator console.
I added output about ReparsePoints, a topic that interests me. My current understanding: NTFS hardlinks (e.g., WinSxS) are unrelated to ISO size optimization (CDFS). Corrections welcome.
Conclusion
This exercise was both a technical challenge and mental gymnastics. I hope reading the script inspires you to modify it, improve it, and adapt it to your own needs.
a picture:
- Wim3.png (283.73 KiB) Viewed 17203 times
