poka.sh

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MST

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MSI Transform Preview.

At a glance
Purpose A Windows Installer transform: changes to an MSI database, stored as streams in a compound file.
Extensions .mst
Poka parser poka-mst
Viewer poka-tree-viewer
Depth tier Parser with a shared viewer (see Depth tiers)
Breadth tier B4 Summary (see Breadth tiers)

How much Poka reads

B4 Summary. The container and metadata are read and summarised (counts, properties, structure), but the main content is not rendered.

Confidence: medium (the reviewer read the code). Basis: Reviewed 2026-10-26: read parsers/poka-mst/src/main.rs (640 lines) and plugin.json. No unit tests or tests/samples.rs; the corpus has psmsi_Example.mst, read by no test. Covers .mst. The tree reads the compound file and lists every storage and stream, with stream names decoded and the transform streams (_TransformInfo, _Tables, _Columns, _StringData, _StringPool, _Validation, SummaryInformation) named, plus counts. Judgement: B4: the transform's structure is listed, but none of its changes are decoded.

What Poka does not read

  • The changed rows, columns and tables are not decoded
  • The summary information (base and target product codes and versions) is not decoded
  • Only the first 300 streams are listed; files over 64 MiB are cut

Libraries

Libraries Poka uses or has assessed for this format, with the status, licence and language the registry records.

  • msitools (libmsi) (candidate; LGPL-2.1-or-later; C/Vala; https://gitlab.gnome.org/GNOME/msitools) — libmsi source (table.c) contains msi_table_apply_transform / msi_table_load_transform; the licence is taken from that source file header, as no standalone LICENSE page could be loaded; derived from Wine's msi.dll
  • WixToolset.Dtf.WindowsInstaller (WiX DTF) (candidate; MS-RL; C#/.NET; https://packages.nuget.org/packages/WixToolset.Dtf.WindowsInstaller) — Managed Windows Installer API with Database.ApplyTransform; licence from the WiX repo LICENSE.TXT, and the NuGet page also requires adherence to the WiX Open Source Maintenance Fee EULA; probably wraps native msi.dll, so likely Windows-only (unconfirmed)

Sources

  • parsers/poka-mst/src/main.rs
  • parsers/poka-mst/plugin.json