Subtask support for `task` data type

[wf34]

Some people (e.g. here [no relation to blog author]) used libpff to process their Microsoft ToDo task archives. These archives come in PST files from Microsoft Outlook (source).

I attempted the same, and run into a couple of issues:

• It seems that python bindings don't support the task type. I've skimmed through source code, my impression seems correct, as it looks lke the python bindings export "tasks" as "messages". This is suboptimal: Yes, I can still read task's title and body when it's interpreted as if it were a message, but the due dates, completion statuses and lists of substasks are ignored that away.

• It looked like libpff's C API had the full support of tasks, so I just run pffexport and inspected the output. This way is better, as due datas and completion statuses are parsed, but subtasks are still not handled by pff.

Is it a known issue?
I'm not 100% positive, that my PST which got exported from MS Outlook actually preserves these subtasks, but I'll try inspecting the matter further soon, and will inform here.

[wf34]

Some progress. I run pffexport in -d mode ( dumps each entry as a whole into its dedicated ItemValues.txt).
The substask are apparently there in the data, thus the support for them can be added:

Set:				0
Entry:				110
Entry type:			0x00008099
Value type:			0x0000001f
Maps to entry:			IOpenTypedFacet.Com_Microsoft_Todo_Subtasks
Value:

[wf34]

I don't know, what place does this have in libpff, but I've figured out the encoding of Com_Microsoft_Todo_Subtasks.
The sequence of hex values that follows in this exported file ItemValues.txt can be decoded into a standard JSON in following way:

xxd -r -p subtask.txt | iconv -f UTF-16LE -t UTF-8

NB: I copy-pasted the hexdump part after the Value: line into a standalone subtask.txt for demonstration