[Info-vax] Questions about sys$cli()

[Stephen Hoffman]

On 2019-06-29 22:42:48 +0000, Simon Clubley said:

> Is this structure some artifact from an earlier version of VMS and is 
> now obsolete, or does it map to a DCL memory area which I have not 
> found yet ?

Wouldn't surprise me to learn that this is just another oddity of an 
API-specific descriptor parser implementation.

There have been and remain some... poorly-considered... APIs found 
within OpenVMS, whether from the sys$cli era or from subsequent eras.

Among those APIs I've had tussles with include the exe$getspi API 
underneath MONITOR—I posted I_SPI.C for that—and that API eventually 
begat the sys$getrmi system service, and there's also the I2C 
interface—which has yet to acquire a documented API.  There are others.

These APIs are usually not (originally) intended for user use, and 
there can be any number of latent problems for the callers to discover 
and/or to navigate.  Beyond incomplete or no published documentation, 
that is.

As for calling sys$cli, here's a (previously-posted) link to some 
published OpenVMS documentation (page 11ff):
ftp://bitsavers.informatik.uni-stuttgart.de/www.computer.museum.uq.edu.au/pdf/AA-D015B-TE%20VAX-VMS%20Release%20Notes.pdf 

Yes, parts of sys$cli were documented APIs.

Among other example sys$cli calls, also see:
https://groups.google.com/d/msg/comp.os.vms/sH7ZZQqNHWw/4x3rXatCBAAJ

Given the obsolete-features manual was itself and rather hilariously 
declared obsolete, it's anybody's guess which OpenVMS features and APIs 
are actually considered obsolete and/or undocumented.

Poking at undocumented APIs is pretty popular with some folks. For 
various reasons. On some platforms, undocumented or unsupported APIs 
have been fertile ground for finding security exploits.


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