[Crash-utility] Miscellaneous fixes/enhancements to crash 4.0-2.10(fwd)

[Dave Anderson]

Castor Fu wrote:

> On Thu, 10 Nov 2005, Dave Anderson wrote:
>
> >> I also did not feel comfortable accepting the extension-keyword
> >> stuff.  While I do recognize that it would be useful to be
> >> able to dynamically determine what extension modules to load,
> >> I don't feel the extend command should be encumbered with the
> >> job, but rather such an implementation-specific chore should
> >> be handled by an instance of extension library code.
> >>
> >> For that reason I exported both the load_extension() and
> >> unload_extension() functions so that extension library code
> >> could use them to in turn load other extension libraries.
> >>
> >> The call to load_extension() could be made from either the
> >> _init() function or from an extension command.  At those
> >> points in time, the "first" extension library will have all
> >> the information (kernel version, crash version, dumpfile,
> >> etc.) at its disposal, and then can make the decision as to
> >> what additional libraries to load.
>
> Implementing this, I realized that the for this scheme to work,
> if I want to access things like the crash version, the 'pc'
> structure will have to remain the same.  Perhaps a small
> set of these functions can be exported to reduce  the dependencies
> of such a loader on defs.h?
>
> The minimal expectation would be something which would export
>
>      pc->program_version
>
> If pc->curcmd were exported, that would also remove dependencies
> on calling cmd_usage.
>

I do try my best to not muck with the basic data structures, and if changed,
to add the new struff onto the end of the data structure, so even if a module
were built with an older version, its dependencies would still be in place.
And with respect to the program_context structure specifically, I cannot
even remember the last time that it changed.  We can always put a
moratorium on the data structure to enforce the "only-add-to-the-end"
rule.  Or if you feel it's necessary, come up with a mechanism for
exporting stuff generically for extensions, come up with something
that we can put in extensions.c.

Dave