Mail Archives: djgpp/1997/04/21/21:43:06
Eli Zaretskii wrote:
>
> On Mon, 14 Apr 1997, Christopher Croughton wrote:
>
> > > If you are willing to wait until the child exits, why can't
> > > you just spawn the same program, like so:
> >
> > Try doing it when the bit that does the fork is down in 10 levels
> > of function calls, and depends on gobal variables being set correctly
> > by the time it gets there. In the case of tcsh, that includes all
> > the aliases and local shell variables, not just the environment which
> > is passed to the child.
>
> This problem is only relevant to a program that forks itself. Most
> programs call `execXX' right after forking, which is functionally the
> same as `spawnXX'.
>
> I think the approach that you had in mind (to change the DJGPP startup
> code) is too complex. I can think about two other possibly simpler
> ways of making this happen.
>
> 1) Look how this is done in the DJGPP port of Bash. I don't
> know the answer, and therefore cannot tell how well it suits you, but
> it *does* work.
>
> 2) Create an image of the program with all the variables
> frozen at their values, then invoke that program. That is how the
> Emacs executable is created when you build Emacs, so you can look at
> the Emacs sources (filename unexec.c) to see how this works. In
> Emacs, the image is actually written to a disk file, but going from
> there to a memory move followed by passing the control to that image
> shouldn't be very hard. The `v2loadimage' function (see djlsr201.zip,
> file src/debug/common/v2load.c), used by all DJGPP debuggers, is a
> working example of how an image is loaded and control passed to it.
There is a compiler on Simtel (oxcc1434.zip) which will evaluate (run by
interpreting) your program and then regenerate the source which can
be passed to gcc. This method is much more flexible than the 'imageload'
that is done in emacs etc. Under DOS the compiler runs in a framework
powered by DJGPP V1.12. I wrote this thing a few years ago but have
not gotten much interest so I have not posted any updates. If anyone
is really interested in this style of 'reflective compiler' then I
will do some more fiddling and posting. Please read the DOCs and
respond via e-mail as well as to the group.
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Norman David Culver ndc AT icanect DOT net (954)463-4754
Oxbow Software 1323 SE 17th St. Ft. Lauderdale, FL 33316
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