CVS commit: src/bin/sh

["Robert Elz" <kre%netbsd.org@localhost>]

Module Name:    src
Committed By:   kre
Date:           Sat May 13 03:26:03 UTC 2017

Modified Files:
        src/bin/sh: eval.c shell.h show.c show.h

Log Message:
The beginnings of the great shell DEBUG (tracing) upgrade of 2017...

First, be aware that the DEBUG spoken of here has nothing whatever to
do with MKDEBUG=true type builds of NetBSD.   The only way to get a
DEBUG shell is to build it yourself manually.

That said, for non-DEBUG shells, this change makes only one slight
(trivial really) difference, which should affect nothing.

Previously some code was defined like ...

function(args)
{
#ifdef DEBUG
        /* function code goes here */
#endif
}

and called like ...

#ifdef DEBUG
        function(params);
#endif

resulting in several empty functions that are never called being
defined in non-DEBUG shells.   Those are now gone.   If you can detect
the difference any way other than using "nm" or similar, I'd be very
surprised...

For DEBUG shells, this introduces a whole new TRACE() setup to use
to assist in debugging the shell.

I have had this locally (uncommitted) for over a year...  it helps.

By itself this change is almost useless, nothing really changes, but
it provides the framework to allow other TRACE() calls to be updated
over time.   This is why I had not committed this earlier, my previous
version required a flag day, with all the shell's internal tracing
being updated a once - which I had done, but that shell version has
bit-rotted so badly now it is almost useless...

Future updates will add the mechanism to allow the new stuff to actually
be used in a productive way, and following that, over time, gradual
conversion of all the shell tracing to the updated form (as required,
or when I am bored...)

The one useful change that we do get now is that the fd that the shell
uses for tracing (which was usually 3, but not any more) is now protected
from user/script interference, like all the other shell inernal fds.

There is no doc (nor will there be) on any of this, if you are not reading
the source code it is useless to you, if you are, you know how it works.


To generate a diff of this commit:
cvs rdiff -u -r1.139 -r1.140 src/bin/sh/eval.c
cvs rdiff -u -r1.20 -r1.21 src/bin/sh/shell.h
cvs rdiff -u -r1.38 -r1.39 src/bin/sh/show.c
cvs rdiff -u -r1.9 -r1.10 src/bin/sh/show.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.