autoconfig

[byron@netapp.com (Byron Rakitzis)]

Ok, I've been thinking some more about this and I went through
rc's config.h to see what could be done about it all. Here's
a walk through the list of options in config.h, I wanted to see
if I could get rid of most or all of them:

> #define DEFAULTPATH "/usr/ucb", "/usr/bin", "/bin", "."

I think this can be deduced by running /bin/sh as a login shell
with $PATH unset, and snarfing the output of "echo $PATH".

> #define NODIRENT
> #define SVSIGS

Handled by GNU autoconf.

> #define NOCMDARG
> #define DEVFD
> #define TMPDIR "/var/tmp"

I am sorely tempted to remove named pipe support. It never worked
properly. So something is needed to auto-sense the particular
encoding for /dev/fd (systems encode this differently), which I
doubt is supplied by GNU autoconf.

> #define NOLIMITS

Should be handled by autoconf, or can be extended to do so.

> #define NOSIGCLD

Handled by autoconf.

> #define READLINE

Leave this as-is.

> #define NOEXECVE

I think I should bundle my fake execve; it is a very small amount
of code and will only cause extra file opens and the like on an
exec failure, which is out of the "performance loop".

> #define DEFAULTINTERP "/bin/sh"

Ditto, this should just be a standard feature.

> #define PROTECT_ENV

Given that every /bin/sh I have tried croaks on rc-native environment
variable representation in some way or other, PROTECT_ENV should
be the only method for encoding env. variable names.

> #define NOECHO

rc's echo should be built in.

> #define NOJOB

Does anyone use this? It forces sh-like semantics for backgrounding.
Why should it be an option? I haven't found a use for it, but I think
I put it in in self-defense early on.

My conclusion: It seems that rc + an autoconfig script could take
out all the configuration options. I don't see the point of going
with Posix, then.