flua: add posix.unistd.dup2()

[ifreund_freebsdfoundation.org]

Summary

Sponsored by: The FreeBSD Foundation

[imp]

libexec/flua/modules/lposix.c

175

why doesn't this require a goto err too?

[ifreund_freebsdfoundation.org]

libexec/flua/modules/lposix.c

175

This function raises a lua error on failure and does not return.

Internally it longjmps away to somewhere else in the lua VM and either invokes an error handler if in a pcall() context or prints a stack trace and exits.

The luaL_checkinteger calls below behave the same.

[emaste]

libexec/flua/modules/lposix.c

174

We seem to have a number of different styles for the arg and extramsg args of luaL_argcheck

• _exit narg == 1, 1
• basename narg > 0, 1
• chmod n == 2, n > 2 ? 3 : n
• chown n > 1, n

some include the function (close takes exactly one argument (fd)) while some do not (at least one argument required).

Independent of this change we could do a pass to rationalize these

[ifreund_freebsdfoundation.org]

libexec/flua/modules/lposix.c

174

I opened D50273 to clean this up.

[ifreund_freebsdfoundation.org]

My git branch for this patch stack is here: https://github.com/ifreund/freebsd-src/commits/bsdinstall-pkgbase-components/

[ifreund_freebsdfoundation.org]

Use new enforce_max_args() function from D50273

[emaste]

As an aside while MFCing some flua work I (re)discovered 1f31e00e19f9e24d4c891a24973e08a027c4f71c

[ifreund_freebsdfoundation.org]

In D50176#1147472, @emaste wrote:

As an aside while MFCing some flua work I (re)discovered 1f31e00e19f9e24d4c891a24973e08a027c4f71c

Interesting, I wasn't aware of fbsd.exec. Unfortunately it doesn't look flexible enough to support the bsddialog use-case as it lacks a way to capture stderr output.