On 31 January 2013 17:45, Paul Eggert <[email protected]> wrote:
> On 01/31/13 05:09, Reuben Thomas wrote:
> > Looks to me as though the "fi" should come immediately after
> "REPLACE_OPENPTY=1", not at the end of the stanza. Does that seem right?
> >
>
> Close, but not quite right, as the containing 'if'
> checks only that openpty has been declared, not that
> it exists. Can you fix that?
>
The whole file assumes that functions exist if they have been declared, and
state this assumption (see also gl_FUNC_FORKPTY), so that's not something I
want to fix right now.
I still don't understand what the answer to my original question is, i.e.
how do I detect in my C code whether I've actually got some openpty
implementation? As far as I can see from pty.m4, HAVE_OPENPTY is only
defined if the system actually has the function, and REPLACE_OPENPTY is
only defined if the system declares the function but not correctly. If the
system utterly lacks openpty, but has _getpty and posix_openpt, then a
replacement will be built, but no macro will be set.
It seems to me that HAVE_OPENPTY should end up set to 1 in any of these
three cases, i.e. in both arms of the outermost if, provided that the
required functions are found. Further, it seems there's another bug: the
two arms of the outermost if should not be mutually exclusive, because if
you come out of the top branch with REPLACE_OPENPTY=1 , then you still need
to run the check in the bottom branch to make sure you can actually build
the replacement. Otherwise, if you're on a system that declares openpty,
but either non-const or without an implementation, and also lacks _getpty
and/or posix_openpt, then you'll end up with REPLACE_OPENPTY=1 incorrectly.
Again, some feedback on my analysis would be helpful. I believe that if
it's correct, the solution is pretty simple, so here it is, to make the
foregoing more concrete:
if test $ac_cv_have_decl_openpty = yes; then
...
if test $gl_cv_func_openpty_const = yes; then
HAVE_OPENPTY=1
end
fi
fi
if test $gl_cv_func_openpty_const != yes; then
dnl We need gnulib's openpty.
dnl Prerequisites of lib/openpty.c in this case.
AC_CHECK_FUNCS([_getpty posix_openpt], [HAVE_OPENPTY=1;
REPLACE_OPENPTY=1], [HAVE_OPENPTY=0; REPLACE_OPENPTY=0])
fi
if test $HAVE_OPENPTY = 1; then
AC_DEFINE([HAVE_OPENPTY], [1],
[Define to 1 if the system has the 'openpty' function.])
fi
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