> I note that the new IO::Tty is "based on ideas from openssh and
> Xemacs."Any ideas from Libes' original Expect in there? Have the
> openssh and Xemacs
> guys figured out a better way than he did or did they just borrow
> from his method? How do all these different approaches compare?
>
> I'm just eaten up with curiosity. :)
Then you need a speedy answer! :-)
For pty allocation, I used ideas from openssh and Xemacs as they have a
more modern approach. A lot of systems have incorporated some kind of
cloning device in the meantime that weren't there when Tcl/Expect was
developed. I concentrated on an idea from Xemacs, namely just figuring
out what possibilities (libs/devices) are there and then trying all of
them in order until one succeeds, the last one being the standard BSD-
style technique of opening all /dev/pty*s one after another until an
open succeeds.
I collected several methods of allocating a pty from several sources.
These are:
openpty()
_getpty()
getpt()
/dev/ptmx
/dev/ptym/clone
/dev/ptc
/dev/ptmx_bsd
If anybody knows about other methods, please let me know.
Now what could be a problem is the pty setup: I use grantpt() and
unlockpt() and push appropriate stream modules via ioctl, but there
could be others necessary, esp. on older systems. The problem is that
I can only rely on information in manpages etc. that I look up via
Google, so I'm flying by instruments, pestering clients to get test
results.
What I used from Tcl/Expect was the method how spawn() works, namely
using pipes to synchronize the parent with the forked child until the
child has set up the pty, passing up a possible exec() error on the
fly. Quite nifty!
Any more questions?
Roland
--
RGi...@cp...
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