GNU bug report logs - #12040
24.1.50; `term' hangs on FreeBSD 10.0-CURRENT without pty(4)

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jan Beich <jbeich <at> tormail.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.1.50; `term' hangs on FreeBSD 10.0-CURRENT without pty(4)
Date: Mon, 23 Jul 2012 23:31:27 +1200

[Message part 1 (text/plain, inline)]

Starting with FreeBSD 8.0-RELEASE the system uses new tty layer that no
longer supports old style pseudo ttys *unless* pty(4) kernel module is
loaded. However, pty(4) device is still included in GENERIC kernel on
all releases except 10.0-CURRENT (removed in r233271).

  $ emacs -Q
  M-x term
  <hangs here>

  $ sudo kldload pty
  [try again]

A few ways to solve this:
- use openpty() in -lutil like darwin
- add use posix_openpt() support

http://svn.freebsd.org/changeset/base/233271
https://pub.allbsd.org/FreeBSD-snapshots/ # for testing, seems to be down atm

[openpty.diff (text/x-patch, attachment)]

[posix_openpt.diff (text/x-patch, attachment)]

Message #12 received at 12040 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Jan Beich <jbeich <at> tormail.org>
Cc: 12040 <at> debbugs.gnu.org
Subject: Re: bug#12040: 24.1.50;
	`term' hangs on FreeBSD 10.0-CURRENT without pty(4)
Date: Thu, 16 Aug 2012 02:45:30 -0400

Jan Beich wrote:

> A few ways to solve this:
> - use openpty() in -lutil like darwin
> - add use posix_openpt() support

Thanks for the patches.
Do you (or anyone else) have a feeling for which is the best?
As written the posix_openpt one changes the behaviour on gnu-linux
platforms to use posix_openpt instead of getpt.

Message #15 received at 12040 <at> debbugs.gnu.org (full text, mbox):

From: Jan Beich <jbeich <at> tormail.org>
To: Glenn Morris <rgm <at> gnu.org>
Cc: 12040 <at> debbugs.gnu.org, Robert Millan <rmh <at> freebsd.org>
Subject: Re: bug#12040: 24.1.50;
	`term' hangs on FreeBSD 10.0-CURRENT without pty(4)
Date: Thu, 16 Aug 2012 05:10:03 -0500

(cc'ing Robert in case I misread glibc code)

Glenn Morris <rgm <at> gnu.org> writes:

> Jan Beich wrote:
>
>> A few ways to solve this:
>> - use openpty() in -lutil like darwin
>> - add use posix_openpt() support
>
> Thanks for the patches.
> Do you (or anyone else) have a feeling for which is the best?

I'd go with less wrappers - posix_openpt(). And also use it on netbsd,
dragonfly and probably darwin.

openpty() is implemented via posix_openpt() in libutil on recent freebsd.

posix_openpt() is a syscall on (k)freebsd. And /dev/ptmx only exists if
pty(4) is loaded, not sure how it affects binaries under linuxulator.

> As written the posix_openpt one changes the behaviour on gnu-linux
> platforms to use posix_openpt instead of getpt.

In glibc/linux case getpt() is implemented via posix_openpt():

  // sysdeps/unix/sysv/linux/getpt.c
  int
  __getpt (void)
  {
    int fd = __posix_openpt (O_RDWR);
    if (fd == -1)
      fd = __bsd_getpt ();
    return fd;
  }

In glibc/kfreebsd case getpt() iterates over /dev/ptyXX which won't work
without pty(4) in kernel.

Message #20 received at 12040-done <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: 12040-done <at> debbugs.gnu.org
Subject: Re: bug#12040: 24.1.50;
	`term' hangs on FreeBSD 10.0-CURRENT without pty(4)
Date: Fri, 17 Aug 2012 03:21:49 -0400

Version: 24.3

Thanks, I'm convinced. I installed the posix_openpt change for freebsd
and netbsd to the trunk, currently expected to be released as 24.3. I
left darwin alone for the time being.

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