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Re: Opinions solicted for changes to tty names in 1.7.10


On 15 June 2011 21:52, Christopher Faylor wrote:
> On Wed, Jun 15, 2011 at 09:46:24PM +0100, Andy Koppe wrote:
>>On 15 June 2011 15:55, Christopher Faylor wrote:
>>> On Wed, Jun 15, 2011 at 01:28:55PM +0100, Andy Koppe wrote:
>>>>On 14 June 2011 21:36, Christopher Faylor wrote:
>>>>> After some discussion with Corinna, I'm thinking about making a change to
>>>>> the tty naming in Cygwin as part of the removal of CYGWIN=tty.
>>>>>
>>>>> (In case you haven't noticed, CYGWIN=tty, is no longer supported in
>>>>> snapshots. ??If you do have the tty option set you get one warning per
>>>>> session telling you to unset it.)
>>>>>
>>>>> Since the only thing using Cygwin's "tty layer" will now be ptys, I'd
>>>>> like to rename /dev/ttyN to /dev/ptyN. ??I've already added /dev/consN
>>>>> support for consoles but I'd like to change that so that consoles are
>>>>> represented as /dev/ttyN instead.
>>>>
>>>>Makes plenty of sense.
>>>>
>>>>The only concern I see is that BSD PTYs (as previously used on Linux
>>>>as well, IIRC) are called "pty[p-za-e][0-9a-f]" on the master side,
>>>>whereas they're "tty[p-za-e][0-9a-f]" on the slave side. Therefore
>>>>calling the slave side "ptyN" could conceivably cause issues.
>>>>
>>>>Is the Unix98 scheme ("/dev/pts/N") that's used on Linux these days
>>>>out of the question?
>>>
>>> No. ??I considered that but adding an arbitrary directory structure under
>>> out /dev kludge seemed wrong. ??I would prefer to make it look more like
>>> Linux though. ??The man reason why I didn't implement that is that I
>>> thought someone would report that "ls /dev/pts" doesn't work
>>
>>Good point. Unlike "ls /dev/pty*", it would actually be useful as it's
>>supposed to contain the currently used ptys.
>>
>>> not that it couldn't be made to work.
>>
>>That would be nice.
>
> I agree. ÂSo, I guess I'll look into what it would take to implement
> that and hold off the renaming for now.
>
>>The terminal is supposed to cut off all of "/dev/tty", especially as
>>Cygwin's ut_id is only 2 chars, whereas Linux's is 4.
>
> Oh right. ÂI knew that.

Hmm, the two-character ut_id would actually be a problem with Unix98
ptys, because according to Linux's 'man utmp' it's supposed to be 'p'
followed by the pts number there. This would only allow for 10 ptys.

How about going with the BSD scheme as previously used on Linux?
Should be much less work than Unix98 ptys as well.

consoles: ttyN
pty masters: /dev/pty[p-za-e][0-9a-f]
pty slaves: /dev/tty[p-za-e][0-9a-f]

The [p-za-e][0-9a-f] encoding allows for up to 256 pseudo terminal
pairs and fits into ut_id.

Andy


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