Re: [Qemu-devel] [PATCH for-1.5] portability: pty.h is glibc-specific

[Eric Blake <eblake@redhat.com>]

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On 05/14/2013 01:28 PM, Laszlo Ersek wrote:

> Not to argue with this, just a general note: most of whatever is
> portable from the terminal IO interfaces belongs into <termios.h> indeed.
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/termios.h.html
> 
> Traditionally nonportable stuff related to pty allocation and
> master-slave pairing has been "recently" standardized as well (as in,
> SUSv3 / UNIX 03):
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_openpt.html
> 
> (+grantpt, ptsname, unlockpt; they seem to date back to SUSv1 / UNIX 95)
> 
> CC'ing Eric for the obligatory POSIX sanity check... :)

Looks accurate.

Still missing from POSIX is ptsname_r, although it might appear in the
next revision ("Issue 8") in a few years:
http://austingroupbugs.net/view.php?id=508

which means right now, POSIX has no thread-safe mechanism for
determining the slave name after opening a master pty.

Personally, I find the high-level BSD openpty() interface a lot nicer to
use than the POSIX posix_openpt()/grantpt()/unlockpt()/ptsname()
sequence, but it may come with its own pitfalls since it is not
standardized (yet).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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