On Sat, Oct 23, 2010 at 10:51:38PM -0400, Ken Brown wrote: >On 10/20/2010 4:32 PM, Christopher Faylor wrote: >> On Wed, Oct 20, 2010 at 08:25:37PM +0100, Andy Koppe wrote: >>> On 20 October 2010 13:20, Andy Koppe wrote: >>>>> Corinna made tcgetpgrp return 0 instead of -1 in some circumstances >>>>> (see http://www.cygwin.com/ml/cygwin-patches/2009-q4/msg00045.html) >>>>> because she saw Linux doing that. ??But when I run Corinna's test on >>>>> my Linux system, I get -1 where she got 0. ??So not all Linuxes agree >>>>> on what tcgetpgrp should do. >>>> >>>> Hmm, Corinna's test calls tcgetpgrp(master) in the parent only before >>>> the child is forked and after it exited, so it's correct to report that >>>> there's no foreground process. >>>> >>>> I wonder which Linux it was that returned 0 in case of failure. I've >>>> tried it on a recent Opensuse, an old Redhat with a 2.6.9 kernel, and >>>> also a Debian with a 2.4 kernel, and got -1 on all of those. >>> >>> Actually I'd only tried my test on all three systems, whereas I'd tried >>> Corinna's only on the old Redhat, where it did print -1 for failure. >>> On the 2.4 system it can't open /dev/ptmx, whereas on the Opensuse with >>> 2.6.34 I do get the results Corinna reported, including 0 on the master >>> side of the pty when enquiring from the parent. (Process 0 is the >>> startup process, so I guess that makes some sense.) >>> >>> To bring my ramblings to some sort of conclusion, here's a slightly >>> amended version of Corinna's test that checks the master side from the >>> parent process before, *during* and after the child process: >> >> FYI, I'm sticking with the test case that I first posted several days >> ago and which has been cruelly ignored ever since. I've been slowly >> modifying it for the last several days. >> >> I think I'm seeing some pattern to the way Linux handles this and I should >> be able to make Cygwin work the same way. > >This seems to be fixed in the latest snapshot, as far as emacs is >concerned. I no longer see any difference between Cygwin and Linux >there. I also get the expected results when I run the test cases that >Andy posted. But when I run the original test case that you posted in > > http://cygwin.com/ml/cygwin/2010-10/msg00395.html > >I'm getting strange behavior. I ran it with no argument, getting > >0 = tcgetpgrp(4) >0 = ioctl(fd, TIOCGPGRP, &pid), pid = 0 > >but then the terminal seemed to hang, and I didn't get a new prompt. I >tried this both in mintty and xterm.
I think this falls nicely into the cruelly ignored comment above since I can get my test case to hang on a Windows 7 system prior to the inclusion of any of my recent patches. I'll fix it though. cgf -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
