On Wed, Feb 08, 2012 at 11:37:45AM -0500, Nick Mathewson wrote: > On Tue, Feb 7, 2012 at 1:47 PM, Nicholas Marriott > <nicholas.marri...@gmail.com> wrote: > > Forwarding this message to ML at Nick's request... > > > > Hi > > > > You may remember a few months ago you fixed a problem with kqueue and > > EPIPE on pipes - I backported this fix to 1.4 and recently applied it to > > OpenBSD. > > > > However, this is causing problems with Google Chrome. From what we can > > gather it appears the problem is with EBADF - when kqueue returns EBADF > > for an fd, libevent fires the read callback, same as for EPIPE. This > > makes Chrome segfault somewhere in a huge mess of C++ that I can't > > figure my way through. > > Hm. So IIRC, we first added that EBADF in, it was (supposedly) > because some kqueue implementations produced EBADF in response to one > side of a pipe being closed while we were watching the other with > kqueue. > > Do we know what platform or platforms this might have been? I'm not > convinced atm that it's a real thing. I've attached a small test > program that tries closing the read and the write side of a pipe, both > before and after the point where it is added to the kqueue. Can we > find any platform where it says "bad file descriptor"? If not, your > fix would indeed seem to be the easy way around the present issue.
Well, I guess for a full fix things should perhaps be made consistent. Every backend seems to behave differently when adding a closed file descriptor. This is on Linux: $ ./evtestx [warn] Epoll ADD(5) on fd 3 failed. Old events were 0; read change was 1 (add); write change was 1 (add): Bad file descriptor evtestx: event_add: Bad file descriptor $ EVENT_NOEPOLL=1 ./evtestx ^C $ EVENT_NOEPOLL=1 EVENT_NOPOLL=1 ./evtestx [warn] select: Bad file descriptor evtestx: event_dispatch: Bad file descriptor So currently: kqueue fires an event, select exits the event loop, poll does nothing, epoll causes event_add to fail. My change will make kqueue behave like it did before and do nothing - the same as poll. Whether epoll and select also need to be fixed I'm not sure. *********************************************************************** To unsubscribe, send an e-mail to majord...@freehaven.net with unsubscribe libevent-users in the body.
