> From: Paolo Bonzini [mailto:paolo.bonzini@xxxxxxxxx] On Behalf Of Paolo Bonzini > Sent: Thursday, September 06, 2012 4:32 PM > To: Joachim Schmitz > Cc: git@xxxxxxxxxxxxxxx; 'Junio C Hamano'; 'Erik Faye-Lund'; bug-gnulib@xxxxxxx; rsbecker@xxxxxxxxxxxxx > Subject: Re: poll() emulation in git > > Il 06/09/2012 16:02, Joachim Schmitz ha scritto: > > > > But is there something that could be done to make git work even without poll()? > > It is used in 5 places: > > > > $ grep -n poll\( *.c */*.c > > credential-cache--daemon.c:175: if (poll(&pfd, 1, 1000 * wakeup) < 0) { > > daemon.c:1018: if (poll(pfd, socklist->nr, -1) < 0) { > > help.c:361: poll(NULL, 0, autocorrect * 100); > > upload-pack.c:232: if (poll(pfd, pollsize, -1) < 0) { > > builtin/upload-archive.c:125: if (poll(pfd, 2, -1) < 0) { > > > > Don't quite understand why in help.c it has that NULL, which should always result in an EFAULT and other than that basically is a > > NOP (at least in the poll() emulation)? Seems a usleep(autocorrect * 100) is meant to happen here instead? > > So I think here a poll() isn't needed at all. But also the 'broken' one shouldn't harm too much. > > Yes, it's an usleep(autocorrect * 100000) basically (poll takes > milliseconds, not micro). OK, it is _supposed_ to do this usleep(), but is does not, as poll() returns early with EFAULT in this case: /* EFAULT is not necessary to implement, but let's do it in the simplest case. */ if (!pfd) { errno = EFAULT; return -1; } poll() is doing this before calling select(), so won't sleep. So there's a bug in {gnulib|git}'s poll(), right? > > ... > > # else > > char data[64]; > > r = recv (fd, data, sizeof (data), MSG_PEEK); > > socket_errno = (r < 0) ? errno : 0; > > # endif > > if (r == 0) > > happened |= POLLHUP; > > > > /* If the event happened on an unconnected server socket, > > that's fine. */ > > else if (r > 0 || ( /* (r == -1) && */ socket_errno == ENOTCONN)) > > happened |= (POLLIN | POLLRDNORM) & sought; > > > > /* Distinguish hung-up sockets from other errors. */ > > else if (socket_errno == ESHUTDOWN || socket_errno == ECONNRESET > > || socket_errno == ECONNABORTED || socket_errno == ENETRESET) > > happened |= POLLHUP; > > > > #ifdef __TANDEM /* as we can't recv(...,MSG_PEEK) on a non-socket */ > > else if (socket_errno == ENOTSOCK) > > happened |= (POLLIN | POLLRDNORM) & sought; > > #endif > > else > > happened |= POLLERR; > > } > > ... > > > > We won't detect POLLHUP that way I think. However it seems to work, we've been able to clone, push, pull, branch that way with > > NonStop being the (ssh-)server, something that didn't work at all without that hack (and yes, I believe it is just that). > > Someone in for a cleaner way of managing this? > > I suppose it works to always handle ENOTSOCK that way, even on > non-__TANDEM systems. So you think this is a clean way of dealing with it? Bye, Jojo -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html