From: Junio C Hamano Date: Wed, 21 Nov 2007 09:11:00 GMT Subject: Re: [PATCH] Fix start_command closing cmd->out/in regardless of cmd->close_out/in Message-ID: <7vmyt8gdzv.fsf@gitster.siamese.dyndns.org> In-Reply-To: <46dff0320711201838g5affba6bo21a8c837b0bef681@mail.gmail.com> "Ping Yin" writes: > On Nov 21, 2007 12:17 AM, Johannes Sixt wrote: > ... >> This way the change is more local without affecting well-tested other callers. > > This way works, but it is a tricky one, not a natural or graceful one. I do not know about "natural". That largely would depend on where one starts thinking about the issues from. But I think an API definition that says "These fds are closed after the call, so if you are going to use them, you can dup() them beforehand" is equally valid, and I suspect that forgetting to dup() is easier to detect than forgetting to close() --- you will notice the former mistake immediately because your read and write say "oops, nobody on the other end" but the latter mistake will result in a hung process. And for that reason, I think it can be called more "graceful". So ... >> Furthermore, I don't think that it's correct to just set the .close_in or >> .close_out flags. This will close the fd only in finish_command(), which can >> be too late: Think again of a writable pipe end that remains open and keeps >> the reader waiting for input that is not going to happen. > > This may happen. However, i have scanned all the git codes using the > auto closing behaviour and i don't discover the problem you mentioned. > So i think it deserves to correct the misbehaviour after carefully > testing. And we can make a clarification for that if necessary. ... I do not necessarily agree that your patch is correcting the misbehaviour.