On Sun, Apr 01, 2012 at 11:53:12AM +0200, Andreas Schwab wrote: > Chet Ramey <chet.ra...@case.edu> writes: > > > On 3/31/12 9:19 AM, Lluís Batlle i Rossell wrote: > >> Hello, > >> > >> I have this script, that I've found to never write "DONE" in my systems, > >> with > >> bash 4.0, 4.1, 4.2.. until 4.2-p20, my last test. > >> > >> However, in irc some people told me it prints DONE for them. If I run the > >> script with > >> bash under 'strace -f', it also prints DONE. > > > > It looks like a simple race condition. I suspect that the scheduler > > arranges things so that the child process ends up exiting between the > > open and the read, but I don't have any real evidence to back it up. > > Note that the opening of the pipe as part of the redirection in the > parent blocks until there is a writer, ie. until the child opens the > pipe. Can this open call return EINTR?
Ah, maybe this is the source trouble. EINTR in open, instead of read. But in this case, even a C program could not be protected against this race other than blocking signals before opening the descriptor. Maybe someone else knows better.
