Date: Sat, 17 Oct 2009 12:46:37 -0400 From: "Mikhail T." <mi+thun@aldan.algebra.com> To: stable@FreeBSD.org Subject: Can close-ing a pipe trigger a SIGPIPE? Message-ID: <4AD9F4ED.2050002@aldan.algebra.com>
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Hello!
I'm investigating a problem caused by (what seems like a spurious)
SIGPIPE. The program creates a child process using pipe, exchanges a few
messages with the child (via write and read) and closes the pipe.
Some times -- in about 60% of the cases -- this causes a SIGPIPE to be
delivered to the parent...
Now, it is quite possible for the child to have already exited by the
time the parent closes its end of the pipe -- but why should that cause
a SIGPIPE, unless the parent tries to write something to the widowed
pipe, which it does not?
>From pipe(2):
A pipe that has had an end closed is considered widowed. Writing
on such
a pipe causes the writing process to receive a SIGPIPE signal.
There is no other mention of SIGPIPE in that manual page...
I set SIGPIPE on ignore around the pipe-closing as a work-around, but I
think, this is a bug...
The thing is part of TclX' self-test (test signal-3.0) -- and it was not
dying from SIGPIPE before the FreeBSD-7.x, as far as I can remember...
It still seems to be fine on Linux...
Have there been any changes in this area in FreeBSD? Thanks!
-mi
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