SIGEPIPE after update to 8.1-RC2

[Kostik Belousov]

On Sun, Jul 18, 2010 at 12:11:50AM +0200, Jilles Tjoelker wrote:
> On Sat, Jul 17, 2010 at 06:24:55PM +0300, Alex Kozlov wrote:
> > After updating my buildbox from 26 April 8-STABLE
> > to 8.1-RC2 I constantly getting SIGEPIPE
> 
> > portsnap:
> > Fetching 4 metadata patches... done.
> > Applying metadata patches... done.
> > Fetching 0 metadata files... done.
> > Fetching 27 patches.....10....20... done.
> > Applying patches... done.
> > Fetching 3 new ports or files... done.
> > sort: write failed: standard output: Broken pipe
> > sort: write error
> > Removing old files and directories... done.
> 
> > sudo make -C /usr/ports/converters/ascii2binary:
> > ===>  Patching for ascii2binary-2.13_2
> > ===>  Applying FreeBSD patches for ascii2binary-2.13_2
> > ===>   ascii2binary-2.13_2 depends on shared library: intlgrep: writing output: Broken pipe
> > grep: writing output: Broken pipe
> [snip repetition]
> >  - found
> >  ===>  Configuring for ascii2binary-2.13_2
> 
> > Does anyone know something about this issue?
> 
> This looks more like the absence of SIGPIPE than an inappropriate
> SIGPIPE. I can reproduce both of those error messages by running the
> commands with SIGPIPE ignored. grep(1) seems to behave strangely on
> write errors, not aborting, for example
>   yes | { trap '' PIPE; grep -v foo; echo $? >&2; } | :
> prints an endless stream of error messages.
> 
> Note that sh(1) silently ignores attempts to change the disposition of
> signals that were ignored on entry to the shell, so a
>   trap - PIPE
> is unlikely to help you.
> 
> Similarly, SIGPIPE may be blocked (masked). Few programs expect this.
> 
> The -i and -j options in procstat should be helpful in finding what
> exactly is wrong with SIGPIPE. (These options are relatively new, but
> should be in 8.1.)

Might be, but now I have a feel that something more strange happens
there. One of my workstations does not exhibit the behaviour, while
another one did.

I composed the following grep wrapper to catch the situation you
guessed:

#!/bin/sh
disp=$(procstat -i $$ | awk '/PIPE/{print $4}')
if expr -- $disp : I >/dev/null ; then
	echo "grep: SIGPIPE ignored" >/dev/tty
	kill -STOP $$
fi
exec /usr/bin/grep "$@"

Amazingly enough, the messages stopped spitting. Even more, I cannot
reproduce them on the machine without the wrapper.

Side note: despite ports/Mk/bsd.commands.mk defining GREP and EGREP,
there are still several instances of the direct grep invocation
among Mk/* files. Do port people consider this worth fixing ?
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