Re: [PATCH] generic/397: be compatible with ignored SIGPIPE

[Eryu Guan <eguan@redhat.com>]

On Mon, Jun 12, 2017 at 02:15:28PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> If generic/397 is executed in an environment with SIGPIPE ignored, it
> fails because the 'yes' program prints an error message:
> 
>     yes: standard output: Broken pipe
>     yes: write error
> 
> This can be reproduced with:
> 
>     trap '' SIGPIPE; ./check generic/397
> 
> Fix it by generating the string of 255 y's using just 'head' and 'tr'
> instead of 'yes', 'head', and 'tr'.
> 
> Although it's not really a good idea to execute xfstests with SIGPIPE
> ignored, this is the only test I've noticed where it causes a problem,
> so it might as well be fixed in the test.

I'm just curious, why do you need to run fstests with SIGPIPE ignored?

> 
> It would be much nicer to prevent this problem for all tests by making
> the 'check' script restore the default SIGPIPE handler.  But that isn't
> straightforward because bash's 'trap' builtin doesn't allow un-ignoring
> signals that were ignored on entry to the shell.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  tests/generic/397 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tests/generic/397 b/tests/generic/397
> index 7077d048..ba920891 100755
> --- a/tests/generic/397
> +++ b/tests/generic/397
> @@ -69,7 +69,7 @@ for dir in $SCRATCH_MNT/edir $SCRATCH_MNT/ref_dir; do
>  	touch $dir/empty > /dev/null
>  	$XFS_IO_PROG -t -f -c "pwrite 0 4k" $dir/a > /dev/null
>  	$XFS_IO_PROG -t -f -c "pwrite 0 33k" $dir/abcdefghijklmnopqrstuvwxyz > /dev/null
> -	maxname=$(yes | head -255 | tr -d '\n') # 255 character filename
> +	maxname=$(head -c 255 /dev/zero | tr '\0' y) # 255 character filename

Using perl seems simpler, we have some other tests do similar tasks
using perl too.

	maxname=$($PERL_PROG -e 'print "y" x 255;')

Thanks,
Eryu

>  	$XFS_IO_PROG -t -f -c "pwrite 0 1k" $dir/$maxname > /dev/null
>  	ln -s a $dir/symlink
>  	ln -s abcdefghijklmnopqrstuvwxyz $dir/symlink2
> -- 
> 2.13.1.508.gb3defc5cc-goog
> 
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