Re: [PATCH] test: Remove race between commands run in the same context

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Apr 05, 2023 at 02:23:24PM +0200, Stefano Brivio wrote:
> On Wed,  5 Apr 2023 11:56:42 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > context_run() has a race condition if two commands are run in close
> > proximity (generally involving at least one in the background).  Because we
> > always use the same name for the temporary fifo files, if another command
> > is issued while the fifos for the first still exist, mkfifo will fail,
> > typically causing the entire test script to jam.
> > 
> > Create unique names for the temporary fifos to avoid this problem.
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  test/lib/context | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/test/lib/context b/test/lib/context
> > index d9d8260..09cad89 100644
> > --- a/test/lib/context
> > +++ b/test/lib/context
> > @@ -93,8 +93,8 @@ context_run() {
> >  	__name="$1"
> >  	__log="${LOGDIR}/context_${__name}.log"
> >  	__enter="${STATESETUP}/context_${__name}.enter"
> > -	__stdout="${STATESETUP}/context_${__name}.stdout"
> > -	__stderr="${STATESETUP}/context_${__name}.stderr"
> > +	__stdout="$(mktemp -u "${STATESETUP}/context_${__name}.stdout.XXXXXXXX")"
> > +	__stderr="$(mktemp -u "${STATESETUP}/context_${__name}.stderr.XXXXXXXX")"
> 
> In practice, this is never going to be an issue, but strictly
> speaking, -u doesn't guarantee the name is unique.

Yeah, I know.

> On the other hand we don't need a loop (or further directories) with
> this, so the simplicity of it might be preferable over correctness...

Right, that's the conclusion I came to as well.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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