eval: Do not cache value of eflag in evaltree

eval: Do not cache value of eflag in evaltree

Patrick Brünn <P.Bruenn@beckhoff.com> wrote:
>
> Since we are migrating to Debian bullseye, we discovered a new behavior
> with our scripts, which look like this:
>>#!/bin/sh
>>cleanup() {
>>        set +e^M
>>        rmdir ""
>>}
>>set -eu
>>trap 'cleanup' EXIT INT TERM
>>echo 'Hello world!'
>
> With old dash v0.5.10.2 this script would return 0 as we expected it.
> But since commit 62cf6955f8abe875752d7163f6f3adbc7e49ebae it returns
> the last exit code of our cleanup function.
> Reverting that commit gives a merge conflict, but it seems to fix _our_
> problem. As that topic appears too complex to us I want to ask the
> experts here:
>
> Is this change in behavior intended, by dash?
>
> Our workaround at the moment would be:
>>trap 'cleanup || true' EXIT INT TERM

Thanks for the report.  This is actually a fairly old bug with
set -e that's just been exposed by the exit status change.  What's
really happening is that cleanup itself is triggering a set -e
exit incorrectly because evaltree cached the value of eflag prior
to the function call.

This patch should fix the problem.

Reported-by: Patrick Brünn <P.Bruenn@beckhoff.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Patrick Brünn <P.Bruenn@beckhoff.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>