eval: Do not cache value of eflag in evaltree

[Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>]

Patrick Brünn <P.Bruenn@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

diff --git a/src/eval.c b/src/eval.c
index 9476fbb..3337f71 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -252,18 +252,10 @@ evaltree(union node *n, int flags)
 			popredir(0);
 		goto setstatus;
 	case NCMD:
-#ifdef notyet
-		if (eflag && !(flags & EV_TESTED))
-			checkexit = ~0;
-		status = evalcommand(n, flags, (struct backcmd *)NULL);
-		goto setstatus;
-#else
 		evalfn = evalcommand;
 checkexit:
-		if (eflag && !(flags & EV_TESTED))
-			checkexit = ~0;
+		checkexit = ~flags & EV_TESTED;
 		goto calleval;
-#endif
 	case NFOR:
 		evalfn = evalfor;
 		goto calleval;
@@ -323,7 +315,7 @@ setstatus:
 out:
 	dotrap();
 
-	if (checkexit & status)
+	if (eflag && checkexit && status)
 		goto exexit;
 
 	if (flags & EV_EXIT) {
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt