external command causes SIGINT to be ignored within non-forking subshell about ksh HOT 6 CLOSED

It appears that the root cause is probably the fact that ksh only properly disables job control in non-forked/virtual subshells if they are command substitutions. I'm testing a fix for #89 and that fix makes this bug go away as well.

from ksh.

This diff fixes it for me. For some reason I can't fathom, sh_fork() did not reset shp->savesig when in a virtual subshell, causing SIGINT to be ignored after running an external command using sh_fork() for the duration of the virtual subshell. The patch does not cause any regression test failures for me, on a ksh compiled with and without -DSHOPT_SPAWN=0.

diff --git a/src/cmd/ksh93/sh/xec.c b/src/cmd/ksh93/sh/xec.c
index a6ad507..baa8d6d 100644
--- a/src/cmd/ksh93/sh/xec.c
+++ b/src/cmd/ksh93/sh/xec.c
@@ -2951,13 +2951,10 @@ pid_t sh_fork(Shell_t *shp,int flags, int *jobid)
 	shp->savesig = -1;
 	while(_sh_fork(shp,parent=fork(),flags,jobid) < 0);
 	sh_stats(STAT_FORKS);
-	if(!shp->subshell)
-	{
-		sig = shp->savesig;
-		shp->savesig = 0;
-		if(sig>0)
-			kill(getpid(),sig);
-	}
+	sig = shp->savesig;
+	shp->savesig = 0;
+	if(sig>0)
+		kill(getpid(),sig);
 	job_fork(parent);
 	return(parent);
 }

from ksh.

This bug is not present in ksh2020, which has removed spawnveg.

from ksh.

This probably doesn't need to be a blocking bug now that #79 is fixed.

from ksh.

Actually, after the fix for #79, now this bug still occurs when compiled with SHOPT_SPAWN on, and if the shell is interactive and has job control on:

$ arch/*/bin/ksh -i -c '(/usr/bin/true; while :; do :; done); exit'
^C^C^C^C^C

from ksh.

It appears that the root cause is probably the fact that ksh only properly disables job control in non-forked/virtual subshells if they are command substitutions. I'm testing a fix for #89 and that fix makes this bug go away as well.

Of course it does; the #89 fix makes ksh use sh_ntfork() instead of sh_fork(), where the bug is. So that was a false lead.

from ksh.