ash: eval: Add vfork support

Upstream commit:

    Date: Sat, 19 May 2018 02:39:56 +0800
    eval: Add vfork support

    This patch adds basic vfork support for the case of a simple command.

Upstream commit:

    Date: Tue, 12 Jan 2021 17:11:19 +1100
    jobs: Always reset SIGINT/SIGQUIT handlers

    On Fri, Jan 08, 2021 at 08:55:41PM +0000, Harald van Dijk wrote:
    > On 18/05/2018 19:39, Herbert Xu wrote:
    > > This patch adds basic vfork support for the case of a simple command.
    > > ...  @@ -879,17 +892,30 @@ forkchild(struct job *jp, union node *n, int
    > > mode)
    > >   		}
    > >   	}
    > >   	if (!oldlvl && iflag) {
    > > -		setsignal(SIGINT);
    > > -		setsignal(SIGQUIT);
    > > +		if (mode != FORK_BG) {
    > > +			setsignal(SIGINT);
    > > +			setsignal(SIGQUIT);
    > > +		}
    > >   		setsignal(SIGTERM);
    > >   	}
    > > +
    > > +	if (lvforked)
    > > +		return;
    > > +
    > >   	for (jp = curjob; jp; jp = jp->prev_job)
    > >   		freejob(jp);
    > >   }
    >
    > This leaves SIGQUIT ignored in background jobs in interactive shells.
    >
    >   ENV= dash -ic 'dash -c "kill -QUIT \$\$; echo huh" & wait'
    >
    > As of dash 0.5.11, this prints "huh". Before, the subprocess process killed
    > itself before it could print anything. Other shells do not leave SIGQUIT
    > ignored.
    >
    > (In a few other shells, this also prints "huh", but in those other shells,
    > that is because the inner shell chooses to ignore SIGQUIT, not because the
    > outer shell leaves it ignored.)

    Thanks for catching this.  I have no idea how that got in there
    and it makes no sense whatsoever.  This patch removes the if
    conditional.

    Fixes: e94a964e7dd0 ("eval: Add vfork support")

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index fba898943..4b3319824 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -643,6 +643,8 @@ int sigaction_set(int sig, const struct sigaction *act) FAST_FUNC;
 int sigprocmask_allsigs(int how) FAST_FUNC;
 /* Return old set in the same set: */
 int sigprocmask2(int how, sigset_t *set) FAST_FUNC;
+/* SIG_BLOCK all signals, return old set: */
+int sigblockall(sigset_t *set) FAST_FUNC;
 /* Standard handler which just records signo */
 extern smallint bb_got_signal;
 void record_signo(int signo); /* not FAST_FUNC! */