Regression: `stty -echo` in scripts no longer works

[vmihalko]

Description:

In ksh versions later than v1.0.0-beta.1, setting stty -echo in a script no longer works as expected. This issue did not occur in earlier versions.

Bisected Commit:

I performed a git bisect between the last known good tag (reboot) and the first known bad tag (v1.0.0-beta.1). The regression was introduced in commit 41ebb55a3a9133f58cf3cc1c47e83bb5dc11404e.

Reproducer:

Create a script e.g. repro.ksh with the following contents:

#!/bin/ksh
read a
stty -echo
read b

Run the script:

ksh repro.ksh

Expected Behavior:

• Input for a should be visible.
• Input for b should not be echoed to the terminal.

Actual Behavior:

• Input for a is visible as expected.
• Input for b is also visible, despite stty -echo being set.

[McDutchie]

Thanks for the report. I can reproduce the bug on macOS.

[McDutchie]

Also reproduced on Linux and FreeBSD.

I can not reproduce this problem on Solaris 11.4 with its external stty command, which is interesting.

I also cannot reproduce it on any system if the optional stty built-in is used. To test that, invoke the following after bin/package use using ksh issue836_builtin.sh (requires a system on which we build dynamic libraries):

# issue836_builtin.sh
builtin -f shell stty || exit
read a
stty -echo
read b

[McDutchie]

I found the cause of the problem by systematic elimination of the changes introduced in the commit that you identified.

The problem was that the tty_set(-1, 0, NULL) call here, which invalidates stored terminal attributes, was no longer being executed when running a script (note that job.jobcontrol is 0/false for scripts).

ksh/src/cmd/ksh93/sh/jobs.c

Lines 1423 to 1432 in ce3648d

	else if(job.jobcontrol)
	{
	if(pw->p_pid == tcgetpgrp(JOBTTY))
	{
	if(pw->p_pgrp==0)
	pw->p_pgrp = pw->p_pid;
	job_reset(pw);
	}
	tty_set(-1, 0, NULL);
	}

The following patch fixes the problem for me. Please test:

diff --git a/src/cmd/ksh93/sh/jobs.c b/src/cmd/ksh93/sh/jobs.c
index c65bc6e66..513afb558 100644
--- a/src/cmd/ksh93/sh/jobs.c
+++ b/src/cmd/ksh93/sh/jobs.c
@@ -1420,9 +1420,9 @@ int	job_wait(pid_t pid)
 			kill(sh.current_pid,SIGTSTP);
 		}
 	}
-	else if(job.jobcontrol)
+	else
 	{
-		if(pw->p_pid == tcgetpgrp(JOBTTY))
+		if(job.jobcontrol && pw->p_pid == tcgetpgrp(JOBTTY))
 		{
 			if(pw->p_pgrp==0)
 				pw->p_pgrp = pw->p_pid;

[McDutchie]

Fix confirmed on macOS, Linux and FreeBSD, so I'll commit it.