From 4350174a5d4acabf78f97b28c6d0ae68ec703e78 Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Sun, 30 Mar 2025 00:14:35 +0000
Subject: [PATCH] Fix 'stty -echo' in scripts (re: 41ebb55a)
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Vincent Mihalkovič (@vmihalko) reports:
> 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.
>
> 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 41ebb55a.
>
> Reproducer:
>   read a
>   stty -echo
>   read b
>
> 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.

Analysis:

The problem was that the tty_set(-1, 0, NULL) call below, which
invalidates saved terminal attributes, was no longer being executed
when running a script (note that job.jobcontrol is 0/false for
scripts). See edit.c for the tty_set function and what it does.

src/cmd/ksh93/sh/jobs.c
1423:	else if(job.jobcontrol)
1424:	{
1425:		if(pw->p_pid == tcgetpgrp(JOBTTY))
1426:		{
...skipped for brevity...
1430:		}
1431:		tty_set(-1, 0, NULL);
1432:	}

So, after running an external command such as stty, terminal
attributes that should have been invalidated were restored upon the
next 'read'. This was undoing the effect of the stty command.

src/cmd/ksh93/sh/jobs.c: job_wait():
- Move the test for job.jobcontrol so that saved terminal
  attributes are again invalidated after running an external
  command when job control for interactive shells is not active.

Resolves: https://github.com/ksh93/ksh/issues/836
---
 src/cmd/ksh93/sh/jobs.c         | 4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/cmd/ksh93/sh/jobs.c b/src/cmd/ksh93/sh/jobs.c
index c65bc6e66094..513afb5582ab 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;