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job_init(): fix init on setpgid() permission denied (re: 41ebb55a)

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Symptoms of this bug below. These only seem to occur on Linux and
only if you replace your initial login shell by ksh using 'exec'.

1. An erroneous 'Interrupt' message is printed after stopping the
   read builtin in a script. Reproducer:

	$ exec arch/*/bin/ksh
	$ cat ./reproducer.sh
	#!/bin/sh
	read foo
	$ ./reproducer.sh
	^C$ <Enter>
	[1] + Interrupt                ../reproducer.sh

2. Ctrl+C fails to stop /bin/package make. Reproducer:

	$ exec arch/*/bin/ksh
	$ mv arch arch.old
	$ bin/package make
	# Press Ctrl+C multiple times

Analysis: In 41ebb55a, I made an error in changing job_init() to
work correctly on non-interactive shells. This line from before:

552|	if(possible = (setpgid(0,job.mypgid)>=0) || errno==EPERM)

was changed to:

555|	possible = (setpgid(0,job.mypgid) >= 0);
556|	if(sh_isoption(SH_INTERACTIVE) && (possible || errno==EPERM))

That is wrong. Before, 'possible' was set to 1 (true) if setpgid()
either succeeded or failed with EPERM. After, it is only set to 1
if setpgid() succeeds. As a result, job control initialisation is
aborted later on upon a test for non-zero 'possible'.

src/cmd/ksh93/sh/jobs.c: job_init():
- Once again set possible to 1 even if setpgid() fails with EPERM.

Thanks to @JohnoKing for the bug report and reproducers.

Resolves: https://github.com/ksh93/ksh/issues/210
This commit is contained in:
Martijn Dekker 2021-03-07 17:01:17 +00:00
parent aad74597f7
commit 40860dac20
2 changed files with 5 additions and 2 deletions
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3
NEWS
View file

@ -13,6 +13,9 @@ Any uppercase BUG_* names are modernish shell bug IDs.
if they match a normal (non-**) glob pattern. For example, if '/lnk' is a
symlink to a directory, '/lnk/**' and '/l?k/**' now work as you would expect.
- Fixed a bug introduced on 2021-02-11 that caused job control on interactive
ksh sessions to misbehave if the login shell was replaced by ksh using 'exec'.
2021-03-06:
- Fixed an old expansion bug: expansions of type ${var=value} and ${var:=value}

4
src/cmd/ksh93/sh/jobs.c
View file

@ -552,8 +552,8 @@ void job_init(Shell_t *shp, int lflag)
job.mypgid = shp->gd->pid;
}
#ifdef SIGTSTP
possible = (setpgid(0,job.mypgid) >= 0);
if(sh_isoption(SH_INTERACTIVE) && (possible || errno==EPERM))
possible = (setpgid(0,job.mypgid) >= 0) || errno==EPERM;
if(sh_isoption(SH_INTERACTIVE) && possible)
{
/* wait until we are in the foreground */
while((job.mytgid=tcgetpgrp(JOBTTY)) != job.mypgid)