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Description of problem:
FYI I work for IBM and we have been shipping a fixed version of pdksh
with one of our products. One of our customers wanted to get this fix
over to the guys at SuSE so we provided it to them. I wanted to
provide it to you guys(as well as Debian) so that we could get it
fixed in the major distributions as it appears it is no longer being
maintained.

---------------------------------------------------------------------
The gist of the problem was that the shell was waiting for tty input
in a non-interactive script. The result was that the shell would hang
waiting for input that was never coming. I remember writing an example
that ran fine on other ksh's, but failed on pdksh. Sent the example to
the maintainer of pdksh and he suggested the fix that I put in. If I
remember right, it was basically adding a check for if it was an
interactive shell or not. This got us past the problem and was
supposed to end up in the official pdksh. That was a number of years
ago and still no sign of the fix : (
---------------------------------------------------------------------
--- jobs.c      2001-10-27 15:31:57.000000000 -0400
+++ /home/possum/pdksh-5.2.14/jobs.c    1999-07-13 12:50:56.000000000
-0400
@@ -334,17 +334,12 @@
        int i;

        if (Flag(FMONITOR)) {
-               int use_tty;
-               if (Flag(FTALKING)) {
-                       /* Don't call get_tty() 'til we own the tty
process     group */
-                       use_tty = 1;
-                       tty_init(FALSE);
-               } else
-                       use_tty = 0;
+               /* Don't call get_tty() 'til we own the tty process
group */
+               tty_init(FALSE);

 # ifdef TTY_PGRP
                /* no controlling tty, no SIGT* */
-               ttypgrp_ok = use_tty && tty_fd >= 0 && tty_devtty;
+               ttypgrp_ok = tty_fd >= 0 && tty_devtty;

                if (ttypgrp_ok && (our_pgrp = getpgID()) < 0) {
                        warningf(FALSE, "j_init: getpgrp() failed: %s",
@@ -400,10 +395,8 @@
                                        strerror(errno));
                }
 #  endif /* NTTYDISC && TIOCSETD */
-               if (Flag(FTALKING)) {
-                       if (!ttypgrp_ok)
-                               warningf(FALSE, "warning: won't have
full job   control");
-               }
+               if (!ttypgrp_ok)
+                       warningf(FALSE, "warning: won't have full job
control");
 # endif /* TTY_PGRP */
                if (tty_fd >= 0)
                        get_tty(tty_fd, &tty_state);



Version-Release number of selected component (if applicable):
any pdksh

How reproducible:
Always

Steps to Reproduce:
Here is the reproducable error:

two scripts:

::::::::::::::
test1.ksh
::::::::::::::
#!/bin/ksh

./test2.ksh&


::::::::::::::
test2.ksh
::::::::::::::
#!/bin/ksh

set -m
xclock &

exit 1

chmod both scripts +x
NOTE: Make sure you have your DISPLAY variable properly set.
Run: ./test1.ksh &

Actual Results:  You should get a "Stopped" message(you may have to
hit enter to see it), the xclock command should  not run and both
scripts should be left running(you will need to kill them).

A couple of things to note at this point:
1) if you kill test1.ksh, test2.ksh will immediately start hogging the cpu
2) test2.ksh will become parented by init(1) (it was originally
parented by pidof(test1.ksh))

Once you kill test2.ksh everything should return to normal.


Expected Results:  On a normally(properly) working ksh, the scripts
should both finish and only the xclock should be left running. This is
the response I got from Solaris, AIX and the fixed pdksh that we ship.

Additional info:

Please feel free to contact me for any additional information
pstroud


Here is the patch we put into place:

--- jobs.c      2001-10-27 15:31:57.000000000 -0400
+++ /home/possum/pdksh-5.2.14/jobs.c    1999-07-13 12:50:56.000000000
-0400
@@ -334,17 +334,12 @@
        int i;

        if (Flag(FMONITOR)) {
-               int use_tty;
-               if (Flag(FTALKING)) {
-                       /* Don't call get_tty() 'til we own the tty
process     group */
-                       use_tty = 1;
-                       tty_init(FALSE);
-               } else
-                       use_tty = 0;
+               /* Don't call get_tty() 'til we own the tty process
group */
+               tty_init(FALSE);

 # ifdef TTY_PGRP
                /* no controlling tty, no SIGT* */
-               ttypgrp_ok = use_tty && tty_fd >= 0 && tty_devtty;
+               ttypgrp_ok = tty_fd >= 0 && tty_devtty;

                if (ttypgrp_ok && (our_pgrp = getpgID()) < 0) {
                        warningf(FALSE, "j_init: getpgrp() failed: %s",
@@ -400,10 +395,8 @@
                                        strerror(errno));
                }
 #  endif /* NTTYDISC && TIOCSETD */
-               if (Flag(FTALKING)) {
-                       if (!ttypgrp_ok)
-                               warningf(FALSE, "warning: won't have
full job   control");
-               }
+               if (!ttypgrp_ok)
+                       warningf(FALSE, "warning: won't have full job
control");
 # endif /* TTY_PGRP */
                if (tty_fd >= 0)
                        get_tty(tty_fd, &tty_state);