On Fri, Dec 2, 2016 at 6:28 AM, Vladimir Marek <vladimir.ma...@oracle.com>
wrote:
> Hi,
>
> I'm not sure what is going on, but the bash test suite was getting
> stopped (as if SIGSTOP was received) in the middle. Trying to find
> minimal set of conditions it came to this:
>
> - my ~/.bashrc has to contain 'cd /' (any dir works)
> - the tests have to first execute run-execscript, namely it has to
> execute exec6.sub, namely the line ${THIS_SH} -i ./exec8.sub
> - the file exec8.sub is reported as not found (I presume because of the
> 'cd /' in .bashrc)
> - the tests then have to run read-test, exactly in read2.sub when
> 'read -t 2 a < /dev/tty' was executed whole thing was stopped
>
> When I removed the 'cd' command from my ~/.bashrc, all worked fine.
>
> I then tried to make minimal reproducible case and came to this (this
> time there is no 'cd /' in my ~/.bashrc needed):
>
> $ bash -c 'bash -i i; bash -i i'
> bash -c 'bash -i i; bash -i i'
> bash: i: No such file or directory
>
> [1]+ Stopped bash -c 'bash -i i; bash -i i'
>
I can reproduce this with bash 4.4.5 on Debian 8.5.
foo@deb64:~$ bash -c 'bash -i 1; bash -i 2'
bash: 1: No such file or directory
[1]+ Stopped bash -c 'bash -i 1; bash -i 2'
foo@deb64:~$ echo $?
149
It was stopped by SIGTTIN. According to gdb backtrace it was killed by the
second "bash -i".
4099 while ((terminal_pgrp = tcgetpgrp (shell_tty)) != -1)
4100 {
4101 if (shell_pgrp != terminal_pgrp)
4102 {
4103 SigHandler *ottin;
4104
4105 ottin = set_signal_handler (SIGTTIN, SIG_DFL);
4106 kill (0, SIGTTIN);
4107 set_signal_handler (SIGTTIN, ottin);
4108 continue;
4109 }
4110 break;
4111 }
The problem is tcgetpgrp() still returns the pgrp of the first "bash -i"
when the second "bash -i" is running. This can be shown with following
example:
foo@deb64:~$ bash -c 'bash -i 1; sleep 9999'
bash: 1: No such file or directory <-- CTRL-C does not work here
root@deb64:~# ps t pts/10 j
PPID PID PGID SID TTY TPGID STAT UID TIME COMMAND
96886 96887 96887 96887 pts/10 97073 Ss 1001 0:00 -bash
96887 97072 97072 96887 pts/10 97073 S 1001 0:00 bash -c
bash -i 1; sleep 9999
97072 97074 97072 96887 pts/10 97073 S 1001 0:00 sleep 9999
Here the TPGID 97073 must be the first "bash -i" which has already exited.
Seems like for some reason the "bash -c" does not set the foreground pgrp
to the second "bash -i".
(Still learning the APUE book. Hope my analysis makes sense. :)
