Parent shell gets stopped when a child shell is created with job control but not interactive (bash -mc)

[Eduardo A . Bustamante López]

This works fine:

address@hidden:~$ ~/local/bin/bash -s <<< 'for i in . .; do (~/local/bin/bash 
-mic ": & wait") ; done'
[1] 1629
[1]+  Done                    :
[1] 1631
[1]+  Done                    :

-----
This does not:

address@hidden:~$ ~/local/bin/bash -s <<< 'for i in . .; do (~/local/bin/bash 
-mc ": & wait") ; done'
[1]+  Done                    :

[1]+  Stopped                 ~/local/bin/bash -s <<< 'for i in . .; do 
(~/local/bin/bash -mc ": & wait") ; done'


-----
Here's my OS and bash information (bash is
2e4d3851f76a94dfc21af046e0dfd84b954b0f50, from devel)

address@hidden:~$ cat /etc/debian_version 
7.3
address@hidden:~$ uname -a
Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux
address@hidden:~$ ~/local/bin/bash --version
GNU bash, version 4.3.0(1)-release (x86_64-unknown-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.


-----
Here's a sample output from strace when running this (I removed lots
of lines, didn't want to flood the list):


strace -fo bash-mc.log ~/local/bin/bash -s <<< 'for i in . .; do 
(~/local/bin/bash -mc ": & wait") ; done'

29747 execve("/home/dualbus/local/bin/bash", ["/home/dualbus/local/bin/bash", 
"-s"], [/* 24 vars */]) = 0
29747 brk(0)                            = 0x149c000
29747 rt_sigprocmask(SIG_BLOCK, [INT CHLD], [], 8) = 0
[...] 1st child
29747 clone(child_stack=0, 
flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 
child_tidptr=0x7f58bff209d0) = 29748
29747 rt_sigprocmask(SIG_SETMASK, [],  <unfinished ...>
29748 rt_sigprocmask(SIG_SETMASK, [],  <unfinished ...>
29747 <... rt_sigprocmask resumed> NULL, 8) = 0
29747 rt_sigprocmask(SIG_BLOCK, [CHLD],  <unfinished ...>
29748 <... rt_sigprocmask resumed> NULL, 8) = 0
29748 rt_sigaction(SIGTSTP, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0},  
<unfinished ...>
29747 <... rt_sigprocmask resumed> [], 8) = 0
29748 <... rt_sigaction resumed> {SIG_DFL, [], 0}, 8) = 0
29747 rt_sigprocmask(SIG_SETMASK, [],  <unfinished ...>
29748 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0},  
<unfinished ...>
29747 <... rt_sigprocmask resumed> NULL, 8) = 0
29747 rt_sigprocmask(SIG_BLOCK, [CHLD],  <unfinished ...>
[...] lots of stuff
29748 open("/home/dualbus/local/share/locale/en_US/LC_MESSAGES/bash.mo", 
O_RDONLY) = -1 ENOENT (No such file or directory)
29748 open("/home/dualbus/local/share/locale/en/LC_MESSAGES/bash.mo", O_RDONLY) 
= -1 ENOENT (No such file or directory)
29748 write(2, "[1]+  Done                    :\n", 32) = 32
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [CHLD], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [CHLD], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [CHLD], NULL, 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29748 --- SIGCHLD (Child exited) @ 0 (0) ---
29748 wait4(-1, 0x7fff8fdcad80, WNOHANG|WSTOPPED|WCONTINUED, NULL) = -1 ECHILD 
(No child processes)
29748 rt_sigreturn(0xffffffffffffffff)  = 0
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29748 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29748 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29748 setpgid(0, 29746)                 = 0
29748 exit_group(0)                     = ?
29747 <... wait4 resumed> [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 
29748
29747 rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{0x460380, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29747 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29747 --- SIGCHLD (Child exited) @ 0 (0) ---
29747 wait4(-1, 0x7ffff870cd80, WNOHANG, NULL) = -1 ECHILD (No child processes)
29747 rt_sigreturn(0xffffffffffffffff)  = 0
29747 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29747 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29747 rt_sigprocmask(SIG_BLOCK, [INT CHLD], [], 8) = 0
29747 clone(child_stack=0, 
flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, 
child_tidptr=0x7f58bff209d0) = 29750
29747 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29747 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29747 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29747 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29747 rt_sigaction(SIGINT, {0x460380, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29747 wait4(-1,  <unfinished ...>
29750 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29750 rt_sigaction(SIGTSTP, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], 0}, 8) = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], 0}, 8) = 0
29750 rt_sigaction(SIGTTOU, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], 0}, 8) = 0
29750 rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGQUIT, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_IGN, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGCHLD, {SIG_DFL, [], SA_RESTORER|SA_RESTART, 
0x7f58bf5914f0}, {0x4628b0, [], SA_RESTORER|SA_RESTART, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGCHLD, {0x4628b0, [], SA_RESTORER|SA_RESTART, 
0x7f58bf5914f0}, {SIG_DFL, [], SA_RESTORER|SA_RESTART, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGINT, {0x4862b0, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
29750 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29750 rt_sigprocmask(SIG_BLOCK, ~[RTMIN RT_1], [], 8) = 0
29750 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
29750 rt_sigaction(SIGINT, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{0x4862b0, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGQUIT, {SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f58bf5914f0}, 8) = 0
29750 rt_sigaction(SIGCHLD, {SIG_DFL, [], SA_RESTORER|SA_RESTART, 
0x7f58bf5914f0}, {0x4628b0, [], SA_RESTORER|SA_RESTART, 0x7f58bf5914f0}, 8) = 0
29750 execve("/home/dualbus/local/bin/bash", ["/home/dualbus/local/bin/bash", 
"-mc", ": & wait"], [/* 24 vars */]) = 0
29750 brk(0)                            = 0x9a8000
[...] before the loop
29750 stat(".", {st_mode=S_IFDIR|0770, st_size=4096, ...}) = 0
29750 getpid()                          = 29750
29750 open("/usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache", O_RDONLY) = 3
29750 fstat(3, {st_mode=S_IFREG|0644, st_size=26066, ...}) = 0
29750 mmap(NULL, 26066, PROT_READ, MAP_SHARED, 3, 0) = 0x7f276537f000
29750 close(3)                          = 0
29750 getppid()                         = 29747
29750 brk(0x9af000)                     = 0x9af000
29750 brk(0x9b0000)                     = 0x9b0000
29750 brk(0x9b1000)                     = 0x9b1000
29750 getpgrp()                         = 29746
29750 dup(2)                            = 3
29750 getrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=4*1024}) = 0
29750 fcntl(255, F_GETFD)               = -1 EBADF (Bad file descriptor)
29750 dup2(3, 255)                      = 255
29750 close(3)                          = 0
29750 ioctl(255, TIOCGPGRP, [29748])    = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 
{0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 kill(0, SIGTTIN)                  = 0
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 rt_sigaction(SIGTTIN, {0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 ioctl(255, TIOCGPGRP, [29748])    = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 
{0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 kill(0, SIGTTIN)                  = 0
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 rt_sigaction(SIGTTIN, {0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 ioctl(255, TIOCGPGRP, [29748])    = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 
{0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 kill(0, SIGTTIN)                  = 0
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 rt_sigaction(SIGTTIN, {0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 ioctl(255, TIOCGPGRP, [29748])    = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 
{0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 kill(0, SIGTTIN)                  = 0
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 --- SIGTTIN (Stopped (tty input)) @ 0 (0) ---
29750 rt_sigaction(SIGTTIN, {0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 
{SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
29750 ioctl(255, TIOCGPGRP, [29748])    = 0
29750 rt_sigaction(SIGTTIN, {SIG_DFL, [], SA_RESTORER, 0x7f27649e34f0}, 
{0x462a10, [], SA_RESTORER, 0x7f27649e34f0}, 8) = 0
[...] goes on forever


I can provide the full log in case it's needed. Beware that this bug
seems to hang strace (had to kill -9 it) and when run under gdb while
set follow-fork-mode child, gdb seemed to die, and then two shells
were running at the same time.


By the way, are compressed log file attachments OK in this list?

-- 
Eduardo Alan Bustamante López