Background processes receive SIGINT even though they shouldn't

[Ingemar Nilsson]

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Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: linux-gnu
Compiler: i386-redhat-linux-gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i386'
- -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i386-redhat-linux-gnu'
- -DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
- -DSHELL -DHAVE_CONFIG_H  -I.  -I. -I./include -I./lib  -D_GNU_SOURCE
- -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -O2 -g -pipe
- -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -m32 -march=i386 -mtune=pentium4
- -fasynchronous-unwind-tables
uname output: Linux tyrannosaurus 2.6.14-1.1656_FC4 #1 Thu Jan 5
22:13:22 EST 2006 i686 i686 i386 GNU/Linux
Machine Type: i386-redhat-linux-gnu

Bash Version: 3.0
Patch Level: 16
Release Status: release

Description:
        In some cases, background processes receive SIGINT from the
        terminal where it was started even though the manual states
        that such processes are immune to keyboard-generated signals.
        This is best explained by trying out the example below.

        There is a reason for the seemingly complex sleep arrangement
        in test2. This is really a condensed version of a much larger
        script, but it still demonstrates the problem well.

Repeat-By:
        1) Create two shell scripts, test1 and test2, which are
supplied           below:

        test1:

        ### START SCRIPT ###
        #!/bin/bash

        test2 &

        while /bin/true; do
            echo test1 sleeping
            sleep 5
        done
        ### END SCRIPT ###

        test2:

        ### START SCRIPT ###
        #!/bin/bash

        while /bin/true; do
            echo test2 sleeping
            sleep 5 &
            SLEEP_PID=$!
            wait $SLEEP_PID
            unset SLEEP_PID
        done
        ### END SCRIPT ###

        2) Run test1 from the terminal
        3) Interrupt it with CTRL-C
        4) Notice that test2 was also interrupted. This can also be
           done by finding the PID of test2 and letting strace attach
           to the process before interrupting test1. Strace will report
           that a SIGINT was caught.

Fix:
        N/A

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