Ting-Wei Lan authored Aug 19, 2018 and Philip Withnall committed Aug 20, 2018

In file gio/gtestdbus.c, function watch_parent, there is a loop which
waits for commands sent from the parent process and kills all processes
recorded in 'pids_to_kill' array on parent process exit. The detection
of parent process exit is done by calling g_poll and checking whether
the returned event is G_IO_HUP. However, 'revents' is a bit mask, and
we should use a bitwise-AND check instead of the equality check here.

It seems to work fine on Linux, but it fails on FreeBSD because the
g_poll returns both G_IO_IN and G_IO_HUP on pipe close. This means the
watcher process continues waiting for commands after the parent process
exit, and g_io_channel_read_line returns G_IO_STATUS_EOF with 'command'
set to NULL. Then the watcher process crashes with segfault when calling
sscanf because 'command' is NULL. Since the test result is already
reported by the parent process as 'OK', this kind of crash is likely to
be unnoticed unless someone checks dmesg messages after the t...