gri3-wm/testcases/lib/SocketActivation.pm

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package SocketActivation;
# vim:ts=4:sw=4:expandtab
use IO::Socket::UNIX; # core
use Cwd qw(abs_path); # core
use POSIX; # core
use AnyEvent::Handle; # not core
use Exporter 'import';
use v5.10;
our @EXPORT = qw(activate_i3);
#
# Starts i3 using socket activation. Creates a listening socket (with bind +
# listen) which is then passed to i3, who in turn calls accept and handles the
# requests.
#
# Since the kernel buffers the connect, the parent process can connect to the
# socket immediately after forking. It then sends a request and waits until it
# gets an answer. Obviously, i3 has to be initialized to actually answer the
# request.
#
# This way, we can wait *precisely* the amount of time which i3 waits to get
# ready, which is a *HUGE* speed gain (and a lot more robust) in comparison to
# using sleep() with a fixed amount of time.
#
# unix_socket_path: Location of the socket to use for the activation
# display: X11 $ENV{DISPLAY}
# configfile: path to the configuration file to use
# logpath: path to the logfile to which i3 will append
# cv: an AnyEvent->condvar which will be triggered once i3 is ready
#
sub activate_i3 {
my %args = @_;
# remove the old unix socket
unlink($args{unix_socket_path});
# pass all file descriptors up to three to the children.
# we need to set this flag before opening the socket.
open(my $fdtest, '<', '/dev/null');
$^F = fileno($fdtest);
close($fdtest);
my $socket = IO::Socket::UNIX->new(
Listen => 1,
Local => $args{unix_socket_path},
);
my $pid = fork;
if (!defined($pid)) {
die "could not fork()";
}
if ($pid == 0) {
$ENV{LISTEN_PID} = $$;
$ENV{LISTEN_FDS} = 1;
$ENV{DISPLAY} = $args{display};
$ENV{PATH} = join(':',
'../i3-nagbar',
'../i3-msg',
'../i3-config-wizard',
'../i3bar',
'..',
$ENV{PATH}
);
# Only pass file descriptors 0 (stdin), 1 (stdout), 2 (stderr) and
# 3 (socket) to the child.
$^F = 3;
# If the socket does not use file descriptor 3 by chance already, we
# close fd 3 and dup2() the socket to 3.
if (fileno($socket) != 3) {
POSIX::close(3);
POSIX::dup2(fileno($socket), 3);
}
# Construct the command to launch i3. Use maximum debug level, disable
# the interactive signalhandler to make it crash immediately instead.
my $i3cmd = abs_path("../i3") . " -V -d all --disable-signalhandler";
# Append to $args{logpath} instead of overwriting because i3 might be
# run multiple times in one testcase.
my $cmd = "exec $i3cmd -c $args{configfile} >>$args{logpath} 2>&1";
# We need to use the shell due to using output redirections.
exec "/bin/sh", '-c', $cmd;
# if we are still here, i3 could not be found or exec failed. bail out.
exit 1;
}
# close the socket, the child process should be the only one which keeps a file
# descriptor on the listening socket.
$socket->close;
# We now connect (will succeed immediately) and send a request afterwards.
# As soon as the reply is there, i3 is considered ready.
my $cl = IO::Socket::UNIX->new(Peer => $args{unix_socket_path});
my $hdl;
$hdl = AnyEvent::Handle->new(
fh => $cl,
on_error => sub {
$hdl->destroy;
$args{cv}->send(0);
});
# send a get_tree message without payload
$hdl->push_write('i3-ipc' . pack("LL", 0, 4));
# wait for the reply
$hdl->push_read(chunk => 1, => sub {
my ($h, $line) = @_;
$args{cv}->send(1);
undef $hdl;
});
return $pid;
}
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