1 package SocketActivation;
2 # vim:ts=4:sw=4:expandtab
6 use IO::Socket::UNIX; # core
7 use Cwd qw(abs_path); # core
8 use POSIX qw(:fcntl_h); # core
9 use AnyEvent::Handle; # not core
10 use AnyEvent::Util; # not core
11 use Exporter 'import';
14 our @EXPORT = qw(activate_i3);
17 # Starts i3 using socket activation. Creates a listening socket (with bind +
18 # listen) which is then passed to i3, who in turn calls accept and handles the
21 # Since the kernel buffers the connect, the parent process can connect to the
22 # socket immediately after forking. It then sends a request and waits until it
23 # gets an answer. Obviously, i3 has to be initialized to actually answer the
26 # This way, we can wait *precisely* the amount of time which i3 waits to get
27 # ready, which is a *HUGE* speed gain (and a lot more robust) in comparison to
28 # using sleep() with a fixed amount of time.
30 # unix_socket_path: Location of the socket to use for the activation
31 # display: X11 $ENV{DISPLAY}
32 # configfile: path to the configuration file to use
33 # logpath: path to the logfile to which i3 will append
34 # cv: an AnyEvent->condvar which will be triggered once i3 is ready
39 # remove the old unix socket
40 unlink($args{unix_socket_path});
42 my $socket = IO::Socket::UNIX->new(
44 Local => $args{unix_socket_path},
49 die "could not fork()";
52 $ENV{LISTEN_PID} = $$;
54 delete $ENV{DESKTOP_STARTUP_ID};
55 $ENV{DISPLAY} = $args{display};
56 $ENV{PATH} = join(':',
59 '../i3-config-wizard',
65 # We are about to exec, but we did not modify $^F to include $socket
66 # when creating the socket (because the file descriptor could have a
67 # number != 3 which would lead to i3 leaking a file descriptor). This
68 # caused Perl to set the FD_CLOEXEC flag, which would close $socket on
69 # exec(), effectively *NOT* passing $socket to the new process.
70 # Therefore, we explicitly clear FD_CLOEXEC (the only flag right now)
71 # by setting the flags to 0.
72 POSIX::fcntl($socket, F_SETFD, 0) or die "Could not clear fd flags: $!";
74 # If the socket does not use file descriptor 3 by chance already, we
75 # close fd 3 and dup2() the socket to 3.
76 if (fileno($socket) != 3) {
78 POSIX::dup2(fileno($socket), 3);
79 POSIX::close(fileno($socket));
82 # Make sure no file descriptors are open. Strangely, I got an open file
83 # descriptor pointing to AnyEvent/Impl/EV.pm when testing.
84 AnyEvent::Util::close_all_fds_except(0, 1, 2, 3);
86 # Construct the command to launch i3. Use maximum debug level, disable
87 # the interactive signalhandler to make it crash immediately instead.
88 my $i3cmd = abs_path("../i3") . " -V -d all --disable-signalhandler";
91 my $outdir = $args{outdir};
92 my $test = $args{testname};
94 if ($args{valgrind}) {
96 qq|valgrind -v --log-file="$outdir/valgrind-for-$test.log" | .
97 qq|--leak-check=full --track-origins=yes --num-callers=20 | .
98 qq|--tool=memcheck -- $i3cmd|;
101 my $logfile = "$outdir/i3-log-for-$test";
102 # Append to $logfile instead of overwriting because i3 might be
103 # run multiple times in one testcase.
104 my $cmd = "exec $i3cmd -c $args{configfile} >>$logfile 2>&1";
107 my $out = "$outdir/strace-for-$test.log";
109 # We overwrite LISTEN_PID with the correct process ID to make
110 # socket activation work (LISTEN_PID has to match getpid(),
111 # otherwise the LISTEN_FDS will be treated as a left-over).
112 $cmd = qq|strace -fF -s2048 -v -o "$out" -- | .
113 'sh -c "export LISTEN_PID=\$\$; ' . $cmd . '"';
116 # We need to use the shell due to using output redirections.
117 exec '/bin/sh', '-c', $cmd;
119 # if we are still here, i3 could not be found or exec failed. bail out.
123 # close the socket, the child process should be the only one which keeps a file
124 # descriptor on the listening socket.
127 # We now connect (will succeed immediately) and send a request afterwards.
128 # As soon as the reply is there, i3 is considered ready.
129 my $cl = IO::Socket::UNIX->new(Peer => $args{unix_socket_path});
131 $hdl = AnyEvent::Handle->new(
138 # send a get_tree message without payload
139 $hdl->push_write('i3-ipc' . pack("LL", 0, 4));
142 $hdl->push_read(chunk => 1, => sub {