Implement --listen-on option

kitty/boss.py

@@ -2,7 +2,9 @@
 # vim:fileencoding=utf-8
 # License: GPL v3 Copyright: 2016, Kovid Goyal <kovid at kovidgoyal.net>
 
+import atexit
 import re
+import socket
 from functools import partial
 from gettext import gettext as _
 from weakref import WeakValueDictionary
@@ -24,7 +26,8 @@ from .session import create_session
 from .tabs import SpecialWindow, SpecialWindowInstance, TabManager
 from .utils import (
     end_startup_notification, get_primary_selection, init_startup_notification,
-    open_url, safe_print, set_primary_selection, single_instance
+    open_url, remove_socket_file, safe_print, set_primary_selection,
+    single_instance
 )
 
 
@@ -33,6 +36,29 @@ def initialize_renderer():
     prerender()
 
 
+def listen_on(spec):
+    protocol, rest = spec.split(':', 1)
+    socket_path = None
+    if protocol == 'unix':
+        family = socket.AF_UNIX
+        address = rest
+        if address.startswith('@') and len(address) > 1:
+            address = '\0' + address[1:]
+        else:
+            socket_path = address
+    elif protocol in ('tcp', 'tcp6'):
+        family = socket.AF_INET if protocol == 'tcp' else socket.AF_INET6
+        host, port = rest.rsplit(':', 1)
+        address = host, int(port)
+    else:
+        raise ValueError('Unknown protocol in --listen-on value: {}'.format(spec))
+    s = socket.socket(family)
+    atexit.register(remove_socket_file, s, socket_path)
+    s.bind(address)
+    s.listen()
+    return s.fileno()
+
+
 class DumpCommands:  # {{{
 
     def __init__(self, args):
@@ -70,10 +96,13 @@ class Boss:
         self.shutting_down = False
         talk_fd = getattr(single_instance, 'socket', None)
         talk_fd = -1 if talk_fd is None else talk_fd.fileno()
+        listen_fd = -1
+        if opts.allow_remote_control and args.listen_on:
+            listen_fd = listen_on(args.listen_on)
         self.child_monitor = ChildMonitor(
             self.on_child_death,
             DumpCommands(args) if args.dump_commands or args.dump_bytes else None,
-            talk_fd
+            talk_fd, listen_fd
         )
         set_boss(self)
         self.current_font_size = opts.font_size

kitty/child-monitor.c

@@ -36,7 +36,7 @@ typedef struct {
     bool shutting_down;
     pthread_t io_thread, talk_thread;
 
-    int talk_fd;
+    int talk_fd, listen_fd;
     Message *messages;
     size_t messages_capacity, messages_count;
 } ChildMonitor;
@@ -120,11 +120,11 @@ static PyObject *
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     ChildMonitor *self;
     PyObject *dump_callback, *death_notify;
-    int talk_fd = -1;
+    int talk_fd = -1, listen_fd = -1;
     int ret;
 
     if (the_monitor) { PyErr_SetString(PyExc_RuntimeError, "Can have only a single ChildMonitor instance"); return NULL; }
-    if (!PyArg_ParseTuple(args, "OO|i", &death_notify, &dump_callback, &talk_fd)) return NULL;
+    if (!PyArg_ParseTuple(args, "OO|ii", &death_notify, &dump_callback, &talk_fd, &listen_fd)) return NULL;
     if ((ret = pthread_mutex_init(&children_lock, NULL)) != 0) {
         PyErr_Format(PyExc_RuntimeError, "Failed to create children_lock mutex: %s", strerror(ret));
         return NULL;
@@ -138,6 +138,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     if (siginterrupt(SIGTERM, false) != 0) return PyErr_SetFromErrno(PyExc_OSError);
     self = (ChildMonitor *)type->tp_alloc(type, 0);
     self->talk_fd = talk_fd;
+    self->listen_fd = listen_fd;
     if (self == NULL) return PyErr_NoMemory();
     self->death_notify = death_notify; Py_INCREF(death_notify);
     if (dump_callback != Py_None) {
@@ -191,7 +192,7 @@ static void send_response(int fd, const char *msg, size_t msg_sz);
 static PyObject *
 start(ChildMonitor *self) {
 #define start_doc "start() -> Start the I/O thread"
-    if (self->talk_fd > -1) {
+    if (self->talk_fd > -1 || self->listen_fd > -1) {
         if (pthread_create(&self->talk_thread, NULL, talk_loop, self) != 0) return PyErr_SetFromErrno(PyExc_OSError);
     }
     int ret = pthread_create(&self->io_thread, NULL, io_loop, self);

kitty/cli.py

@@ -84,6 +84,15 @@ with the same |_ --instance-group| will result in new windows being created
 in the first |_ {appname}| instance within that group
 
 
+--listen-on
+Tell kitty to listen on the specified UNIX socket or TCP port for control
+messages. For example, --listen-on=unix:/tmp/mykitty or
+--listen-on=tcp:localhost:12345. On Linux systems, you can also use abstract
+UNIX sockets, not associated with a file, like this: --listen-on=unix:@mykitty.
+Note that this option will be ignored, unless you set allow_remote_control to yes
+in kitty.conf
+
+
 # Debugging options
 
 --version -v