From 90bc3ab770a892e66dc4a6625bac832048fdf2d7 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Tue, 7 Jun 2022 14:07:39 +0530
Subject: [PATCH] Function to create a randomly named UNIX domain socket

---
 kitty/child-monitor.c     | 17 ++++++++++++++-
 kitty/fast_data_types.pyi |  4 ++++
 kitty/utils.py            | 44 ++++++++++++++++++++++++++++++++++-----
 3 files changed, 59 insertions(+), 6 deletions(-)

diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
index d9faef67e..e38c02d85 100644
--- a/kitty/child-monitor.c
+++ b/kitty/child-monitor.c
@@ -20,6 +20,7 @@
 #include <sys/ioctl.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
+#include <sys/un.h>
 #include <signal.h>
 extern PyTypeObject Screen_Type;
 
@@ -1756,7 +1757,6 @@ cocoa_set_menubar_title(PyObject *self UNUSED, PyObject *args UNUSED) {
 }
 
 static PyObject*
-
 send_data_to_peer(PyObject *self UNUSED, PyObject *args) {
     char * msg; Py_ssize_t sz;
     unsigned long long peer_id;
@@ -1765,8 +1765,23 @@ send_data_to_peer(PyObject *self UNUSED, PyObject *args) {
     Py_RETURN_NONE;
 }
 
+static PyObject *
+random_unix_socket(PyObject *self UNUSED, PyObject *args UNUSED) {
+	int fd, optval = 1;
+	struct sockaddr_un bind_addr = {.sun_family=AF_UNIX};
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (fd < 0) return PyErr_SetFromErrno(PyExc_OSError);
+	if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &optval, sizeof optval) != 0) goto fail;
+	if (bind(fd, (struct sockaddr *)&bind_addr, sizeof(sa_family_t)) != 0) goto fail;
+    return PyLong_FromLong((long)fd);
+fail:
+    safe_close(fd, __FILE__, __LINE__);
+    return PyErr_SetFromErrno(PyExc_OSError);
+}
+
 static PyMethodDef module_methods[] = {
     METHODB(safe_pipe, METH_VARARGS),
+    METHODB(random_unix_socket, METH_NOARGS),
     {"add_timer", (PyCFunction)add_python_timer, METH_VARARGS, ""},
     {"remove_timer", (PyCFunction)remove_python_timer, METH_VARARGS, ""},
     METHODB(monitor_pid, METH_VARARGS),
diff --git a/kitty/fast_data_types.pyi b/kitty/fast_data_types.pyi
index 6418a44fe..93c229951 100644
--- a/kitty/fast_data_types.pyi
+++ b/kitty/fast_data_types.pyi
@@ -1387,3 +1387,7 @@ def sigqueue(pid: int, signal: int, value: int) -> None:
 
 def establish_controlling_tty(ttyname: str, stdin: int, stdout: int, stderr: int) -> None:
     pass
+
+
+def random_unix_socket() -> int:
+    pass
diff --git a/kitty/utils.py b/kitty/utils.py
index 2cbb34568..7280d91be 100644
--- a/kitty/utils.py
+++ b/kitty/utils.py
@@ -372,15 +372,18 @@ class startup_notification_handler:
             end_startup_notification(self.ctx)
 
 
-def remove_socket_file(s: 'Socket', path: Optional[str] = None) -> None:
+def remove_socket_file(s: 'Socket', path: Optional[str] = None, is_dir: Optional[Callable[[str], None]] = None) -> None:
     with suppress(OSError):
         s.close()
     if path:
         with suppress(OSError):
-            os.unlink(path)
+            if is_dir:
+                is_dir(path)
+            else:
+                os.unlink(path)
 
 
-def unix_socket_paths(name: str, ext: str = '.lock') -> Generator[str, None, None]:
+def unix_socket_directories() -> Iterator[str]:
     import tempfile
     home = os.path.expanduser('~')
     candidates = [tempfile.gettempdir(), home]
@@ -389,8 +392,39 @@ def unix_socket_paths(name: str, ext: str = '.lock') -> Generator[str, None, Non
         candidates = [user_cache_dir(), '/Library/Caches']
     for loc in candidates:
         if os.access(loc, os.W_OK | os.R_OK | os.X_OK):
-            filename = ('.' if loc == home else '') + name + ext
-            yield os.path.join(loc, filename)
+            yield loc
+
+
+def unix_socket_paths(name: str, ext: str = '.lock') -> Generator[str, None, None]:
+    home = os.path.expanduser('~')
+    for loc in unix_socket_directories():
+        filename = ('.' if loc == home else '') + name + ext
+        yield os.path.join(loc, filename)
+
+
+def random_unix_socket() -> 'Socket':
+    import shutil
+    import socket
+    import stat
+    import tempfile
+
+    from kitty.fast_data_types import random_unix_socket as rus
+    try:
+        fd = rus()
+    except OSError:
+        for path in unix_socket_directories():
+            ans = socket.socket(family=socket.AF_UNIX, type=socket.SOCK_STREAM, proto=0)
+            tdir = tempfile.mkdtemp(prefix='.kitty-', dir=path)
+            atexit.register(remove_socket_file, ans, tdir, shutil.rmtree)
+            path = os.path.join(tdir, 's')
+            ans.bind(path)
+            os.chmod(path, stat.S_IRUSR | stat.S_IWUSR)
+            break
+    else:
+        ans = socket.socket(family=socket.AF_UNIX, type=socket.SOCK_STREAM, proto=0, fileno=fd)
+    ans.set_inheritable(False)
+    ans.setblocking(False)
+    return ans
 
 
 def single_instance_unix(name: str) -> bool: