Report the current foreground processes as well as the original child process, when using kitty @ ls

docs/changelog.rst

@@ -10,6 +10,9 @@ Changelog
   are formatted. In particular the template can be used to display
   the tab number next to the title (:iss:`1223`)
 
+- Report the current foreground processes as well as the original child process,
+  when using `kitty @ ls`
+
 - Fix setting :opt:`background_opacity` causing window margins/padding to be slightly
   different shade from background (:iss:`1221`)
 

kitty/boss.py

@@ -10,6 +10,7 @@ from functools import partial
 from gettext import gettext as _
 from weakref import WeakValueDictionary
 
+from .child import cached_process_data
 from .cli import create_opts, parse_args
 from .conf.utils import to_cmdline
 from .config import initial_window_size_func, prepare_config_file_for_editing
@@ -150,14 +151,15 @@ class Boss:
         return os_window_id
 
     def list_os_windows(self):
-        active_tab, active_window = self.active_tab, self.active_window
-        active_tab_manager = self.active_tab_manager
-        for os_window_id, tm in self.os_window_map.items():
-            yield {
-                'id': os_window_id,
-                'is_focused': tm is active_tab_manager,
-                'tabs': list(tm.list_tabs(active_tab, active_window)),
-            }
+        with cached_process_data():
+            active_tab, active_window = self.active_tab, self.active_window
+            active_tab_manager = self.active_tab_manager
+            for os_window_id, tm in self.os_window_map.items():
+                yield {
+                    'id': os_window_id,
+                    'is_focused': tm is active_tab_manager,
+                    'tabs': list(tm.list_tabs(active_tab, active_window)),
+                }
 
     @property
     def all_tab_managers(self):

kitty/child.py

@@ -4,17 +4,28 @@
 
 import fcntl
 import os
+from collections import defaultdict
+from contextlib import contextmanager
 
 import kitty.fast_data_types as fast_data_types
 
 from .constants import is_macos, shell_path, terminfo_dir
 
 if is_macos:
-    from kitty.fast_data_types import cmdline_of_process, cwd_of_process as _cwd, environ_of_process as _environ_of_process
+    from kitty.fast_data_types import (
+            cmdline_of_process, cwd_of_process as _cwd, environ_of_process as _environ_of_process,
+            process_group_map as _process_group_map
+    )
 
     def cwd_of_process(pid):
         return os.path.realpath(_cwd(pid))
 
+    def process_group_map():
+        ans = defaultdict(list)
+        for pid, pgid in _process_group_map():
+            ans[pgid].append(pid)
+        return ans
+
 else:
 
     def cmdline_of_process(pid):
@@ -27,6 +38,46 @@ else:
     def _environ_of_process(pid):
         return open('/proc/{}/environ'.format(pid), 'rb').read().decode('utf-8')
 
+    def process_group_map():
+        ans = defaultdict(list)
+        for x in os.listdir('/proc'):
+            try:
+                pid = int(x)
+            except Exception:
+                continue
+            try:
+                raw = open('/proc/' + x + '/stat', 'rb').read().decode('utf-8')
+            except EnvironmentError:
+                continue
+            try:
+                q = int(raw.split(' ', 5)[4])
+            except Exception:
+                continue
+            ans[q].append(pid)
+        return ans
+
+
+def processes_in_group(grp):
+    gmap = getattr(process_group_map, 'cached_map', None)
+    if gmap is None:
+        try:
+            gmap = process_group_map()
+        except Exception:
+            gmap = {}
+    return gmap.get(grp, [])
+
+
+@contextmanager
+def cached_process_data():
+    try:
+        process_group_map.cached_map = process_group_map()
+    except Exception:
+        process_group_map.cached_map = {}
+    try:
+        yield
+    finally:
+        process_group_map.cached_map = None
+
 
 def parse_environ_block(data):
     """Parse a C environ block of environment variables into a dictionary."""
@@ -142,6 +193,24 @@ class Child:
         os.close(self.terminal_ready_fd)
         self.terminal_ready_fd = -1
 
+    @property
+    def foreground_processes(self):
+        try:
+            pgrp = os.tcgetpgrp(self.child_fd)
+            foreground_processes = processes_in_group(pgrp) if pgrp >= 0 else []
+
+            def process_desc(pid):
+                ans = {'pid': pid}
+                try:
+                    ans['cmdline'] = cmdline_of_process(pid)
+                except Exception:
+                    pass
+                return ans
+
+            return list(map(process_desc, foreground_processes))
+        except Exception:
+            return []
+
     @property
     def cmdline(self):
         try:

kitty/data-types.c

@@ -40,6 +40,7 @@
 #define NS_TO_US (1000)
 
 #ifdef __APPLE__
+#include <libproc.h>
 #include <mach/mach_time.h>
 static mach_timebase_info_data_t timebase = {0};
 
@@ -54,6 +55,25 @@ user_cache_dir() {
     return PyUnicode_FromString(buf);
 }
 
+static PyObject*
+process_group_map() {
+    int num_of_processes = proc_listallpids(NULL, 0);
+    size_t bufsize = sizeof(pid_t) * (num_of_processes + 1024);
+    pid_t *buf = malloc(bufsize);
+    if (!buf) return PyErr_NoMemory();
+    num_of_processes = proc_listallpids(buf, (int)bufsize);
+    PyObject *ans = PyTuple_New(num_of_processes);
+    if (ans == NULL) { free(buf); return PyErr_NoMemory(); }
+    for (int i = 0; i < num_of_processes; i++) {
+        long pid = buf[i], pgid = getpgid(buf[i]);
+        PyObject *t = Py_BuildValue("ll", pid, pgid);
+        if (t == NULL) { free(buf); Py_DECREF(ans); return NULL; }
+        PyTuple_SET_ITEM(ans, i, t);
+    }
+    free(buf);
+    return ans;
+}
+
 #else
 #include <time.h>
 static inline double monotonic_() {
@@ -177,6 +197,7 @@ static PyMethodDef module_methods[] = {
     {"redirect_std_streams", (PyCFunction)redirect_std_streams, METH_VARARGS, ""},
 #ifdef __APPLE__
     METHODB(user_cache_dir, METH_NOARGS),
+    METHODB(process_group_map, METH_NOARGS),
 #endif
 #ifdef WITH_PROFILER
     {"start_profiler", (PyCFunction)start_profiler, METH_VARARGS, ""},

kitty/window.py

@@ -168,6 +168,7 @@ class Window:
             cwd=self.child.current_cwd or self.child.cwd,
             cmdline=self.child.cmdline,
             env=self.child.environ,
+            foreground_processes=self.child.foreground_processes
         )
 
     @property