From df05339d2a96d16ee59a78b16d000d57cb68e2b4 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Mon, 7 Jun 2021 20:51:45 +0530
Subject: [PATCH] Allow reloading config by sending the SIGUSR1 signal

---
 docs/conf.rst         |  4 ++--
 kitty/child-monitor.c | 35 ++++++++++++++++++++++++++---------
 kitty/loop-utils.c    |  2 +-
 3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/docs/conf.rst b/docs/conf.rst
index 960507568..0a0c1f6f9 100644
--- a/docs/conf.rst
+++ b/docs/conf.rst
@@ -11,8 +11,8 @@ possibilities.
 
 You can open the config file within kitty by pressing :sc:`edit_config_file`.
 You can reload the config file within kitty by pressing
-:sc:`reload_config_file`. You can also display the current configuration by
-pressing the :sc:`debug_config` key.
+:sc:`reload_config_file` or sending kitty the ``SIGUSR1`` signal.  You can also
+display the current configuration by pressing the :sc:`debug_config` key.
 
 .. _confloc:
 
diff --git a/kitty/child-monitor.c b/kitty/child-monitor.c
index 5f9cfa5ed..7c7c025e8 100644
--- a/kitty/child-monitor.c
+++ b/kitty/child-monitor.c
@@ -83,7 +83,7 @@ static unsigned long remove_notify[MAX_CHILDREN] = {0};
 static size_t add_queue_count = 0, remove_queue_count = 0;
 static struct pollfd fds[MAX_CHILDREN + EXTRA_FDS] = {{0}};
 static pthread_mutex_t children_lock, talk_lock;
-static bool kill_signal_received = false;
+static bool kill_signal_received = false, reload_config_signal_received = false;
 static ChildMonitor *the_monitor = NULL;
 
 typedef struct {
@@ -333,7 +333,7 @@ static bool
 parse_input(ChildMonitor *self) {
     // Parse all available input that was read in the I/O thread.
     size_t count = 0, remove_count = 0;
-    bool input_read = false;
+    bool input_read = false, reload_config_called = false;
     monotonic_t now = monotonic();
     children_mutex(lock);
     while (remove_queue_count) {
@@ -343,11 +343,17 @@ parse_input(ChildMonitor *self) {
         FREE_CHILD(remove_queue[remove_queue_count]);
     }
 
-    if (UNLIKELY(kill_signal_received)) {
-        global_state.quit_request = IMPERATIVE_CLOSE_REQUESTED;
-        global_state.has_pending_closes = true;
-        request_tick_callback();
-        kill_signal_received = false;
+    if (UNLIKELY(kill_signal_received || reload_config_signal_received)) {
+        if (kill_signal_received) {
+            global_state.quit_request = IMPERATIVE_CLOSE_REQUESTED;
+            global_state.has_pending_closes = true;
+            request_tick_callback();
+            kill_signal_received = false;
+        }
+        else if (reload_config_signal_received) {
+            reload_config_signal_received = false;
+            reload_config_called = true;
+        }
     } else {
         count = self->count;
         for (size_t i = 0; i < count; i++) {
@@ -402,6 +408,9 @@ parse_input(ChildMonitor *self) {
         }
         DECREF_CHILD(scratch[i]);
     }
+    if (reload_config_called) {
+        call_boss(load_config_file, "");
+    }
     return input_read;
 }
 
@@ -1145,7 +1154,7 @@ read_bytes(int fd, Screen *screen) {
 }
 
 
-typedef struct { bool kill_signal, child_died; } SignalSet;
+typedef struct { bool kill_signal, child_died, reload_config; } SignalSet;
 
 static void
 handle_signal(int signum, void *data) {
@@ -1158,6 +1167,9 @@ handle_signal(int signum, void *data) {
         case SIGCHLD:
             ss->child_died = true;
             break;
+        case SIGUSR1:
+            ss->reload_config = true;
+            break;
         default:
             break;
     }
@@ -1272,7 +1284,12 @@ io_loop(void *data) {
                 SignalSet ss = {0};
                 data_received = true;
                 read_signals(fds[1].fd, handle_signal, &ss);
-                if (ss.kill_signal) { children_mutex(lock); kill_signal_received = true; children_mutex(unlock); }
+                if (ss.kill_signal || ss.reload_config) {
+                    children_mutex(lock);
+                    if (ss.kill_signal) kill_signal_received = true;
+                    if (ss.reload_config) reload_config_signal_received = true;
+                    children_mutex(unlock);
+                }
                 if (ss.child_died) reap_children(self, OPT(close_on_child_death));
             }
             for (i = 0; i < self->count; i++) {
diff --git a/kitty/loop-utils.c b/kitty/loop-utils.c
index abe0faf70..cf4a9dc65 100644
--- a/kitty/loop-utils.c
+++ b/kitty/loop-utils.c
@@ -45,7 +45,7 @@ handle_signal(int sig_num) {
 #define SIGNAL_SET \
     sigset_t signals = {0}; \
     sigemptyset(&signals); \
-    sigaddset(&signals, SIGINT); sigaddset(&signals, SIGTERM); sigaddset(&signals, SIGCHLD); \
+    sigaddset(&signals, SIGINT); sigaddset(&signals, SIGTERM); sigaddset(&signals, SIGCHLD); sigaddset(&signals, SIGUSR1); \
 
 void
 free_loop_data(LoopData *ld) {