Implement live-reload of config colors on SIGUSR1.

config.c

@@ -3276,6 +3276,7 @@ config_load(struct config *conf, const char *conf_path,
     enum fcft_capabilities fcft_caps = fcft_capabilities();
 
     *conf = (struct config) {
+        .path = NULL,
         .term = xstrdup(FOOT_DEFAULT_TERM),
         .shell = get_shell(),
         .title = xstrdup("foot"),
@@ -3517,6 +3518,8 @@ config_load(struct config *conf, const char *conf_path,
     if (conf_file.path && conf_file.fd >= 0) {
         LOG_INFO("loading configuration from %s", conf_file.path);
 
+        conf->path = xstrdup(conf_file.path);
+
         FILE *f = fdopen(conf_file.fd, "r");
         if (f == NULL) {
             LOG_AND_NOTIFY_ERRNO("%s: failed to open", conf_file.path);
@@ -3788,6 +3791,20 @@ config_clone(const struct config *old)
     return conf;
 }
 
+void
+config_reload_colors(struct config *conf)
+{
+    user_notifications_t notifications = tll_init();
+    config_override_t overrides = tll_init();
+    struct config new_conf = {NULL};
+    config_load(&new_conf, conf->path, &notifications, &overrides, false, false);
+
+    // TODO: should we do something with any notifications that come from
+    // loading the config?
+
+    conf->colors = new_conf.colors;
+}
+
 UNITTEST
 {
     struct config original;
@@ -3816,6 +3833,7 @@ UNITTEST
 void
 config_free(struct config *conf)
 {
+    free(conf->path);
     free(conf->term);
     free(conf->shell);
     free(conf->title);

config.h

@@ -132,6 +132,7 @@ struct custom_regex {
 };
 
 struct config {
+    char *path;
     char *term;
     char *shell;
     char *title;
@@ -423,6 +424,7 @@ bool config_load(
     bool as_server);
 void config_free(struct config *conf);
 struct config *config_clone(const struct config *old);
+void config_reload_colors(struct config *conf);
 
 bool config_font_parse(const char *pattern, struct config_font *font);
 void config_font_list_destroy(struct config_font_list *font_list);

main.c

@@ -45,6 +45,20 @@ fdm_sigint(struct fdm *fdm, int signo, void *data)
     return true;
 }
 
+static bool
+fdm_sigusr1_server(struct fdm *fdm, int signo, void *data)
+{
+    server_hard_reload_config_colors(data);
+    return true;
+}
+
+static bool
+fdm_sigusr1_term(struct fdm *fdm, int signo, void *data)
+{
+    term_hard_reload_config_colors(data);
+    return true;
+}
+
 static void
 print_usage(const char *prog_name)
 {
@@ -608,6 +622,15 @@ main(int argc, char *const *argv)
         goto out;
     }
 
+    bool ok = as_server ?
+        fdm_signal_add(fdm, SIGUSR1, fdm_sigusr1_server, server)
+      : fdm_signal_add(fdm, SIGUSR1, fdm_sigusr1_term, term);
+    if (!ok) {
+        LOG_WARN("failed to set SIGUSR1 handler");
+        goto out;
+    }
+    LOG_INFO("added USR1 handler");
+
     struct sigaction sig_ign = {.sa_handler = SIG_IGN};
     sigemptyset(&sig_ign.sa_mask);
     if (sigaction(SIGHUP, &sig_ign, NULL) < 0 ||
@@ -645,6 +668,7 @@ out:
     reaper_destroy(reaper);
     fdm_signal_del(fdm, SIGTERM);
     fdm_signal_del(fdm, SIGINT);
+    fdm_signal_del(fdm, SIGUSR1);
     fdm_destroy(fdm);
 
     config_free(&conf);

server.c

@@ -591,6 +591,20 @@ err:
     return NULL;
 }
 
+/* Reload configured colors from disk. */
+void
+server_hard_reload_config_colors(struct server *server) {
+    config_reload_colors((struct config *)server->conf);
+
+    tll_foreach(server->wayl->terms, it) {
+        struct terminal *term = it->item;
+
+        ((struct config *)term->conf)->colors = server->conf->colors;
+
+        term_soft_reload_config_colors(term);
+    }
+}
+
 void
 server_destroy(struct server *server)
 {

server.h

@@ -9,3 +9,4 @@ struct server;
 struct server *server_init(const struct config *conf, struct fdm *fdm,
                            struct reaper *reaper, struct wayland *wayl);
 void server_destroy(struct server *server);
+void server_hard_reload_config_colors(struct server *server);

terminal.c

@@ -4693,3 +4693,28 @@ term_send_size_notification(struct terminal *term)
         term->rows, term->cols, height, width);
     term_to_slave(term, buf, n);
 }
+
+/* Reload configured colors from disk. */
+void
+term_hard_reload_config_colors(struct terminal *term) {
+    config_reload_colors((struct config *)term->conf);
+    term_soft_reload_config_colors(term);
+}
+
+/* Reset colors to the in-memory config values. Does not reload the config from
+   disk. */
+void
+term_soft_reload_config_colors(struct terminal *term) {
+    term->colors.fg = term->conf->colors.fg;
+    term->colors.bg = term->conf->colors.bg;
+    term->colors.alpha = term->conf->colors.alpha;
+    term->colors.cursor_fg = term->conf->cursor.color.text;
+    term->colors.cursor_bg = term->conf->cursor.color.cursor;
+    term->colors.selection_fg = term->conf->colors.selection_fg;
+    term->colors.selection_bg = term->conf->colors.selection_bg;
+
+    memcpy(term->colors.table, term->conf->colors.table, sizeof(term->colors.table));
+
+    term_damage_all(term);
+    render_refresh(term);
+}

terminal.h

@@ -982,6 +982,9 @@ void term_enable_size_notifications(struct terminal *term);
 void term_disable_size_notifications(struct terminal *term);
 void term_send_size_notification(struct terminal *term);
 
+void term_hard_reload_config_colors(struct terminal *term);
+void term_soft_reload_config_colors(struct terminal *term);
+
 static inline void term_reset_grapheme_state(struct terminal *term)
 {
 #if defined(FOOT_GRAPHEME_CLUSTERING)