窗口管理器状态机设计

src/wm.c

@@ -0,0 +1,161 @@
+#include "wm.h"
+
+#include <glib-unix.h>
+#include <glib.h>
+#include <glibconfig.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <xcb/randr.h>
+#include <xcb/xcb.h>
+#include <xcb/xcb_aux.h>
+#include <xcb/xfixes.h>
+#include <xcb/xinerama.h>
+#include <xcb/xproto.h>
+
+#include "backtrace.h"
+#include "buffer.h"
+#include "utils.h"
+
+static void wm_setup_signal(void);
+static void wm_check_other_wm(void);
+static void wm_check_xcb_extensions(void);
+static void wm_detect_monitor(void);
+static void wm_scan_clients(void);
+
+wm_t wm;
+
+/** argv used to run wm */
+static char **cmd_argv;
+
+/** A pipe that is used to asynchronously handle SIGCHLD */
+static int sigchld_pipe[2];
+
+static void wm_atexit(bool restart) { wm.need_restart = restart; }
+
+static gboolean restart_on_signal(gpointer data) {
+  wm_restart();
+  return TRUE;
+}
+
+static gboolean exit_on_signal(gpointer data) {
+  g_main_loop_quit(wm.loop);
+  return TRUE;
+}
+
+static void signal_fatal(int signal_number) {
+  buffer_t buffer;
+  backtrace_get(&buffer);
+  fatal("signal %d, dumping backtrace\n%s", signal_number, buffer.s);
+}
+
+/* Signal handler for SIGCHLD. Causes reap_children() to be called. */
+static void signal_child(int signum) {
+  assert(signum == SIGCHLD);
+  int res = write(sigchld_pipe[1], " ", 1);
+  (void)res;
+  assert(res == 1);
+}
+
+void wm_setup_signal(void) {
+  g_unix_signal_add(SIGINT, exit_on_signal, NULL);
+  g_unix_signal_add(SIGTERM, exit_on_signal, NULL);
+  g_unix_signal_add(SIGHUP, restart_on_signal, NULL);
+
+  struct sigaction sa = {.sa_handler = signal_fatal, .sa_flags = SA_RESETHAND};
+  sigemptyset(&sa.sa_mask);
+  sigaction(SIGABRT, &sa, 0);
+  sigaction(SIGBUS, &sa, 0);
+  sigaction(SIGFPE, &sa, 0);
+  sigaction(SIGILL, &sa, 0);
+  sigaction(SIGSEGV, &sa, 0);
+  signal(SIGPIPE, SIG_IGN);
+
+  sa.sa_handler = signal_child;
+  sa.sa_flags = SA_NOCLDSTOP | SA_RESTART;
+  sigaction(SIGCHLD, &sa, 0);
+}
+
+void wm_check_other_wm(void) {
+  /* connect X server */
+  int default_screen;
+  xcb_connection_t *conn = xcb_connect(NULL, &default_screen);
+  int xcb_conn_error = xcb_connection_has_error(conn);
+  if (xcb_conn_error) fatal("cannot open display (error %d)", xcb_conn_error);
+
+  xcb_screen_t *screen = xcb_aux_get_screen(conn, default_screen);
+  xcb_window_t root = screen->root;
+
+  /* check other window manager running */
+  uint32_t mask = XCB_CW_EVENT_MASK;
+  const xcb_params_cw_t params = {
+    .event_mask = XCB_EVENT_MASK_SUBSTRUCTURE_REDIRECT,
+  };
+  xcb_void_cookie_t cookie =
+    xcb_aux_change_window_attributes_checked(conn, root, mask, &params);
+  if (xcb_request_check(conn, cookie)) {
+    fatal(
+      "another window manager is already running (cannot select "
+      "SubstructureRedirect)");
+  }
+
+  wm.xcb_conn = conn;
+  wm.default_screen = default_screen;
+  wm.screen = screen;
+}
+
+void wm_check_xcb_extensions(void) {
+  xcb_prefetch_extension_data(wm.xcb_conn, &xcb_xfixes_id);
+  xcb_prefetch_extension_data(wm.xcb_conn, &xcb_xinerama_id);
+  xcb_prefetch_extension_data(wm.xcb_conn, &xcb_randr_id);
+
+  const xcb_query_extension_reply_t *query;
+  query = xcb_get_extension_data(wm.xcb_conn, &xcb_xfixes_id);
+  wm.have_xfixes = query && query->present;
+
+  query = xcb_get_extension_data(wm.xcb_conn, &xcb_xinerama_id);
+  wm.have_xinerama = query && query->present;
+
+  query = xcb_get_extension_data(wm.xcb_conn, &xcb_randr_id);
+  wm.have_randr = query && query->present;
+}
+
+void wm_detect_monitor(void) {}
+void wm_scan_clients(void) {}
+
+void wm_restart(void) {
+  wm_atexit(true);
+  execvp(cmd_argv[0], cmd_argv);
+  fatal("execv() failed: %s", strerror(errno));
+}
+
+void wm_quit(void) {
+  if (g_main_loop_is_running(wm.loop)) {
+    g_main_loop_quit(wm.loop);
+  }
+}
+
+int main(int argc, char *argv[]) {
+  p_clear(&wm, 1);
+  cmd_argv = argv;
+  wm_setup_signal();
+
+  wm_check_other_wm();
+  wm_check_xcb_extensions();
+
+  wm_detect_monitor();
+
+  if (wm.loop == NULL) {
+    wm.loop = g_main_loop_new(NULL, FALSE);
+    g_main_loop_run(wm.loop);
+  }
+  g_main_loop_unref(wm.loop);
+  wm.loop = NULL;
+
+  wm_atexit(false);
+
+  return EXIT_SUCCESS;
+}