aboutsummaryrefslogtreecommitdiff
path: root/xwayland/server.c
blob: d0057c66a2bebf4461b17edd4182cc072093c715 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
#define _POSIX_C_SOURCE 200809L
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <wayland-server-core.h>
#include <wlr/util/log.h>
#include <wlr/xwayland.h>
#include "sockets.h"
#include "util/signal.h"

static void safe_close(int fd) {
	if (fd >= 0) {
		close(fd);
	}
}

static int fill_arg(char ***argv, const char *fmt, ...) {
	int len;
	char **cur_arg = *argv;
	va_list args;
	va_start(args, fmt);
	len = vsnprintf(NULL, 0, fmt, args) + 1;
	va_end(args);
	while (*cur_arg) {
		cur_arg++;
	}
	*cur_arg = malloc(len);
	if (!*cur_arg) {
		return -1;
	}
	*argv = cur_arg;
	va_start(args, fmt);
	len = vsnprintf(*cur_arg, len, fmt, args);
	va_end(args);
	return len;
}

noreturn static void exec_xwayland(struct wlr_xwayland_server *server) {
	if (!set_cloexec(server->x_fd[0], false) ||
			!set_cloexec(server->x_fd[1], false) ||
			!set_cloexec(server->wl_fd[1], false)) {
		wlr_log(WLR_ERROR, "Failed to unset CLOEXEC on FD");
		_exit(EXIT_FAILURE);
	}
	if (server->enable_wm && !set_cloexec(server->wm_fd[1], false)) {
		wlr_log(WLR_ERROR, "Failed to unset CLOEXEC on FD");
		_exit(EXIT_FAILURE);
	}

	/* Make Xwayland signal us when it's ready */
	signal(SIGUSR1, SIG_IGN);

	char *argv[] = {
		"Xwayland", NULL /* display, e.g. :1 */,
		"-rootless", "-terminate",
		"-listen", NULL /* x_fd[0] */,
		"-listen", NULL /* x_fd[1] */,
		"-wm", NULL /* wm_fd[1] */,
		NULL,
	};
	char **cur_arg = argv;

	if (fill_arg(&cur_arg, ":%d", server->display) < 0 ||
			fill_arg(&cur_arg, "%d", server->x_fd[0]) < 0 ||
			fill_arg(&cur_arg, "%d", server->x_fd[1]) < 0) {
		wlr_log_errno(WLR_ERROR, "alloc/print failure");
		_exit(EXIT_FAILURE);
	}
	if (server->enable_wm) {
		if (fill_arg(&cur_arg, "%d", server->wm_fd[1]) < 0) {
			wlr_log_errno(WLR_ERROR, "alloc/print failure");
			_exit(EXIT_FAILURE);
		}
	} else {
		cur_arg++;
		*cur_arg = NULL;
	}

	char wayland_socket_str[16];
	snprintf(wayland_socket_str, sizeof(wayland_socket_str), "%d", server->wl_fd[1]);
	setenv("WAYLAND_SOCKET", wayland_socket_str, true);

	wlr_log(WLR_INFO, "WAYLAND_SOCKET=%d Xwayland :%d -rootless -terminate -listen %d -listen %d -wm %d",
		server->wl_fd[1], server->display, server->x_fd[0],
		server->x_fd[1], server->wm_fd[1]);

	// Closes stdout/stderr depending on log verbosity
	enum wlr_log_importance verbosity = wlr_log_get_verbosity();
	int devnull = open("/dev/null", O_WRONLY | O_CREAT | O_CLOEXEC, 0666);
	if (devnull < 0) {
		wlr_log_errno(WLR_ERROR, "XWayland: failed to open /dev/null");
		_exit(EXIT_FAILURE);
	}
	if (verbosity < WLR_INFO) {
		dup2(devnull, STDOUT_FILENO);
	}
	if (verbosity < WLR_ERROR) {
		dup2(devnull, STDERR_FILENO);
	}

	const char *xwayland_path = getenv("WLR_XWAYLAND");
	if (xwayland_path) {
		wlr_log(WLR_INFO, "Using Xwayland binary '%s' due to WLR_XWAYLAND",
			xwayland_path);
	} else {
		xwayland_path = "Xwayland";
	}

	// This returns if and only if the call fails
	execvp(xwayland_path, argv);

	wlr_log_errno(WLR_ERROR, "failed to exec Xwayland");
	close(devnull);
	_exit(EXIT_FAILURE);
}

static void server_finish_process(struct wlr_xwayland_server *server) {
	if (!server || server->display == -1) {
		return;
	}

	if (server->x_fd_read_event[0]) {
		wl_event_source_remove(server->x_fd_read_event[0]);
		wl_event_source_remove(server->x_fd_read_event[1]);

		server->x_fd_read_event[0] = server->x_fd_read_event[1] = NULL;
	}

	if (server->client) {
		wl_list_remove(&server->client_destroy.link);
		wl_client_destroy(server->client);
	}
	if (server->sigusr1_source) {
		wl_event_source_remove(server->sigusr1_source);
	}

	safe_close(server->wl_fd[0]);
	safe_close(server->wl_fd[1]);
	safe_close(server->wm_fd[0]);
	safe_close(server->wm_fd[1]);
	memset(server, 0, offsetof(struct wlr_xwayland_server, display));
	server->wl_fd[0] = server->wl_fd[1] = -1;
	server->wm_fd[0] = server->wm_fd[1] = -1;

	/* We do not kill the Xwayland process, it dies to broken pipe
	 * after we close our side of the wm/wl fds. This is more reliable
	 * than trying to kill something that might no longer be Xwayland.
	 */
}

static void server_finish_display(struct wlr_xwayland_server *server) {
	if (!server) {
		return;
	}

	wl_list_remove(&server->display_destroy.link);

	if (server->display == -1) {
		return;
	}

	safe_close(server->x_fd[0]);
	safe_close(server->x_fd[1]);
	server->x_fd[0] = server->x_fd[1] = -1;

	unlink_display_sockets(server->display);
	server->display = -1;
	server->display_name[0] = '\0';
}

static bool server_start(struct wlr_xwayland_server *server);
static bool server_start_lazy(struct wlr_xwayland_server *server);

static void handle_client_destroy(struct wl_listener *listener, void *data) {
	struct wlr_xwayland_server *server =
		wl_container_of(listener, server, client_destroy);

	if (server->sigusr1_source) {
		// Xwayland failed to start, let the sigusr1 handler deal with it
		return;
	}

	// Don't call client destroy: it's being destroyed already
	server->client = NULL;
	wl_list_remove(&server->client_destroy.link);

	server_finish_process(server);

	if (time(NULL) - server->server_start > 5) {
		if (server->lazy) {
			wlr_log(WLR_INFO, "Restarting Xwayland (lazy)");
			server_start_lazy(server);
		} else  {
			wlr_log(WLR_INFO, "Restarting Xwayland");
			server_start(server);
		}
	}
}

static void handle_display_destroy(struct wl_listener *listener, void *data) {
	struct wlr_xwayland_server *server =
		wl_container_of(listener, server, display_destroy);

	// Don't call client destroy: the display is being destroyed, it's too late
	if (server->client) {
		server->client = NULL;
		wl_list_remove(&server->client_destroy.link);
	}

	wlr_xwayland_server_destroy(server);
}

static int xserver_handle_ready(int signal_number, void *data) {
	struct wlr_xwayland_server *server = data;

	int stat_val = -1;
	while (waitpid(server->pid, &stat_val, 0) < 0) {
		if (errno == EINTR) {
			continue;
		}
		wlr_log_errno(WLR_ERROR, "waitpid for Xwayland fork failed");
		goto error;
	}
	if (stat_val) {
		wlr_log(WLR_ERROR, "Xwayland startup failed, not setting up xwm");
		goto error;
	}
	wlr_log(WLR_DEBUG, "Xserver is ready");

	wl_event_source_remove(server->sigusr1_source);
	server->sigusr1_source = NULL;

	struct wlr_xwayland_server_ready_event event = {
		.server = server,
		.wm_fd = server->wm_fd[0],
	};
	wlr_signal_emit_safe(&server->events.ready, &event);

	return 1; /* wayland event loop dispatcher's count */

error:
	/* clean up */
	server_finish_process(server);
	server_finish_display(server);
	return 1;
}

static bool server_start_display(struct wlr_xwayland_server *server,
		struct wl_display *wl_display) {
	server->display_destroy.notify = handle_display_destroy;
	wl_display_add_destroy_listener(wl_display, &server->display_destroy);

	server->display = open_display_sockets(server->x_fd);
	if (server->display < 0) {
		server_finish_display(server);
		return false;
	}

	snprintf(server->display_name, sizeof(server->display_name),
		":%d", server->display);
	return true;
}

static bool server_start(struct wlr_xwayland_server *server) {
	if (socketpair(AF_UNIX, SOCK_STREAM, 0, server->wl_fd) != 0) {
		wlr_log_errno(WLR_ERROR, "socketpair failed");
		server_finish_process(server);
		return false;
	}
	if (!set_cloexec(server->wl_fd[0], true) ||
			!set_cloexec(server->wl_fd[1], true)) {
		wlr_log(WLR_ERROR, "Failed to set O_CLOEXEC on socket");
		server_finish_process(server);
		return false;
	}
	if (server->enable_wm) {
		if (socketpair(AF_UNIX, SOCK_STREAM, 0, server->wm_fd) != 0) {
			wlr_log_errno(WLR_ERROR, "socketpair failed");
			server_finish_process(server);
			return false;
		}
		if (!set_cloexec(server->wm_fd[0], true) ||
				!set_cloexec(server->wm_fd[1], true)) {
			wlr_log(WLR_ERROR, "Failed to set O_CLOEXEC on socket");
			server_finish_process(server);
			return false;
		}
	}

	server->server_start = time(NULL);

	server->client = wl_client_create(server->wl_display, server->wl_fd[0]);
	if (!server->client) {
		wlr_log_errno(WLR_ERROR, "wl_client_create failed");
		server_finish_process(server);
		return false;
	}

	server->wl_fd[0] = -1; /* not ours anymore */

	server->client_destroy.notify = handle_client_destroy;
	wl_client_add_destroy_listener(server->client, &server->client_destroy);

	struct wl_event_loop *loop = wl_display_get_event_loop(server->wl_display);
	server->sigusr1_source = wl_event_loop_add_signal(loop, SIGUSR1,
		xserver_handle_ready, server);

	server->pid = fork();
	if (server->pid < 0) {
		wlr_log_errno(WLR_ERROR, "fork failed");
		server_finish_process(server);
		return false;
	} else if (server->pid == 0) {
		/* Double-fork, but we need to forward SIGUSR1 once Xserver(1)
		 * is ready, or error if there was one. */
		pid_t ppid = getppid();
		sigset_t sigset;
		sigemptyset(&sigset);
		sigaddset(&sigset, SIGUSR1);
		sigaddset(&sigset, SIGCHLD);
		sigprocmask(SIG_BLOCK, &sigset, NULL);

		pid_t pid = fork();
		if (pid < 0) {
			wlr_log_errno(WLR_ERROR, "second fork failed");
			_exit(EXIT_FAILURE);
		} else if (pid == 0) {
			exec_xwayland(server);
		}

		int sig;
		sigwait(&sigset, &sig);
		kill(ppid, SIGUSR1);
		wlr_log(WLR_DEBUG, "sent SIGUSR1 to process %d", ppid);
		if (sig == SIGCHLD) {
			waitpid(pid, NULL, 0);
			_exit(EXIT_FAILURE);
		}

		_exit(EXIT_SUCCESS);
	}

	/* close child fds */
	/* remain managing x sockets for lazy start */
	close(server->wl_fd[1]);
	safe_close(server->wm_fd[1]);
	server->wl_fd[1] = server->wm_fd[1] = -1;

	return true;
}

static int xwayland_socket_connected(int fd, uint32_t mask, void *data) {
	struct wlr_xwayland_server *server = data;

	wl_event_source_remove(server->x_fd_read_event[0]);
	wl_event_source_remove(server->x_fd_read_event[1]);
	server->x_fd_read_event[0] = server->x_fd_read_event[1] = NULL;

	server_start(server);

	return 0;
}

static bool server_start_lazy(struct wlr_xwayland_server *server) {
	struct wl_event_loop *loop = wl_display_get_event_loop(server->wl_display);

	if (!(server->x_fd_read_event[0] = wl_event_loop_add_fd(loop, server->x_fd[0],
				WL_EVENT_READABLE, xwayland_socket_connected, server))) {
		return false;
	}

	if (!(server->x_fd_read_event[1] = wl_event_loop_add_fd(loop, server->x_fd[1],
				WL_EVENT_READABLE, xwayland_socket_connected, server))) {
		wl_event_source_remove(server->x_fd_read_event[0]);
		server->x_fd_read_event[0] = NULL;
		return false;
	}

	return true;
}

void wlr_xwayland_server_destroy(struct wlr_xwayland_server *server) {
	if (!server) {
		return;
	}

	server_finish_process(server);
	server_finish_display(server);
	wlr_signal_emit_safe(&server->events.destroy, NULL);
	free(server);
}

struct wlr_xwayland_server *wlr_xwayland_server_create(
		struct wl_display *wl_display,
		struct wlr_xwayland_server_options *options) {
	struct wlr_xwayland_server *server =
		calloc(1, sizeof(struct wlr_xwayland_server));
	if (!server) {
		return NULL;
	}

	server->wl_display = wl_display;
	server->lazy = options->lazy;
	server->enable_wm = options->enable_wm;

	server->x_fd[0] = server->x_fd[1] = -1;
	server->wl_fd[0] = server->wl_fd[1] = -1;
	server->wm_fd[0] = server->wm_fd[1] = -1;

	wl_signal_init(&server->events.ready);
	wl_signal_init(&server->events.destroy);

	if (!server_start_display(server, wl_display)) {
		goto error_alloc;
	}

	if (server->lazy) {
		if (!server_start_lazy(server)) {
			goto error_display;
		}
	} else {
		if (!server_start(server)) {
			goto error_display;
		}
	}

	return server;

error_display:
	server_finish_display(server);
error_alloc:
	free(server);
	return NULL;
}