Xwayland: first draft, just start server for now

3 files changed, 319 insertions, 0 deletions

diff --git a/xwayland/meson.build b/xwayland/meson.build
new file mode 100644
index 00000000..d43ace9b
--- /dev/null
+++ b/xwayland/meson.build
@@ -0,0 +1,5 @@
+lib_wlr_xwayland = static_library('wlr_xwayland', files(
+    'sockets.c',
+    'xwayland.c',
+  ),
+  include_directories: wlr_inc)
diff --git a/xwayland/sockets.c b/xwayland/sockets.c
new file mode 100644
index 00000000..868d6ada
--- /dev/null
+++ b/xwayland/sockets.c
@@ -0,0 +1,144 @@
+#define _XOPEN_SOURCE 700
+#include <stdlib.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <errno.h>
+#include "wlr/util/log.h"
+#include "xwayland/internals.h"
+
+static const char *lock_fmt = "/tmp/.X%d-lock";
+static const char *socket_dir = "/tmp/.X11-unix";
+static const char *socket_fmt = "/tmp/.X11-unix/X%d";
+
+static int open_socket(struct sockaddr_un *addr, size_t path_size) {
+	int fd, rc;
+	socklen_t size = offsetof(struct sockaddr_un, sun_path) + path_size + 1;
+
+	fd = socket(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
+	if (fd < 0) {
+		wlr_log_errno(L_ERROR, "Failed to create socket %s", addr->sun_path);
+		return -1;
+	}
+
+	if (addr->sun_path[0]) {
+		unlink(addr->sun_path);
+	}
+	if (bind(fd, (struct sockaddr*)addr, size) < 0) {
+		rc = errno;
+		wlr_log_errno(L_ERROR, "Failed to bind socket %s", addr->sun_path);
+		goto cleanup;
+	}
+	if (listen(fd, 1) < 0) {
+		rc = errno;
+		wlr_log_errno(L_ERROR, "Failed to listen to socket %s", addr->sun_path);
+		goto cleanup;
+	}
+
+	return fd;
+
+cleanup:
+	close(fd);
+	if (addr->sun_path[0]) {
+		unlink(addr->sun_path);
+	}
+	errno = rc;
+	return -1;
+}
+
+static bool open_sockets(int socks[2], int display) {
+	struct sockaddr_un addr = { .sun_family = AF_LOCAL };
+	size_t path_size;
+
+	mkdir(socket_dir, 0777);
+
+	// TODO: non-linux apparently want another format
+	addr.sun_path[0] = 0;
+	path_size = snprintf(addr.sun_path + 1, sizeof(addr.sun_path) - 1, socket_fmt, display);
+	socks[0] = open_socket(&addr, path_size);
+	if (socks[0] < 0) {
+		return false;
+	}
+
+	path_size = snprintf(addr.sun_path, sizeof(addr.sun_path), socket_fmt, display);
+	socks[1] = open_socket(&addr, path_size);
+	if (socks[1] < 0) {
+		close(socks[0]);
+		socks[0] = -1;
+		return false;
+	}
+
+	return true;
+}
+
+void unlink_sockets(int display) {
+	char sun_path[64];
+
+	snprintf(sun_path, sizeof(sun_path), socket_fmt, display);
+	unlink(sun_path);
+}
+
+int open_display_sockets(int socks[2]) {
+	int lock_fd, display;
+	char lock_name[64];
+
+	for (display = 0; display <= 32; display++) {
+		snprintf(lock_name, sizeof(lock_name), lock_fmt, display);
+		if ((lock_fd = open(lock_name, O_WRONLY | O_CREAT | O_EXCL | O_CLOEXEC, 0444)) >= 0) {
+			if (!open_sockets(socks, display)) {
+				unlink(lock_name);
+				close(lock_fd);
+				continue;
+			}
+			char pid[12];
+			snprintf(pid, sizeof(pid), "%10d", getpid());
+			if (write(lock_fd, pid, sizeof(pid) - 1) != sizeof(pid) - 1) {
+				unlink(lock_name);
+				close(lock_fd);
+				continue;
+			}
+			close(lock_fd);
+			break;
+		}
+
+		if ((lock_fd = open(lock_name, O_RDONLY | O_CLOEXEC)) < 0) {
+			continue;
+		}
+
+		char pid[12] = { 0 }, *end_pid;
+		ssize_t bytes = read(lock_fd, pid, sizeof(pid) - 1);
+		close(lock_fd);
+
+		if (bytes != sizeof(pid) - 1) {
+			continue;
+		}
+		long int read_pid;
+		read_pid = strtol(pid, &end_pid, 10);
+		if (read_pid < 0 || read_pid > INT32_MAX || end_pid != pid + sizeof(pid)) {
+			continue;
+		}
+		errno = 0;
+		if (kill((pid_t)read_pid, 0) != 0 && errno == ESRCH) {
+			if (unlink(lock_name) != 0) {
+				continue;
+			}
+			// retry
+			display--;
+			continue;
+		}
+	}
+
+	if (display > 32) {
+		wlr_log(L_ERROR, "No display available in the first 33");
+		return -1;
+	}
+
+	return display;
+}
diff --git a/xwayland/xwayland.c b/xwayland/xwayland.c
new file mode 100644
index 00000000..49173ace
--- /dev/null
+++ b/xwayland/xwayland.c
@@ -0,0 +1,170 @@
+#define _XOPEN_SOURCE 700
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <time.h>
+#include <errno.h>
+#include <wayland-server.h>
+#include "wlr/util/log.h"
+#include "wlr/xwayland.h"
+#include "xwayland/internals.h"
+
+static void safe_close(int fd) {
+	if (fd >= 0) {
+		close(fd);
+	}
+}
+
+static int unset_cloexec(int fd) {
+	if (fcntl(fd, F_SETFD, 0) != 0) {
+		wlr_log_errno(L_ERROR, "fcntl() failed on fd %d", fd);
+		return -1;
+	}
+	return 0;
+}
+
+static void exec_xwayland(struct wlr_xwayland *wlr_xwayland) {
+	if (unset_cloexec(wlr_xwayland->x_fd[0]) ||
+			unset_cloexec(wlr_xwayland->x_fd[1]) ||
+			unset_cloexec(wlr_xwayland->wm_fd[1]) ||
+			unset_cloexec(wlr_xwayland->wl_fd[1])) {
+		exit(EXIT_FAILURE);
+	}
+
+	char *argv[11] = { 0 };
+	argv[0] = "Xwayland";
+	if (asprintf(&argv[1], ":%d", wlr_xwayland->display) < 0) {
+		wlr_log_errno(L_ERROR, "asprintf failed");
+		exit(EXIT_FAILURE);
+	}
+	argv[2] = "-rootless";
+	argv[3] = "-terminate";
+	argv[4] = "-listen";
+	if (asprintf(&argv[5], "%d", wlr_xwayland->x_fd[0]) < 0) {
+		wlr_log_errno(L_ERROR, "asprintf failed");
+		exit(EXIT_FAILURE);
+	}
+	argv[6] = "-listen";
+	if (asprintf(&argv[7], "%d", wlr_xwayland->x_fd[1]) < 0) {
+		wlr_log_errno(L_ERROR, "asprintf failed");
+		exit(EXIT_FAILURE);
+	}
+	argv[8] = "-wm";
+	if (asprintf(&argv[9], "%d", wlr_xwayland->wm_fd[1]) < 0) {
+		wlr_log_errno(L_ERROR, "asprintf failed");
+		exit(EXIT_FAILURE);
+	}
+
+	const char *xdg_runtime = getenv("XDG_RUNTIME_DIR");
+	if (!xdg_runtime) {
+		wlr_log(L_ERROR, "XDG_RUNTIME_DIR is not set");
+		exit(EXIT_FAILURE);
+	}
+
+	char *envp[3] = { 0 };
+	if (asprintf(&envp[0], "XDG_RUNTIME_DIR=%s", xdg_runtime) < 0 ||
+			asprintf(&envp[1], "WAYLAND_SOCKET=%d", wlr_xwayland->wl_fd[1]) < 0) {
+		wlr_log_errno(L_ERROR, "asprintf failed");
+		exit(EXIT_FAILURE);
+	}
+
+	wlr_log(L_INFO, "Xwayland :%d -rootless -terminate -listen %d -listen %d -wm %d",
+			wlr_xwayland->display, wlr_xwayland->x_fd[0], wlr_xwayland->x_fd[1],
+			wlr_xwayland->wm_fd[1]);
+
+	execvpe("Xwayland", argv, envp);
+}
+
+static void xwayland_destroy_event(struct wl_listener *listener, void *data) {
+	struct wl_client *client = data;
+	struct wlr_xwayland *wlr_xwayland = wl_container_of(client, wlr_xwayland, client);
+
+	/* don't call client destroy */
+	wlr_xwayland->client = NULL;
+	wlr_xwayland_finish(wlr_xwayland);
+
+	if (wlr_xwayland->server_start - time(NULL) > 5) {
+		wlr_xwayland_init(wlr_xwayland, wlr_xwayland->wl_display);
+	}
+}
+
+static struct wl_listener xwayland_destroy_listener = {
+	.notify = xwayland_destroy_event,
+};
+
+void wlr_xwayland_finish(struct wlr_xwayland *wlr_xwayland) {
+
+	if (wlr_xwayland->client) {
+		wl_list_remove(&xwayland_destroy_listener.link);
+		wl_client_destroy(wlr_xwayland->client);
+	}
+
+	safe_close(wlr_xwayland->x_fd[0]);
+	safe_close(wlr_xwayland->x_fd[1]);
+	safe_close(wlr_xwayland->wl_fd[0]);
+	safe_close(wlr_xwayland->wl_fd[1]);
+	safe_close(wlr_xwayland->wm_fd[0]);
+	safe_close(wlr_xwayland->wm_fd[1]);
+
+	unlink_sockets(wlr_xwayland->display);	
+	unsetenv("DISPLAY");
+	/* kill Xwayland process? */
+}
+
+bool wlr_xwayland_init(struct wlr_xwayland *wlr_xwayland,
+		struct wl_display *wl_display) {
+	wlr_xwayland->wl_display = wl_display;
+	wlr_xwayland->x_fd[0] = wlr_xwayland->x_fd[1] = -1;
+	wlr_xwayland->wl_fd[0] = wlr_xwayland->wl_fd[1] = -1;
+	wlr_xwayland->wm_fd[0] = wlr_xwayland->wm_fd[1] = -1;
+
+	wlr_xwayland->display = open_display_sockets(wlr_xwayland->x_fd);
+	if (wlr_xwayland->display < 0) {
+		wlr_xwayland_finish(wlr_xwayland);
+		return false;
+	}
+	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, wlr_xwayland->wl_fd) != 0 ||
+			socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, wlr_xwayland->wm_fd) != 0) {
+		wlr_log_errno(L_ERROR, "failed to create socketpair");
+		wlr_xwayland_finish(wlr_xwayland);
+		return false;
+	}
+
+	if ((wlr_xwayland->pid = fork()) == 0) {
+		exec_xwayland(wlr_xwayland);
+		wlr_log_errno(L_ERROR, "execvpe failed");
+		exit(EXIT_FAILURE);
+	}
+
+	if (wlr_xwayland->pid < 0) {
+		wlr_log_errno(L_ERROR, "fork failed");
+		wlr_xwayland_finish(wlr_xwayland);
+		return false;
+	}
+
+	/* close child fds */
+	close(wlr_xwayland->x_fd[0]);
+	close(wlr_xwayland->x_fd[1]);
+	close(wlr_xwayland->wl_fd[1]);
+	close(wlr_xwayland->wm_fd[1]);
+	wlr_xwayland->x_fd[0] = wlr_xwayland->x_fd[1] = -1;
+	wlr_xwayland->wl_fd[1] = wlr_xwayland->wm_fd[1] = -1;
+
+	char display_name[16];
+	snprintf(display_name, sizeof(display_name), ":%d", wlr_xwayland->display);
+	setenv("DISPLAY", display_name, true);
+	wlr_xwayland->server_start = time(NULL);
+
+	if (!(wlr_xwayland->client = wl_client_create(wl_display, wlr_xwayland->wl_fd[0]))) {
+		wlr_log_errno(L_ERROR, "wl_client_create failed");
+		wlr_xwayland_finish(wlr_xwayland);
+	}
+
+	wl_client_add_destroy_listener(wlr_xwayland->client, &xwayland_destroy_listener);
+
+	return true;
+}