1 files changed, 153 insertions, 0 deletions
diff --git a/xwayland/sockets.c b/xwayland/sockets.c
new file mode 100644
index 00000000..48bcc822
--- /dev/null
+++ b/xwayland/sockets.c
@@ -0,0 +1,153 @@
+#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 "sockets.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_DEBUG, "Failed to create socket %c%s",
+			addr->sun_path[0] ? addr->sun_path[0] : '@',
+			addr->sun_path + 1);
+		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_DEBUG, "Failed to bind socket %c%s",
+			addr->sun_path[0] ? addr->sun_path[0] : '@',
+			addr->sun_path + 1);
+		goto cleanup;
+	}
+	if (listen(fd, 1) < 0) {
+		rc = errno;
+		wlr_log_errno(L_DEBUG, "Failed to listen to socket %c%s",
+			addr->sun_path[0] ? addr->sun_path[0] : '@',
+			addr->sun_path + 1);
+		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_display_sockets(int display) {
+	char sun_path[64];
+
+	snprintf(sun_path, sizeof(sun_path), socket_fmt, display);
+	unlink(sun_path);
+
+	snprintf(sun_path, sizeof(sun_path), lock_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) - 2) {
+			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;
+}