Merge pull request #25 from ascent12/forking

Forking session backend

CMake/FindLibcap.cmake

@@ -0,0 +1,56 @@
+#.rst:
+# FindLibcap
+# -------
+#
+# Find Libcap library
+#
+# Try to find Libcap library. The following values are defined
+#
+# ::
+#
+#   Libcap_FOUND         - True if Libcap is available
+#   Libcap_INCLUDE_DIRS  - Include directories for Libcap
+#   Libcap_LIBRARIES     - List of libraries for Libcap
+#   Libcap_DEFINITIONS   - List of definitions for Libcap
+#
+# and also the following more fine grained variables
+#
+# ::
+#
+#   Libcap_VERSION
+#   Libcap_VERSION_MAJOR
+#   Libcap_VERSION_MINOR
+#
+#=============================================================================
+# Copyright (c) 2017 Jerzi Kaminsky
+#
+# Distributed under the OSI-approved BSD License (the "License");
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+
+include(FeatureSummary)
+set_package_properties(Libcap PROPERTIES
+   URL "https://www.kernel.org/pub/linux/libs/security/linux-privs/libcap2"
+   DESCRIPTION "Library for getting and setting POSIX.1e capabilities")
+
+find_package(PkgConfig)
+pkg_check_modules(PC_CAP QUIET Libcap)
+find_library(Libcap_LIBRARIES NAMES cap HINTS ${PC_CAP_LIBRARY_DIRS})
+find_path(Libcap_INCLUDE_DIRS sys/capability.h HINTS ${PC_CAP_INCLUDE_DIRS})
+
+set(Libcap_VERSION ${PC_CAP_VERSION})
+string(REPLACE "." ";" VERSION_LIST "${PC_CAP_VERSION}")
+
+LIST(LENGTH VERSION_LIST n)
+if (n EQUAL 2)
+   list(GET VERSION_LIST 0 Libcap_VERSION_MAJOR)
+   list(GET VERSION_LIST 1 Libcap_VERSION_MINOR)
+endif ()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Libcap DEFAULT_MSG Libcap_INCLUDE_DIRS Libcap_LIBRARIES)
+mark_as_advanced(Libcap_INCLUDE_DIRS Libcap_LIBRARIES Libcap_DEFINITIONS
+   Libcap_VERSION Libcap_VERSION_MAJOR Libcap_VERSION_MICRO Libcap_VERSION_MINOR)

CMakeLists.txt

@@ -50,6 +50,7 @@ find_package(GBM REQUIRED)
 find_package(LibInput REQUIRED)
 find_package(XKBCommon REQUIRED)
 find_package(Udev REQUIRED)
+find_package(Libcap)
 find_package(Systemd)
 
 include(Wayland)

README.md

@@ -18,6 +18,7 @@ Install dependencies:
 * libinput
 * udev
 * systemd (optional, for logind support)
+* libcap (optional, for capability support)
 * asciidoc (optional, for man pages)
 
 Run these commands:

examples/shared.c

@@ -466,6 +466,7 @@ void compositor_init(struct compositor_state *state) {
 	struct wlr_backend *wlr = wlr_backend_autocreate(
 			state->display, state->session);
 	if (!wlr) {
+		wlr_session_finish(state->session);
 		exit(1);
 	}
 	wl_signal_add(&wlr->events.input_add, &state->input_add);
@@ -477,10 +478,19 @@ void compositor_init(struct compositor_state *state) {
 	clock_gettime(CLOCK_MONOTONIC, &state->last_frame);
 
 	const char *socket = wl_display_add_socket_auto(state->display);
+	if (!socket) {
+		wlr_log_errno(L_ERROR, "Unable to open wayland socket");
+		wlr_backend_destroy(wlr);
+		wlr_session_finish(state->session);
+		exit(1);
+	}
+
 	wlr_log(L_INFO, "Running compositor on wayland display '%s'", socket);
 	setenv("_WAYLAND_DISPLAY", socket, true);
 	if (!wlr_backend_init(state->backend)) {
 		wlr_log(L_ERROR, "Failed to initialize backend");
+		wlr_backend_destroy(wlr);
+		wlr_session_finish(state->session);
 		exit(1);
 	}
 }

include/session/direct-ipc.h

@@ -0,0 +1,12 @@
+#ifndef SESSION_DIRECT_IPC
+#define SESSION_DIRECT_IPC
+
+#include <sys/types.h>
+
+int direct_ipc_open(int sock, const char *path);
+void direct_ipc_setmaster(int sock, int fd);
+void direct_ipc_dropmaster(int sock, int fd);
+void direct_ipc_finish(int sock, pid_t pid);
+int direct_ipc_start(pid_t *pid_out);
+
+#endif

include/wlr/session.h

@@ -9,16 +9,57 @@ struct session_impl;
 
 struct wlr_session {
 	const struct session_impl *impl;
-
-	bool active;
+	/*
+	 * Signal for when the session becomes active/inactive.
+	 * It's called when we swap virtual terminal.
+	 */
 	struct wl_signal session_signal;
+	bool active;
+
+	int drm_fd;
+	unsigned vtnr;
+	char seat[8];
 };
 
+/*
+ * Opens a session, taking control of the current virtual terminal.
+ * This should not be called if another program is already in control
+ * of the terminal (Xorg, another Wayland compositor, etc.).
+ *
+ * If logind support is not enabled, you must have CAP_SYS_ADMIN or be root.
+ * It is safe to drop priviledges after this is called.
+ *
+ * Returns NULL on error.
+ */
 struct wlr_session *wlr_session_start(struct wl_display *disp);
+
+/*
+ * Closes a previously opened session and restores the virtual terminal.
+ * You should call wlr_session_close_file on each files you opened
+ * with wlr_session_open_file before you call this.
+ */
 void wlr_session_finish(struct wlr_session *session);
-int wlr_session_open_file(struct wlr_session *restrict session,
-		const char *restrict path);
+
+/*
+ * Opens the file at path.
+ * This can only be used to open DRM or evdev (input) devices.
+ *
+ * When the session becomes inactive:
+ * - DRM files lose their DRM master status
+ * - evdev files become invalid and should be closed
+ *
+ * Returns -errno on error.
+ */
+int wlr_session_open_file(struct wlr_session *session, const char *path);
+
+/*
+ * Closes a file previously opened with wlr_session_open_file.
+ */
 void wlr_session_close_file(struct wlr_session *session, int fd);
-bool wlr_session_change_vt(struct wlr_session *session, int vt);
+
+/*
+ * Changes the virtual terminal.
+ */
+bool wlr_session_change_vt(struct wlr_session *session, unsigned vt);
 
 #endif

include/wlr/session/interface.h

@@ -6,10 +6,9 @@
 struct session_impl {
 	struct wlr_session *(*start)(struct wl_display *disp);
 	void (*finish)(struct wlr_session *session);
-	int (*open)(struct wlr_session *restrict session,
-			const char *restrict path);
+	int (*open)(struct wlr_session *session, const char *path);
 	void (*close)(struct wlr_session *session, int fd);
-	bool (*change_vt)(struct wlr_session *session, int vt);
+	bool (*change_vt)(struct wlr_session *session, unsigned vt);
 };
 
 #endif

session/CMakeLists.txt

@@ -1,10 +1,12 @@
 include_directories(
-	${WAYLAND_INCLUDE_DIR}
+    ${WAYLAND_INCLUDE_DIR}
+    ${DRM_INCLUDE_DIRS}
 )
 
 set(sources
     session.c
     direct.c
+    direct-ipc.c
 )
 
 set(libs
@@ -21,5 +23,13 @@ if (SYSTEMD_FOUND)
     list(APPEND libs ${SYSTEMD_LIBRARIES})
 endif ()
 
+if (Libcap_FOUND)
+    add_definitions(${Libcap_DEFINITIONS})
+    include_directories(${Libcap_INCLUDE_DIRS})
+
+    add_definitions(-DHAS_LIBCAP)
+    list(APPEND libs ${Libcap_LIBRARIES})
+endif ()
+
 add_library(wlr-session ${sources})
 target_link_libraries(wlr-session ${libs})

session/direct-ipc.c

@@ -0,0 +1,235 @@
+#define _POSIX_C_SOURCE 200809L
+#include <errno.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/sysmacros.h>
+#include <sys/wait.h>
+#include <xf86drm.h>
+#include <linux/major.h>
+#include <wlr/util/log.h>
+#include "session/direct-ipc.h"
+
+enum { DRM_MAJOR = 226 };
+
+#ifdef HAS_LIBCAP
+#include <sys/capability.h>
+
+static bool have_permissions(void) {
+	cap_t cap = cap_get_proc();
+	cap_flag_value_t val;
+
+	if (!cap || cap_get_flag(cap, CAP_SYS_ADMIN, CAP_PERMITTED, &val) || val != CAP_SET) {
+		wlr_log(L_ERROR, "Do not have CAP_SYS_ADMIN; cannot become DRM master");
+		cap_free(cap);
+		return false;
+	}
+
+	cap_free(cap);
+	return true;
+}
+#else
+static bool have_permissions(void) {
+	if (geteuid() != 0) {
+		wlr_log(L_ERROR, "Do not have root privileges; cannot become DRM master");
+		return false;
+	}
+
+	return true;
+}
+#endif
+
+static void send_msg(int sock, int fd, void *buf, size_t buf_len) {
+	char control[CMSG_SPACE(sizeof(fd))] = {0};
+	struct iovec iovec = { .iov_base = buf, .iov_len = buf_len };
+	struct msghdr msghdr = {0};
+
+	if (buf) {
+		msghdr.msg_iov = &iovec;
+		msghdr.msg_iovlen = 1;
+	}
+
+	if (fd >= 0) {
+		msghdr.msg_control = &control;
+		msghdr.msg_controllen = sizeof(control);
+
+		struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msghdr);
+		*cmsg = (struct cmsghdr) {
+			.cmsg_level = SOL_SOCKET,
+			.cmsg_type = SCM_RIGHTS,
+			.cmsg_len = CMSG_LEN(sizeof(fd)),
+		};
+		*(int *)CMSG_DATA(cmsg) = fd;
+	}
+
+	ssize_t ret;
+	do {
+		ret = sendmsg(sock, &msghdr, 0);
+	} while (ret < 0 && errno == EINTR);
+}
+
+static ssize_t recv_msg(int sock, int *fd_out, void *buf, size_t buf_len) {
+	char control[CMSG_SPACE(sizeof(*fd_out))] = {0};
+	struct iovec iovec = { .iov_base = buf, .iov_len = buf_len };
+	struct msghdr msghdr = {0};
+
+	if (buf) {
+		msghdr.msg_iov = &iovec;
+		msghdr.msg_iovlen = 1;
+	}
+
+	if (fd_out) {
+		msghdr.msg_control = &control;
+		msghdr.msg_controllen = sizeof(control);
+	}
+
+	ssize_t ret;
+	do {
+		ret = recvmsg(sock, &msghdr, MSG_CMSG_CLOEXEC);
+	} while (ret < 0 && errno == EINTR);
+
+	if (fd_out) {
+		struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msghdr);
+		*fd_out = cmsg ? *(int *)CMSG_DATA(cmsg) : -1;
+	}
+
+	return ret;
+}
+
+enum msg_type {
+	MSG_OPEN,
+	MSG_SETMASTER,
+	MSG_DROPMASTER,
+	MSG_END,
+};
+
+struct msg {
+	enum msg_type type;
+	char path[256];
+};
+
+static void communicate(int sock) {
+	struct msg msg;
+	int drm_fd = -1;
+	bool running = true;
+
+	while (running && recv_msg(sock, &drm_fd, &msg, sizeof(msg)) >= 0) {
+		switch (msg.type) {
+		case MSG_OPEN:
+			errno = 0;
+
+			// These are the same flags that logind opens files with
+			int fd = open(msg.path, O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+			int ret = errno;
+			if (fd == -1) {
+				goto error;
+			}
+
+			struct stat st;
+			if (fstat(fd, &st) < 0) {
+				ret = errno;
+				goto error;
+			}
+
+			uint32_t maj = major(st.st_rdev);
+			if (maj != INPUT_MAJOR && maj != DRM_MAJOR) {
+				ret = ENOTSUP;
+				goto error;
+			}
+
+			if (maj == DRM_MAJOR && drmSetMaster(fd)) {
+				ret = errno;
+			}
+error:
+			send_msg(sock, ret ? -1 : fd, &ret, sizeof(ret));
+			close(fd);
+
+			break;
+
+		case MSG_SETMASTER:
+			drmSetMaster(drm_fd);
+			close(drm_fd);
+			send_msg(sock, -1, NULL, 0);
+			break;
+
+		case MSG_DROPMASTER:
+			drmDropMaster(drm_fd);
+			close(drm_fd);
+			send_msg(sock, -1, NULL, 0);
+			break;
+
+		case MSG_END:
+			running = false;
+			send_msg(sock, -1, NULL, 0);
+			break;
+		}
+	}
+
+	close(sock);
+}
+
+int direct_ipc_open(int sock, const char *path) {
+	struct msg msg = { .type = MSG_OPEN };
+	snprintf(msg.path, sizeof(msg.path), "%s", path);
+
+	send_msg(sock, -1, &msg, sizeof(msg));
+
+	int fd, err;
+	recv_msg(sock, &fd, &err, sizeof(err));
+
+	return err ? -err : fd;
+}
+
+void direct_ipc_setmaster(int sock, int fd) {
+	struct msg msg = { .type = MSG_SETMASTER };
+
+	send_msg(sock, fd, &msg, sizeof(msg));
+	recv_msg(sock, NULL, NULL, 0);
+}
+
+void direct_ipc_dropmaster(int sock, int fd) {
+	struct msg msg = { .type = MSG_DROPMASTER };
+
+	send_msg(sock, fd, &msg, sizeof(msg));
+	recv_msg(sock, NULL, NULL, 0);
+}
+
+void direct_ipc_finish(int sock, pid_t pid) {
+	struct msg msg = { .type = MSG_END };
+
+	send_msg(sock, -1, &msg, sizeof(msg));
+	recv_msg(sock, NULL, NULL, 0);
+
+	waitpid(pid, NULL, 0);
+}
+
+int direct_ipc_start(pid_t *pid_out) {
+	if (!have_permissions()) {
+		return -1;
+	}
+
+	int sock[2];
+	if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sock) < 0) {
+		wlr_log_errno(L_ERROR, "Failed to create socket pair");
+		return -1;
+	}
+
+	pid_t pid = fork();
+	if (pid < 0) {
+		wlr_log_errno(L_ERROR, "Fork failed");
+		close(sock[0]);
+		close(sock[1]);
+		return -1;
+	} else if (pid == 0) {
+		close(sock[0]);
+		communicate(sock[1]);
+		_Exit(0);
+	}
+
+	close(sock[1]);
+	*pid_out = pid;
+	return sock[0];
+}

session/direct.c

@@ -1,53 +1,238 @@
 #define _POSIX_C_SOURCE 200809L
 #include <errno.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <stdbool.h>
-#include <string.h>
-#include <fcntl.h>
 #include <unistd.h>
+#include <signal.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <linux/kd.h>
+#include <linux/major.h>
+#include <linux/input.h>
+#include <linux/vt.h>
 #include <wayland-server.h>
 #include <wlr/session/interface.h>
 #include <wlr/util/log.h>
+#include "session/direct-ipc.h"
+
+enum { DRM_MAJOR = 226 };
 
 const struct session_impl session_direct;
 
 struct direct_session {
 	struct wlr_session base;
+	int tty_fd;
+	int old_kbmode;
+	int sock;
+	pid_t child;
+
+	struct wl_event_source *vt_source;
 };
 
-static int direct_session_open(struct wlr_session *restrict base,
-	const char *restrict path) {
-	return open(path, O_RDWR | O_CLOEXEC);
+static int direct_session_open(struct wlr_session *base, const char *path) {
+	struct direct_session *session = wl_container_of(base, session, base);
+
+	int fd = direct_ipc_open(session->sock, path);
+	if (fd < 0) {
+		wlr_log(L_ERROR, "Failed to open %s: %s%s", path, strerror(-fd),
+			fd == -EINVAL ? "; is another display server running?" : "");
+		return fd;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st) < 0) {
+		close(fd);
+		return -errno;
+	}
+
+	if (major(st.st_rdev) == DRM_MAJOR) {
+		session->base.drm_fd = fd;
+	}
+
+	return fd;
 }
 
 static void direct_session_close(struct wlr_session *base, int fd) {
+	struct direct_session *session = wl_container_of(base, session, base);
+
+	struct stat st;
+	if (fstat(fd, &st) < 0) {
+		wlr_log_errno(L_ERROR, "Stat failed");
+		close(fd);
+		return;
+	}
+
+	if (major(st.st_rdev) == DRM_MAJOR) {
+		direct_ipc_dropmaster(session->sock, session->base.drm_fd);
+		session->base.drm_fd = -1;
+	} else if (major(st.st_rdev) == INPUT_MAJOR) {
+		ioctl(fd, EVIOCREVOKE, 0);
+	}
+
 	close(fd);
 }
 
-static bool direct_change_vt(struct wlr_session *base, int vt) {
-	// TODO
-	return false;
+static bool direct_change_vt(struct wlr_session *base, unsigned vt) {
+	struct direct_session *session = wl_container_of(base, session, base);
+	return ioctl(session->tty_fd, VT_ACTIVATE, (int)vt) == 0;
 }
 
 static void direct_session_finish(struct wlr_session *base) {
 	struct direct_session *session = wl_container_of(base, session, base);
+	struct vt_mode mode = {
+		.mode = VT_AUTO,
+	};
 
+	errno = 0;
+
+	ioctl(session->tty_fd, KDSKBMODE, session->old_kbmode);
+	ioctl(session->tty_fd, KDSETMODE, KD_TEXT);
+	ioctl(session->tty_fd, VT_SETMODE, &mode);
+
+	if (errno) {
+		wlr_log(L_ERROR, "Failed to restore tty");
+	}
+
+	direct_ipc_finish(session->sock, session->child);
+	close(session->sock);
+
+	wl_event_source_remove(session->vt_source);
+	close(session->tty_fd);
 	free(session);
 }
 
+static int vt_handler(int signo, void *data) {
+	struct direct_session *session = data;
+
+	if (session->base.active) {
+		session->base.active = false;
+		wl_signal_emit(&session->base.session_signal, session);
+		direct_ipc_dropmaster(session->sock, session->base.drm_fd);
+		ioctl(session->tty_fd, VT_RELDISP, 1);
+	} else {
+		ioctl(session->tty_fd, VT_RELDISP, VT_ACKACQ);
+		direct_ipc_setmaster(session->sock, session->base.drm_fd);
+		session->base.active = true;
+		wl_signal_emit(&session->base.session_signal, session);
+	}
+
+	return 1;
+}
+
+static bool setup_tty(struct direct_session *session, struct wl_display *display) {
+	int fd = dup(STDIN_FILENO);
+	if (fd == -1) {
+		wlr_log_errno(L_ERROR, "Cannot open tty");
+		return false;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st) == -1 || major(st.st_rdev) != TTY_MAJOR || minor(st.st_rdev) == 0) {
+		wlr_log(L_ERROR, "Not running from a virtual terminal");
+		goto error;
+	}
+
+	int tty = minor(st.st_rdev);
+	int ret, kd_mode, old_kbmode;
+
+	ret = ioctl(fd, KDGETMODE, &kd_mode);
+	if (ret) {
+		wlr_log_errno(L_ERROR, "Failed to get tty mode");
+		goto error;
+	}
+
+	if (kd_mode != KD_TEXT) {
+		wlr_log(L_ERROR,
+			"tty already in graphics mode; is another display server running?");
+		goto error;
+	}
+
+	ioctl(fd, VT_ACTIVATE, tty);
+	ioctl(fd, VT_WAITACTIVE, tty);
+
+	if (ioctl(fd, KDGKBMODE, &old_kbmode)) {
+		wlr_log_errno(L_ERROR, "Failed to read keyboard mode");
+		goto error;
+	}
+
+	if (ioctl(fd, KDSKBMODE, K_OFF)) {
+		wlr_log_errno(L_ERROR, "Failed to set keyboard mode");
+		goto error;
+	}
+
+	if (ioctl(fd, KDSETMODE, KD_GRAPHICS)) {
+		wlr_log_errno(L_ERROR, "Failed to set graphics mode on tty");
+		goto error;
+	}
+
+	struct vt_mode mode = {
+		.mode = VT_PROCESS,
+		.relsig = SIGUSR1,
+		.acqsig = SIGUSR1,
+	};
+
+	if (ioctl(fd, VT_SETMODE, &mode) < 0) {
+		wlr_log(L_ERROR, "Failed to take control of tty");
+		goto error;
+	}
+
+	struct wl_event_loop *loop = wl_display_get_event_loop(display);
+	session->vt_source = wl_event_loop_add_signal(loop, SIGUSR1,
+		vt_handler, session);
+	if (!session->vt_source) {
+		goto error;
+	}
+
+	session->base.vtnr = tty;
+	session->tty_fd = fd;
+	session->old_kbmode = old_kbmode;
+
+	return true;
+
+error:
+	close(fd);
+	return false;
+}
+
 static struct wlr_session *direct_session_start(struct wl_display *disp) {
 	struct direct_session *session = calloc(1, sizeof(*session));
 	if (!session) {
-		wlr_log(L_ERROR, "Allocation failed: %s", strerror(errno));
+		wlr_log_errno(L_ERROR, "Allocation failed");
 		return NULL;
 	}
 
+	session->sock = direct_ipc_start(&session->child);
+	if (session->sock == -1) {
+		goto error_session;
+	}
+
+	if (!setup_tty(session, disp)) {
+		goto error_ipc;
+	}
+
+	// XXX: Is it okay to trust the environment like this?
+	const char *seat = getenv("XDG_SEAT");
+	if (!seat) {
+		seat = "seat0";
+	}
+
 	wlr_log(L_INFO, "Successfully loaded direct session");
 
+	snprintf(session->base.seat, sizeof(session->base.seat), "%s", seat);
+	session->base.drm_fd = -1;
 	session->base.impl = &session_direct;
 	session->base.active = true;
 	wl_signal_init(&session->base.session_signal);
 	return &session->base;
+
+error_ipc:
+	direct_ipc_finish(session->sock, session->child);
+	close(session->sock);
+error_session:
+	free(session);
+	return NULL;
 }
 
 const struct session_impl session_direct = {

session/logind.c

@@ -26,13 +26,9 @@ struct logind_session {
 
 	char *id;
 	char *path;
-	char *seat;
-
-	int drm_fd;
 };
 
-static int logind_take_device(struct wlr_session *restrict base,
-		const char *restrict path) {
+static int logind_take_device(struct wlr_session *base, const char *path) {
 	struct logind_session *session = wl_container_of(base, session, base);
 
 	int ret;
@@ -72,7 +68,7 @@ static int logind_take_device(struct wlr_session *restrict base,
 	}
 
 	if (major(st.st_rdev) == DRM_MAJOR) {
-		session->drm_fd = fd;
+		session->base.drm_fd = fd;
 	}
 
 error:
@@ -102,14 +98,14 @@ static void logind_release_device(struct wlr_session *base, int fd) {
 	}
 
 	if (major(st.st_rdev) == DRM_MAJOR) {
-		session->drm_fd = -1;
+		session->base.drm_fd = -1;
 	}
 
 	sd_bus_error_free(&error);
 	sd_bus_message_unref(msg);
 }
 
-static bool logind_change_vt(struct wlr_session *base, int vt) {
+static bool logind_change_vt(struct wlr_session *base, unsigned vt) {
 	struct logind_session *session = wl_container_of(base, session, base);
 
 	int ret;
@@ -187,7 +183,6 @@ static void logind_session_finish(struct wlr_session *base) {
 	sd_bus_unref(session->bus);
 	free(session->id);
 	free(session->path);
-	free(session->seat);
 	free(session);
 }
 
@@ -242,7 +237,7 @@ static int resume_device(sd_bus_message *msg, void *userdata, sd_bus_error *ret_
 	}
 
 	if (major == DRM_MAJOR) {
-		dup2(fd, session->drm_fd);
+		dup2(fd, session->base.drm_fd);
 		session->base.active = true;
 		wl_signal_emit(&session->base.session_signal, session);
 	}
@@ -305,11 +300,20 @@ static struct wlr_session *logind_session_start(struct wl_display *disp) {
 		goto error;
 	}
 
-	ret = sd_session_get_seat(session->id, &session->seat);
+	ret = sd_session_get_vt(session->id, &session->base.vtnr);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Session not running in virtual terminal");
+		goto error;
+	}
+
+	char *seat;
+	ret = sd_session_get_seat(session->id, &seat);
 	if (ret < 0) {
 		wlr_log(L_ERROR, "Failed to get seat id: %s", strerror(-ret));
 		goto error;
 	}
+	snprintf(session->base.seat, sizeof(session->base.seat), "%s", seat);
+	free(seat);
 
 	const char *fmt = "/org/freedesktop/login1/session/%s";
 	int len = snprintf(NULL, 0, fmt, session->id);
@@ -345,7 +349,7 @@ static struct wlr_session *logind_session_start(struct wl_display *disp) {
 
 	wlr_log(L_INFO, "Successfully loaded logind session");
 
-	session->drm_fd = -1;
+	session->base.drm_fd = -1;
 	session->base.impl = &session_logind;
 	session->base.active = true;
 	wl_signal_init(&session->base.session_signal);
@@ -357,7 +361,6 @@ error_bus:
 error:
 	free(session->path);
 	free(session->id);
-	free(session->seat);
 	return NULL;
 }
 

session/session.c

@@ -33,9 +33,7 @@ void wlr_session_finish(struct wlr_session *session) {
 	session->impl->finish(session);
 };
 
-int wlr_session_open_file(struct wlr_session *restrict session,
-	const char *restrict path) {
-
+int wlr_session_open_file(struct wlr_session *session, const char *path) {
 	return session->impl->open(session, path);
 }
 
@@ -43,6 +41,6 @@ void wlr_session_close_file(struct wlr_session *session, int fd) {
 	session->impl->close(session, fd);
 }
 
-bool wlr_session_change_vt(struct wlr_session *session, int vt) {
+bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
 	return session->impl->change_vt(session, vt);
 }