New session interface.

CMakeLists.txt

@@ -51,8 +51,7 @@ find_package(DRM REQUIRED)
 find_package(GBM REQUIRED)
 find_package(LibInput REQUIRED)
 find_package(Udev REQUIRED)
-find_package(Dbus)
-find_package(Systemd REQUIRED)
+find_package(Systemd)
 
 include(Wayland)
 include(Manpage)
@@ -62,5 +61,6 @@ include_directories(include)
 add_subdirectory(backend)
 add_subdirectory(common)
 add_subdirectory(wayland)
+add_subdirectory(session)
 
 add_subdirectory(example)

include/session/interface.h

@@ -0,0 +1,20 @@
+#ifndef WLR_SESSION_INTERFACE_H
+#define WLR_SESSION_INTERFACE_H
+
+struct wlr_session;
+
+struct session_interface {
+	struct wlr_session *(*start)(void);
+	void (*finish)(struct wlr_session *session);
+	int (*open)(struct wlr_session *restrict session,
+		const char *restrict path);
+	void (*close)(struct wlr_session *session, int fd);
+};
+
+struct wlr_session {
+	struct session_interface iface;
+};
+
+extern const struct session_interface session_logind_iface;
+
+#endif

include/wlr/session.h

@@ -0,0 +1,12 @@
+#ifndef WLR_SESSION_H
+#define WLR_SESSION_H
+
+struct wlr_session;
+
+struct wlr_session *wlr_session_start(void);
+void wlr_session_finish(struct wlr_session *session);
+int wlr_session_open_file(struct wlr_session *restrict session,
+	const char *restrict path);
+void wlr_session_close_file(struct wlr_session *session, int fd);
+
+#endif

session/CMakeLists.txt

@@ -0,0 +1,24 @@
+include_directories(
+	${WAYLAND_INCLUDE_DIR}
+)
+
+set(sources
+    session.c
+)
+
+set(libs
+    wlr-common
+    ${WAYLAND_LIBRARIES}
+)
+
+if (SYSTEMD_FOUND)
+    add_definitions(${SYSTEMD_DEFINITIONS})
+    include_directories(${SYSTEMD_INCLUDE_DIRS})
+
+    add_definitions(-DHAS_SYSTEMD)
+    list(APPEND sources logind.c)
+    list(APPEND libs ${SYSTEMD_LIBRARIES})
+endif ()
+
+add_library(wlr-session ${sources})
+target_link_libraries(wlr-session ${libs})

session/logind.c

@@ -0,0 +1,220 @@
+#define _POSIX_C_SOURCE 200809L
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <systemd/sd-bus.h>
+#include <systemd/sd-login.h>
+#include <unistd.h>
+#include <sys/sysmacros.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <wayland-server.h>
+
+#include "session/interface.h"
+#include "common/log.h"
+
+struct logind_session {
+	struct wlr_session base;
+
+	sd_bus *bus;
+
+	char *id;
+	char *path;
+	char *seat;
+};
+
+static int logind_take_device(struct wlr_session *restrict base,
+	const char *restrict path) {
+
+	struct logind_session *session = wl_container_of(base, session, base);
+
+	int ret;
+	int fd = -1;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	struct stat st;
+	if (stat(path, &st) < 0) {
+		wlr_log(L_ERROR, "Failed to stat '%s'", path);
+		return -1;
+	}
+
+	ret = sd_bus_call_method(session->bus, "org.freedesktop.login1",
+		session->path, "org.freedesktop.login1.Session", "TakeDevice",
+		&error, &msg, "uu", major(st.st_rdev), minor(st.st_rdev));
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to take device '%s': %s", path, error.message);
+		goto error;
+	}
+
+	int paused = 0;
+	ret = sd_bus_message_read(msg, "hb", &fd, &paused);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to parse DBus response for '%s': %s",
+			path, strerror(-ret));
+		goto error;
+	}
+
+	// The original fd seem to be closed when the message is freed
+	// so we just clone it.
+	fd = fcntl(fd, F_DUPFD_CLOEXEC, 0);
+	if (fd == -1) {
+		wlr_log(L_ERROR, "Failed to clone file descriptor for '%s': %s",
+			path, strerror(errno));
+		goto error;
+	}
+
+error:
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return fd;
+}
+
+static void logind_release_device(struct wlr_session *base, int fd) {
+	struct logind_session *session = wl_container_of(base, session, base);
+
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	struct stat st;
+	if (fstat(fd, &st) < 0) {
+		wlr_log(L_ERROR, "Failed to stat device '%d'", fd);
+		return;
+	}
+
+	ret = sd_bus_call_method(session->bus, "org.freedesktop.login1",
+		session->path, "org.freedesktop.login1.Session", "ReleaseDevice",
+		&error, &msg, "uu", major(st.st_rdev), minor(st.st_rdev));
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to release device '%d'", fd);
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+}
+
+static bool session_activate(struct logind_session *session) {
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	ret = sd_bus_call_method(session->bus, "org.freedesktop.login1",
+		session->path, "org.freedesktop.login1.Session", "Activate",
+		&error, &msg, "");
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to activate session");
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return ret >= 0;
+}
+
+static bool take_control(struct logind_session *session) {
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	ret = sd_bus_call_method(session->bus, "org.freedesktop.login1",
+		session->path, "org.freedesktop.login1.Session", "TakeControl",
+		&error, &msg, "b", false);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to take control of session");
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return ret >= 0;
+}
+
+static void release_control(struct logind_session *session) {
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+
+	ret = sd_bus_call_method(session->bus, "org.freedesktop.login1",
+		session->path, "org.freedesktop.login1.Session", "ReleaseControl",
+		&error, &msg, "");
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to release control of session");
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+}
+
+static void logind_session_finish(struct wlr_session *base) {
+	struct logind_session *session = wl_container_of(base, session, base);
+
+	release_control(session);
+
+	sd_bus_unref(session->bus);
+	free(session->id);
+	free(session->path);
+	free(session->seat);
+	free(session);
+}
+
+static struct wlr_session *logind_session_start(void) {
+	int ret;
+	struct logind_session *session = calloc(1, sizeof(*session));
+	if (!session) {
+		wlr_log(L_ERROR, "Allocation failed: %s", strerror(errno));
+		return NULL;
+	}
+
+	ret = sd_pid_get_session(getpid(), &session->id);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to get session id: %s", strerror(-ret));
+		goto error;
+	}
+
+	ret = sd_session_get_seat(session->id, &session->seat);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to get seat id: %s", strerror(-ret));
+		goto error;
+	}
+
+	const char *fmt = "/org/freedesktop/login1/session/%s";
+	int len = snprintf(NULL, 0, fmt, session->id);
+
+	session->path = malloc(len + 1);
+	if (!session->path)
+		goto error;
+
+	sprintf(session->path, fmt, session->id);
+
+	ret = sd_bus_default_system(&session->bus);
+	if (ret < 0) {
+		wlr_log(L_ERROR, "Failed to open DBus connection: %s", strerror(-ret));
+		goto error;
+	}
+
+	if (!session_activate(session))
+		goto error_bus;
+
+	if (!take_control(session))
+		goto error_bus;
+
+	return &session->base;
+
+error_bus:
+	sd_bus_unref(session->bus);
+
+error:
+	free(session->path);
+	free(session->id);
+	free(session->seat);
+	return NULL;
+}
+
+const struct session_interface session_logind_iface = {
+	.start = logind_session_start,
+	.finish = logind_session_finish,
+	.open = logind_take_device,
+	.close = logind_release_device,
+};

session/session.c

@@ -0,0 +1,38 @@
+#include <stddef.h>
+
+#include <wlr/session.h>
+#include "session/interface.h"
+
+static const struct session_interface *ifaces[] = {
+#ifdef HAS_SYSTEMD
+	&session_logind_iface,
+#endif
+	NULL,
+};
+
+struct wlr_session *wlr_session_start(void) {
+	const struct session_interface **iter;
+
+	for (iter = ifaces; *iter; ++iter) {
+		struct wlr_session *session = (*iter)->start();
+		if (session) {
+			return session;
+		}
+	}
+
+	return NULL;
+}
+
+void wlr_session_finish(struct wlr_session *session) {
+	session->iface.finish(session);
+};
+
+int wlr_session_open_file(struct wlr_session *restrict session,
+	const char *restrict path) {
+
+	return session->iface.open(session, path);
+}
+
+void wlr_session_close_file(struct wlr_session *session, int fd) {
+	session->iface.close(session, fd);
+}