Added direct session support

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 REQUIRED)
 find_package(Systemd)
 
 include(Wayland)

session/CMakeLists.txt

@@ -1,5 +1,7 @@
 include_directories(
     ${WAYLAND_INCLUDE_DIR}
+    ${DRM_INCLUDE_DIRS}
+    ${Libcap_INCLUDE_DIRS}
 )
 
 set(sources
@@ -10,6 +12,7 @@ set(sources
 set(libs
     wlr-util
     ${WAYLAND_LIBRARIES}
+    ${Libcap_LIBRARIES}
 )
 
 if (SYSTEMD_FOUND)

session/direct.c

@@ -5,36 +5,174 @@
 #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 <sys/capability.h>
+#include <linux/kd.h>
+#include <linux/major.h>
+#include <linux/vt.h>
 #include <wayland-server.h>
+#include <xf86drm.h>
 #include <wlr/session/interface.h>
 #include <wlr/util/log.h>
 
+#ifndef KDSKBMUTE
+#define KDSKBMUTE	0x4B51
+#endif
+
+enum { DRM_MAJOR = 226 };
+
 const struct session_impl session_direct;
 
 struct direct_session {
 	struct wlr_session base;
+	int tty_fd;
+	int drm_fd;
+	int kb_mode;
+
+	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);
+	struct direct_session *session = wl_container_of(base, session, base);
+	int fd = open(path, O_RDWR | O_CLOEXEC | O_NOCTTY | O_NONBLOCK);
+	if (fd == -1) {
+		wlr_log_errno(L_ERROR, "%s", path);
+		return -errno;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st) == 0 && major(st.st_rdev) == DRM_MAJOR) {
+		session->drm_fd = fd;
+		drmSetMaster(fd);
+	}
+
+	return fd;
 }
 
 static void direct_session_close(struct wlr_session *base, int fd) {
+	struct direct_session *session = wl_container_of(base, session, base);
+
+	if (fd == session->drm_fd) {
+		drmDropMaster(fd);
+		session->drm_fd = -1;
+	}
+
 	close(fd);
 }
 
 static bool direct_change_vt(struct wlr_session *base, int vt) {
-	// TODO
-	return false;
+	struct direct_session *session = wl_container_of(base, session, base);
+	return ioctl(session->tty_fd, VT_ACTIVATE, 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,
+	};
 
+	if (ioctl(session->tty_fd, KDSKBMUTE, 0)) {
+		ioctl(session->tty_fd, KDSKBMODE, session->kb_mode);
+	}
+	ioctl(session->tty_fd, KDSETMODE, KD_TEXT);
+	ioctl(session->tty_fd, VT_SETMODE, &mode);
+
+	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);
+		drmDropMaster(session->drm_fd);
+		ioctl(session->tty_fd, VT_RELDISP, 1);
+	} else {
+		ioctl(session->tty_fd, VT_RELDISP, VT_ACKACQ);
+		drmSetMaster(session->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) {
+	session->tty_fd = dup(STDIN_FILENO);
+
+	struct stat st;
+	if (fstat(session->tty_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 ret;
+
+	int kd_mode;
+	ret = ioctl(session->tty_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(session->tty_fd, VT_ACTIVATE, minor(st.st_rdev));
+	ioctl(session->tty_fd, VT_WAITACTIVE, minor(st.st_rdev));
+
+	if (ioctl(session->tty_fd, KDGKBMODE, &session->kb_mode)) {
+		wlr_log_errno(L_ERROR, "Failed to read keyboard mode");
+		goto error;
+	}
+
+	if (ioctl(session->tty_fd, KDSKBMUTE, 1) &&
+			ioctl(session->tty_fd, KDSKBMODE, K_OFF)) {
+		wlr_log_errno(L_ERROR, "Failed to set keyboard mode");
+		goto error;
+	}
+
+	if (ioctl(session->tty_fd, KDSETMODE, KD_GRAPHICS)) {
+		wlr_log_errno(L_ERROR, "Failed to get graphics mode on tty");
+		goto error;
+	}
+
+	struct vt_mode mode = {
+		.mode = VT_PROCESS,
+		.relsig = SIGUSR1,
+		.acqsig = SIGUSR1,
+	};
+
+	if (ioctl(session->tty_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;
+	}
+
+	return true;
+
+error:
+	close(session->tty_fd);
+	return false;
+}
+
 static struct wlr_session *direct_session_start(struct wl_display *disp) {
 	struct direct_session *session = calloc(1, sizeof(*session));
 	if (!session) {
@@ -42,12 +180,31 @@ static struct wlr_session *direct_session_start(struct wl_display *disp) {
 		return NULL;
 	}
 
+	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);
+		goto error_session;
+	}
+
+	cap_free(cap);
+
+	if (!setup_tty(session, disp)) {
+		goto error_session;
+	}
+
 	wlr_log(L_INFO, "Successfully loaded direct session");
 
 	session->base.impl = &session_direct;
 	session->base.active = true;
 	wl_signal_init(&session->base.session_signal);
 	return &session->base;
+
+error_session:
+	free(session);
+	return NULL;
 }
 
 const struct session_impl session_direct = {