Inital commit of libotd.

1 files changed, 224 insertions, 0 deletions

diff --git a/backend/drm/session.c b/backend/drm/session.c
new file mode 100644
index 00000000..c845fb27
--- /dev/null
+++ b/backend/drm/session.c
@@ -0,0 +1,224 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.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 "session.h"
+#include "otd.h"
+
+int take_device(struct otd *restrict otd,
+		       const char *restrict path,
+		       bool *restrict paused_out)
+{
+	int ret;
+	int fd = -1;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+	struct otd_session *s = &otd->session;
+
+	struct stat st;
+	if (stat(path, &st) < 0) {
+		fprintf(stderr, "Failed to stat '%s'\n", path);
+		return -1;
+	}
+
+	ret = sd_bus_call_method(s->bus,
+				 "org.freedesktop.login1",
+				 s->path,
+				 "org.freedesktop.login1.Session",
+				 "TakeDevice",
+				 &error, &msg,
+				 "uu", major(st.st_rdev), minor(st.st_rdev));
+	if (ret < 0) {
+		fprintf(stderr, "%s\n", error.message);
+		goto error;
+	}
+
+	int paused = 0;
+	ret = sd_bus_message_read(msg, "hb", &fd, &paused);
+	if (ret < 0) {
+		fprintf(stderr, "%s\n", 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 (paused_out)
+		*paused_out = paused;
+
+error:
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return fd;
+}
+
+void release_device(struct otd *otd, int fd)
+{
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+	struct otd_session *s = &otd->session;
+
+	struct stat st;
+	if (fstat(fd, &st) < 0) {
+		fprintf(stderr, "Could not stat fd %d\n", fd);
+		return;
+	}
+
+	ret = sd_bus_call_method(s->bus,
+				 "org.freedesktop.login1",
+				 s->path,
+				 "org.freedesktop.login1.Session",
+				 "ReleaseDevice",
+				 &error, &msg,
+				 "uu", major(st.st_rdev), minor(st.st_rdev));
+	if (ret < 0) {
+		/* Log something */;
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+}
+
+static bool session_activate(struct otd *otd)
+{
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+	struct otd_session *s = &otd->session;
+
+	ret = sd_bus_call_method(s->bus,
+				 "org.freedesktop.login1",
+				 s->path,
+				 "org.freedesktop.login1.Session",
+				 "Activate",
+				 &error, &msg,
+				 "");
+	if (ret < 0) {
+		fprintf(stderr, "%s\n", error.message);
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return ret >= 0;
+}
+
+static bool take_control(struct otd *otd)
+{
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+	struct otd_session *s = &otd->session;
+
+	ret = sd_bus_call_method(s->bus,
+				 "org.freedesktop.login1",
+				 s->path,
+				 "org.freedesktop.login1.Session",
+				 "TakeControl",
+				 &error, &msg,
+				 "b", false);
+	if (ret < 0) {
+		/* Log something */;
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+	return ret >= 0;
+}
+
+static void release_control(struct otd *otd)
+{
+	int ret;
+	sd_bus_message *msg = NULL;
+	sd_bus_error error = SD_BUS_ERROR_NULL;
+	struct otd_session *s = &otd->session;
+
+	ret = sd_bus_call_method(s->bus,
+				 "org.freedesktop.login1",
+				 s->path,
+				 "org.freedesktop.login1.Session",
+				 "ReleaseControl",
+				 &error, &msg,
+				 "");
+	if (ret < 0) {
+		/* Log something */;
+	}
+
+	sd_bus_error_free(&error);
+	sd_bus_message_unref(msg);
+}
+
+void otd_close_session(struct otd *otd)
+{
+	release_device(otd, otd->fd);
+	release_control(otd);
+
+	sd_bus_unref(otd->session.bus);
+	free(otd->session.id);
+	free(otd->session.path);
+	free(otd->session.seat);
+}
+
+bool otd_new_session(struct otd *otd)
+{
+	int ret;
+	struct otd_session *s = &otd->session;
+
+	ret = sd_pid_get_session(getpid(), &s->id);
+	if (ret < 0) {
+		fprintf(stderr, "Could not get session\n");
+		goto error;
+	}
+
+	ret = sd_session_get_seat(s->id, &s->seat);
+	if (ret < 0) {
+		fprintf(stderr, "Could not get seat\n");
+		goto error;
+	}
+
+	// This could be done using asprintf, but I don't want to define _GNU_SOURCE
+
+	const char *fmt = "/org/freedesktop/login1/session/%s";
+	int len = snprintf(NULL, 0, fmt, s->id);
+
+	s->path = malloc(len + 1);
+	if (!s->path)
+		goto error;
+
+	sprintf(s->path, fmt, s->id);
+
+	ret = sd_bus_open_system(&s->bus);
+	if (ret < 0) {
+		fprintf(stderr, "Could not open bus\n");
+		goto error;
+	}
+
+	if (!session_activate(otd)) {
+		fprintf(stderr, "Could not activate session\n");
+		goto error_bus;
+	}
+
+	if (!take_control(otd)) {
+		fprintf(stderr, "Could not take control of session\n");
+		goto error_bus;
+	}
+
+	return true;
+
+error_bus:
+	sd_bus_unref(s->bus);
+
+error:
+	free(s->path);
+	free(s->id);
+	free(s->seat);
+	return false;
+}