login: add new sd_session_get_type() and sd_session_get_class API calls

TODO

@@ -28,8 +28,6 @@ Features:
 
 * Possibly, detect whether SysV init scripts can do reloading by looking for "echo Usage:" lines
 
-* Add XDG_SESSION_CLASS
-
 * figure out whether we should leave dbus around during shutdown
 
 * support closing all fds via RLIMIT_NOFILE instead of /proc, in order to make chroot stuff work.

src/login/libsystemd-login.sym

@@ -39,3 +39,9 @@ global:
         sd_pid_get_unit;
         sd_session_get_service;
 } LIBSYSTEMD_LOGIN_31;
+
+LIBSYSTEMD_LOGIN_43 {
+global:
+        sd_session_get_type;
+        sd_session_get_class;
+} LIBSYSTEMD_LOGIN_38;

src/login/sd-login.c

@@ -433,18 +433,18 @@ _public_ int sd_session_get_uid(const char *session, uid_t *uid) {
         return r;
 }
 
-_public_ int sd_session_get_seat(const char *session, char **seat) {
+static int session_get_string(const char *session, const char *field, char **value) {
         char *p, *s = NULL;
         int r;
 
-        if (!seat)
+        if (!value)
                 return -EINVAL;
 
         r = file_of_session(session, &p);
         if (r < 0)
                 return r;
 
-        r = parse_env_file(p, NEWLINE, "SEAT", &s, NULL);
+        r = parse_env_file(p, NEWLINE, field, &s, NULL);
         free(p);
 
         if (r < 0) {
@@ -455,34 +455,24 @@ _public_ int sd_session_get_seat(const char *session, char **seat) {
         if (isempty(s))
                 return -ENOENT;
 
-        *seat = s;
+        *value = s;
         return 0;
 }
 
+_public_ int sd_session_get_seat(const char *session, char **seat) {
+        return session_get_string(session, "SEAT", seat);
+}
+
 _public_ int sd_session_get_service(const char *session, char **service) {
-        char *p, *s = NULL;
-        int r;
+        return session_get_string(session, "SERVICE", service);
+}
 
-        if (!service)
-                return -EINVAL;
+_public_ int sd_session_get_type(const char *session, char **type) {
+        return session_get_string(session, "TYPE", type);
+}
 
-        r = file_of_session(session, &p);
-        if (r < 0)
-                return r;
-
-        r = parse_env_file(p, NEWLINE, "SERVICE", &s, NULL);
-        free(p);
-
-        if (r < 0) {
-                free(s);
-                return r;
-        }
-
-        if (isempty(s))
-                return -ENOENT;
-
-        *service = s;
-        return 0;
+_public_ int sd_session_get_class(const char *session, char **class) {
+        return session_get_string(session, "CLASS", class);
 }
 
 static int file_of_seat(const char *seat, char **_p) {

src/login/test-login.c

@@ -30,7 +30,7 @@
 int main(int argc, char* argv[]) {
         int r, k;
         uid_t u, u2;
-        char *seat;
+        char *seat, *type, *class;
         char *session;
         char *state;
         char *session2;
@@ -75,6 +75,14 @@ int main(int argc, char* argv[]) {
         printf("uid = %lu\n", (unsigned long) u);
         assert_se(u == u2);
 
+        assert_se(sd_session_get_type(session, &type) >= 0);
+        printf("type = %s\n", type);
+        free(type);
+
+        assert_se(sd_session_get_class(session, &class) >= 0);
+        printf("class = %s\n", class);
+        free(class);
+
         assert_se(sd_session_get_seat(session, &seat) >= 0);
         printf("seat = %s\n", seat);
 
@@ -125,13 +133,13 @@ int main(int argc, char* argv[]) {
         printf("seats = %s\n", t);
         free(t);
 
+        assert_se(sd_get_seats(NULL) == r);
+
         r = sd_seat_get_active(NULL, &t, NULL);
         assert_se(r >= 0);
         printf("active session on current seat = %s\n", t);
         free(t);
 
-        assert_se(sd_get_seats(NULL) == r);
-
         r = sd_get_sessions(&sessions);
         assert_se(r >= 0);
         assert_se(r == (int) strv_length(sessions));

src/systemd/sd-login.h

@@ -90,6 +90,12 @@ int sd_session_get_seat(const char *session, char **seat);
 /* Determine the (PAM) service name this session was registered by. */
 int sd_session_get_service(const char *session, char **service);
 
+/* Determine the type of this session, i.e. one of "tty", "x11" or "unspecified". */
+int sd_session_get_type(const char *session, char **type);
+
+/* Determine the class of this session, i.e. one of "user", "greeter" or "lock-screen". */
+int sd_session_get_class(const char *session, char **class);
+
 /* Return active session and user of seat */
 int sd_seat_get_active(const char *seat, char **session, uid_t *uid);