login: add public sd_session_get_desktop() API

The desktop brand is stored as DESKTOP variable for sessions. It can be
set arbitrarily by the session owner and identifies the desktop
environment that is running on that session.

5 files changed, 54 insertions, 2 deletions

diff --git a/man/pam_systemd.xml b/man/pam_systemd.xml
index 52dfe9df43..4df26a3f2b 100644
--- a/man/pam_systemd.xml
+++ b/man/pam_systemd.xml
@@ -268,7 +268,9 @@
                                 as defined by the <ulink
                                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">Desktop
                                 Entry
-                                Specification</ulink>.</para></listitem>
+                                Specification</ulink>. See
+                                <citerefentry><refentrytitle>sd_session_get_desktop</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                                for more details.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
diff --git a/man/sd_session_is_active.xml b/man/sd_session_is_active.xml
index 5006be4df5..e9840669c2 100644
--- a/man/sd_session_is_active.xml
+++ b/man/sd_session_is_active.xml
@@ -51,6 +51,7 @@
                 <refname>sd_session_get_service</refname>
                 <refname>sd_session_get_type</refname>
                 <refname>sd_session_get_class</refname>
+                <refname>sd_session_get_desktop</refname>
                 <refname>sd_session_get_display</refname>
                 <refname>sd_session_get_tty</refname>
                 <refname>sd_session_get_vt</refname>
@@ -110,6 +111,12 @@
                         </funcprototype>
 
                         <funcprototype>
+                                <funcdef>int <function>sd_session_get_desktop</function></funcdef>
+                                <paramdef>const char *<parameter>session</parameter></paramdef>
+                                <paramdef>char **<parameter>desktop</parameter></paramdef>
+                        </funcprototype>
+
+                        <funcprototype>
                                 <funcdef>int <function>sd_session_get_display</function></funcdef>
                                 <paramdef>const char *<parameter>session</parameter></paramdef>
                                 <paramdef>char **<parameter>display</parameter></paramdef>
@@ -218,6 +225,22 @@
                 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                 call after use.</para>
 
+                <para><function>sd_session_get_desktop()</function> may
+                be used to determine the brand of the desktop running on
+                the session identified by the specified session identifier.
+                This field can be set freely by desktop environments and
+                does not follow any special formatting. However, desktops
+                are strongly recommended to use the same identifiers and
+                capitalization as for
+                <varname>$XDG_CURRENT_DESKTOP</varname>, as defined by
+                the <ulink
+                url="http://standards.freedesktop.org/desktop-entry-spec/latest/">Desktop
+                Entry
+                Specification</ulink>. The returned string needs to be
+                freed with the libc
+                <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                call after use.</para>
+
                 <para><function>sd_session_get_display()</function>
                 may be used to determine the X11 display of the
                 session identified by the specified session
diff --git a/src/libsystemd/libsystemd.sym.m4 b/src/libsystemd/libsystemd.sym.m4
index d1450fbb26..87da7ac021 100644
--- a/src/libsystemd/libsystemd.sym.m4
+++ b/src/libsystemd/libsystemd.sym.m4
@@ -153,6 +153,11 @@ global:
         sd_machine_get_ifindices;
 } LIBSYSTEMD_214;
 
+LIBSYSTEMD_217 {
+global:
+        sd_session_get_desktop;
+} LIBSYSTEMD_216;
+
 m4_ifdef(`ENABLE_KDBUS',
 LIBSYSTEMD_FUTURE {
 global:
@@ -438,5 +443,5 @@ global:
         /* sd-path */
         sd_path_home;
         sd_path_search;
-} LIBSYSTEMD_216;
+} LIBSYSTEMD_217;
 )
diff --git a/src/libsystemd/sd-login/sd-login.c b/src/libsystemd/sd-login/sd-login.c
index 95cb6ff581..c72d23ed53 100644
--- a/src/libsystemd/sd-login/sd-login.c
+++ b/src/libsystemd/sd-login/sd-login.c
@@ -485,6 +485,25 @@ _public_ int sd_session_get_class(const char *session, char **class) {
         return session_get_string(session, "CLASS", class);
 }
 
+_public_ int sd_session_get_desktop(const char *session, char **desktop) {
+        _cleanup_free_ char *escaped = NULL;
+        char *t;
+        int r;
+
+        assert_return(desktop, -EINVAL);
+
+        r = session_get_string(session, "DESKTOP", &escaped);
+        if (r < 0)
+                return r;
+
+        t = cunescape(escaped);
+        if (!t)
+                return -ENOMEM;
+
+        *desktop = t;
+        return 0;
+}
+
 _public_ int sd_session_get_display(const char *session, char **display) {
         return session_get_string(session, "DISPLAY", display);
 }
diff --git a/src/systemd/sd-login.h b/src/systemd/sd-login.h
index 1eb3be30b5..93af19709b 100644
--- a/src/systemd/sd-login.h
+++ b/src/systemd/sd-login.h
@@ -147,6 +147,9 @@ 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 **clazz);
 
+/* Determine the desktop brand of this session, i.e. something like "GNOME", "KDE" or "SYSTEMD-CONSOLE". */
+int sd_session_get_desktop(const char *session, char **desktop);
+
 /* Determine the X11 display of this session. */
 int sd_session_get_display(const char *session, char **display);