sd-login: if NULL or 0 is passed as first parameter of the sd_xxx functions, work on objects of the calling process

5 files changed, 92 insertions, 38 deletions

diff --git a/man/sd_pid_get_session.xml b/man/sd_pid_get_session.xml
index bd9580462..94f533022 100644
--- a/man/sd_pid_get_session.xml
+++ b/man/sd_pid_get_session.xml
@@ -113,6 +113,10 @@
                 fail. For processes not being part of a login session
                 and not being a shared process of a user this function
                 will fail.</para>
+
+                <para>If the <literal>pid</literal> paramater of any
+                of these functions is passed as 0 the operation is
+                executed for the calling process.</para>
         </refsect1>
 
         <refsect1>
diff --git a/man/sd_seat_get_active.xml b/man/sd_seat_get_active.xml
index 14cda60a5..acc6ee4ea 100644
--- a/man/sd_seat_get_active.xml
+++ b/man/sd_seat_get_active.xml
@@ -70,7 +70,7 @@
 
                         <funcprototype>
                                 <funcdef>int <function>sd_seat_can_multi_session</function></funcdef>
-                                <paramdef>const char* <parameter>session</parameter></paramdef>
+                                <paramdef>const char* <parameter>seat</parameter></paramdef>
                         </funcprototype>
                 </funcsynopsis>
         </refsynopsisdiv>
@@ -110,6 +110,11 @@
                 capable of multi-session, i.e. allows multiple login
                 sessions in parallel (whith only one being active at a
                 time).</para>
+
+                <para>If the <literal>seat</literal> parameter of any
+                of these functions is passed as NULL the operation is
+                executed for the seat of the session of the calling
+                process, if there is any.</para>
         </refsect1>
 
         <refsect1>
diff --git a/man/sd_session_is_active.xml b/man/sd_session_is_active.xml
index 516275ea9..5db305d46 100644
--- a/man/sd_session_is_active.xml
+++ b/man/sd_session_is_active.xml
@@ -110,6 +110,11 @@
                 the libc
                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                 call after use.</para>
+
+                <para>If the <literal>session</literal> parameter of
+                any of these functions is passed as NULL the operation
+                is executed for the session the calling process is a
+                member of, if there is any.</para>
         </refsect1>
 
         <refsect1>
diff --git a/src/login/sd-login.c b/src/login/sd-login.c
index eb1a4b910..5a03d614b 100644
--- a/src/login/sd-login.c
+++ b/src/login/sd-login.c
@@ -354,17 +354,40 @@ _public_ int sd_uid_get_seats(uid_t uid, int require_active, char ***seats) {
         return uid_get_array(uid, require_active ? "ACTIVE_SEATS" : "SEATS", seats);
 }
 
-_public_ int sd_session_is_active(const char *session) {
+static int file_of_session(const char *session, char **_p) {
+        char *p;
         int r;
-        char *p, *s = NULL;
 
-        if (!session)
-                return -EINVAL;
+        assert(_p);
+
+        if (session)
+                p = strappend("/run/systemd/sessions/", session);
+        else {
+                char *buf;
+
+                r = sd_pid_get_session(0, &buf);
+                if (r < 0)
+                        return r;
+
+                p = strappend("/run/systemd/sessions/", buf);
+                free(buf);
+        }
 
-        p = strappend("/run/systemd/sessions/", session);
         if (!p)
                 return -ENOMEM;
 
+        *_p = p;
+        return 0;
+}
+
+_public_ int sd_session_is_active(const char *session) {
+        int r;
+        char *p, *s = NULL;
+
+        r = file_of_session(session, &p);
+        if (r < 0)
+                return r;
+
         r = parse_env_file(p, NEWLINE, "ACTIVE", &s, NULL);
         free(p);
 
@@ -386,14 +409,12 @@ _public_ int sd_session_get_uid(const char *session, uid_t *uid) {
         int r;
         char *p, *s = NULL;
 
-        if (!session)
-                return -EINVAL;
         if (!uid)
                 return -EINVAL;
 
-        p = strappend("/run/systemd/sessions/", session);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_session(session, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE, "UID", &s, NULL);
         free(p);
@@ -416,14 +437,12 @@ _public_ int sd_session_get_seat(const char *session, char **seat) {
         char *p, *s = NULL;
         int r;
 
-        if (!session)
-                return -EINVAL;
         if (!seat)
                 return -EINVAL;
 
-        p = strappend("/run/systemd/sessions/", session);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_session(session, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE, "SEAT", &s, NULL);
         free(p);
@@ -444,14 +463,12 @@ _public_ int sd_session_get_service(const char *session, char **service) {
         char *p, *s = NULL;
         int r;
 
-        if (!session)
-                return -EINVAL;
         if (!service)
                 return -EINVAL;
 
-        p = strappend("/run/systemd/sessions/", session);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_session(session, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE, "SERVICE", &s, NULL);
         free(p);
@@ -468,18 +485,42 @@ _public_ int sd_session_get_service(const char *session, char **service) {
         return 0;
 }
 
+static int file_of_seat(const char *seat, char **_p) {
+        char *p;
+        int r;
+
+        assert(_p);
+
+        if (seat)
+                p = strappend("/run/systemd/seats/", seat);
+        else {
+                char *buf;
+
+                r = sd_session_get_seat(NULL, &buf);
+                if (r < 0)
+                        return r;
+
+                p = strappend("/run/systemd/seats/", buf);
+                free(buf);
+        }
+
+        if (!p)
+                return -ENOMEM;
+
+        *_p = p;
+        return 0;
+}
+
 _public_ int sd_seat_get_active(const char *seat, char **session, uid_t *uid) {
         char *p, *s = NULL, *t = NULL;
         int r;
 
-        if (!seat)
-                return -EINVAL;
         if (!session && !uid)
                 return -EINVAL;
 
-        p = strappend("/run/systemd/seats/", seat);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_seat(seat, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE,
                            "ACTIVE", &s,
@@ -528,12 +569,9 @@ _public_ int sd_seat_get_sessions(const char *seat, char ***sessions, uid_t **ui
         unsigned n = 0;
         int r;
 
-        if (!seat)
-                return -EINVAL;
-
-        p = strappend("/run/systemd/seats/", seat);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_seat(seat, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE,
                            "SESSIONS", &s,
@@ -619,12 +657,9 @@ _public_ int sd_seat_can_multi_session(const char *seat) {
         char *p, *s = NULL;
         int r;
 
-        if (!seat)
-                return -EINVAL;
-
-        p = strappend("/run/systemd/seats/", seat);
-        if (!p)
-                return -ENOMEM;
+        r = file_of_seat(seat, &p);
+        if (r < 0)
+                return r;
 
         r = parse_env_file(p, NEWLINE,
                            "CAN_MULTI_SESSION", &s,
diff --git a/src/login/test-login.c b/src/login/test-login.c
index ae041b6a5..459672106 100644
--- a/src/login/test-login.c
+++ b/src/login/test-login.c
@@ -125,6 +125,11 @@ int main(int argc, char* argv[]) {
         printf("seats = %s\n", t);
         free(t);
 
+        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);