login: implement sd_session_get_service()

4 files changed, 52 insertions, 2 deletions

diff --git a/man/sd_session_is_active.xml b/man/sd_session_is_active.xml
index 88b22fd9f8..516275ea9f 100644
--- a/man/sd_session_is_active.xml
+++ b/man/sd_session_is_active.xml
@@ -46,6 +46,7 @@
                 <refname>sd_session_is_active</refname>
                 <refname>sd_session_get_uid</refname>
                 <refname>sd_session_get_seat</refname>
+                <refname>sd_session_get_service</refname>
                 <refpurpose>Determine state of a specific session</refpurpose>
         </refnamediv>
 
@@ -69,6 +70,12 @@
                                 <paramdef>const char* <parameter>session</parameter></paramdef>
                                 <paramdef>char** <parameter>seat</parameter></paramdef>
                         </funcprototype>
+
+                        <funcprototype>
+                                <funcdef>int <function>sd_session_get_service</function></funcdef>
+                                <paramdef>const char* <parameter>session</parameter></paramdef>
+                                <paramdef>char** <parameter>service</parameter></paramdef>
+                        </funcprototype>
                 </funcsynopsis>
         </refsynopsisdiv>
 
@@ -94,6 +101,15 @@
                 returned string needs to be freed with the libc
                 <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                 call after use.</para>
+
+                <para><function>sd_session_get_service()</function>
+                may be used to determine the name of the service (as
+                passed during PAM session setup) that registered the
+                session identified by the specified session
+                identifier. The returned string needs to be freed with
+                the libc
+                <citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                call after use.</para>
         </refsect1>
 
         <refsect1>
@@ -102,7 +118,8 @@
                 <para>If the test succeeds
                 <function>sd_session_is_active()</function> returns a
                 positive integer, if it fails 0.  On success
-                <function>sd_session_get_uid()</function> and
+                <function>sd_session_get_uid()</function>,
+                <function>sd_session_get_service()</function> and
                 <function>sd_session_get_seat()</function> return 0 or
                 a positive integer. On failure, these calls return a
                 negative errno-style error code.</para>
@@ -112,7 +129,8 @@
                 <title>Notes</title>
 
                 <para>The <function>sd_session_is_active()</function>,
-                <function>sd_session_get_uid()</function>, and
+                <function>sd_session_get_uid()</function>,
+                <function>sd_session_get_service()</function> and
                 <function>sd_session_get_seat()</function> interfaces
                 are available as shared library, which can be compiled
                 and linked to with the
diff --git a/src/login/libsystemd-login.sym b/src/login/libsystemd-login.sym
index 15e505e83b..3100c17662 100644
--- a/src/login/libsystemd-login.sym
+++ b/src/login/libsystemd-login.sym
@@ -37,4 +37,5 @@ local:
 LIBSYSTEMD_LOGIN_38 {
 global:
         sd_pid_get_unit;
+        sd_session_get_service;
 } LIBSYSTEMD_LOGIN_31;
diff --git a/src/login/sd-login.c b/src/login/sd-login.c
index 8893b1de80..ed98412266 100644
--- a/src/login/sd-login.c
+++ b/src/login/sd-login.c
@@ -415,6 +415,34 @@ _public_ int sd_session_get_seat(const char *session, char **seat) {
         return 0;
 }
 
+_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 = 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_seat_get_active(const char *seat, char **session, uid_t *uid) {
         char *p, *s = NULL, *t = NULL;
         int r;
diff --git a/src/systemd/sd-login.h b/src/systemd/sd-login.h
index 00de6716b0..7d76f9a44e 100644
--- a/src/systemd/sd-login.h
+++ b/src/systemd/sd-login.h
@@ -83,6 +83,9 @@ int sd_session_get_uid(const char *session, uid_t *uid);
 /* Determine seat of session */
 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);
+
 /* Return active session and user of seat */
 int sd_seat_get_active(const char *seat, char **session, uid_t *uid);