login: add sd_login_monitor_get_timeout() public api call

We don't need this right now, but we should keep our options open, in
case we need more than just an fd for waking up.

4 files changed, 38 insertions, 4 deletions

diff --git a/src/login/libsystemd-login.sym b/src/login/libsystemd-login.sym
index 55a828773b..ce2304a1ba 100644
--- a/src/login/libsystemd-login.sym
+++ b/src/login/libsystemd-login.sym
@@ -62,4 +62,5 @@ global:
 LIBSYSTEMD_LOGIN_201 {
 global:
         sd_login_monitor_get_events;
+        sd_login_monitor_get_timeout;
 } LIBSYSTEMD_LOGIN_198;
diff --git a/src/login/sd-login.c b/src/login/sd-login.c
index 861a57166d..7513f76cb3 100644
--- a/src/login/sd-login.c
+++ b/src/login/sd-login.c
@@ -804,5 +804,23 @@ _public_ int sd_login_monitor_get_events(sd_login_monitor *m) {
         if (!m)
                 return -EINVAL;
 
+        /* For now we will only return POLLIN here, since we don't
+         * need anything else ever for inotify.  However, let's have
+         * this API to keep our options open should we later on need
+         * it. */
         return POLLIN;
 }
+
+_public_ int sd_login_monitor_get_timeout(sd_login_monitor *m, uint64_t *timeout_usec) {
+
+        if (!m)
+                return -EINVAL;
+        if (!timeout_usec)
+                return -EINVAL;
+
+        /* For now we will only return (uint64_t) -1, since we don't
+         * need any timeout. However, let's have this API to keep our
+         * options open should we later on need it. */
+        *timeout_usec = (uint64_t) -1;
+        return 0;
+}
diff --git a/src/login/test-login.c b/src/login/test-login.c
index f639129636..e4d0c93378 100644
--- a/src/login/test-login.c
+++ b/src/login/test-login.c
@@ -183,12 +183,23 @@ int main(int argc, char* argv[]) {
         r = sd_login_monitor_new("session", &m);
         assert_se(r >= 0);
 
-        zero(pollfd);
-        pollfd.fd = sd_login_monitor_get_fd(m);
-        pollfd.events = sd_login_monitor_get_events(m);
 
         for (n = 0; n < 5; n++) {
-                r = poll(&pollfd, 1, -1);
+                usec_t timeout, nw;
+
+                zero(pollfd);
+                assert_se((pollfd.fd = sd_login_monitor_get_fd(m)) >= 0);
+                assert_se((pollfd.events = sd_login_monitor_get_events(m)) >= 0);
+
+                assert_se(sd_login_monitor_get_timeout(m, &timeout) >= 0);
+
+                nw = now(CLOCK_MONOTONIC);
+
+                r = poll(&pollfd, 1,
+                         timeout == (uint64_t) -1 ? -1 :
+                         timeout > nw ? (int) ((timeout - nw) / 1000) :
+                         0);
+
                 assert_se(r >= 0);
 
                 sd_login_monitor_flush(m);
diff --git a/src/systemd/sd-login.h b/src/systemd/sd-login.h
index 57255bd4a9..d05424dbf3 100644
--- a/src/systemd/sd-login.h
+++ b/src/systemd/sd-login.h
@@ -23,6 +23,7 @@
 ***/
 
 #include <sys/types.h>
+#include <inttypes.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -159,6 +160,9 @@ int sd_login_monitor_get_fd(sd_login_monitor *m);
 /* Get poll() mask to monitor */
 int sd_login_monitor_get_events(sd_login_monitor *m);
 
+/* Get timeout for poll(), as usec value relative to CLOCK_MONOTONIC's epoch */
+int sd_login_monitor_get_timeout(sd_login_monitor *m, uint64_t *timeout_usec);
+
 #ifdef __cplusplus
 }
 #endif