utils: Wait for user if there are no user sessions

At system start systemd will create user session, but this could be
after mtp is started. This patch makes the user-finding function wait
for user to appear.

Change-Id: I80ccbb69faf9085f7cef30e51a09ef4f785c0bd0
Signed-off-by: Paweł Szewczyk <p.szewczyk@samsung.com>

diff --git a/src/util/mtp_util.c b/src/util/mtp_util.c
index 273fd13..67545c7 100755 (executable)
--- a/src/util/mtp_util.c
+++ b/src/util/mtp_util.c
@@ -35,6 +35,10 @@
 //#include <grp.h>
 #include <media_content_internal.h>
 #include <pwd.h>
+#include <poll.h>
+
+/* time to wait for user session creation, in ms */
+#define WAIT_FOR_USER_TIMEOUT 10000
 
 static phone_state_t g_ph_status = { 0 };
 
@@ -360,13 +364,46 @@ void _util_get_external_path(char *external_path)
                        strncpy(external_path, MTP_EXTERNAL_PATH_CHAR, strlen(MTP_EXTERNAL_PATH_CHAR) + 1);
        }
 }
+
+int _util_wait_for_user()
+{
+       __attribute__((cleanup(sd_login_monitor_unrefp))) sd_login_monitor *monitor = NULL;
+       int ret;
+       struct pollfd fds;
+
+       ret = sd_login_monitor_new("uid", &monitor);
+       if (ret < 0) {
+               ERR("Failed to allocate login monitor object: %s", strerror(-ret));
+               return ret;
+       }
+
+       fds.fd = sd_login_monitor_get_fd(monitor);
+       fds.events = sd_login_monitor_get_events(monitor);
+
+       ret = poll(&fds, 1, WAIT_FOR_USER_TIMEOUT);
+       if (ret < 0) {
+               ERR("Error polling: %m");
+               return -1;
+       }
+
+       return 0;
+}
+
 uid_t _util_get_active_user()
 {
        uid_t *active_user_list = NULL;
        uid_t active_user = 0;
        int user_cnt = 0;
+       int ret;
 
        user_cnt = sd_get_active_uids(&active_user_list);
+       if (user_cnt <= 0) {
+               ret = _util_wait_for_user();
+               if (ret < 0)
+                       return -1;
+
+               user_cnt = sd_get_active_uids(&active_user_list);
+       }
 
        if (user_cnt <= 0) {
                ERR("Active user not exists : %d", user_cnt);