core: Log in more scenarios about which process initiated an operation

Exit/Reboot/Poweroff and similar operations are invasive enough that
logging about who initiated them is very useful to debug issues.

src/core/dbus-manager.c

@@ -1665,6 +1665,8 @@ static int method_exit(sd_bus_message *message, void *userdata, sd_bus_error *er
         if (r < 0)
                 return r;
 
+        log_caller(message, m, "Exit");
+
         /* Exit() (in contrast to SetExitCode()) is actually allowed even if
          * we are running on the host. It will fall back on reboot() in
          * systemd-shutdown if it cannot do the exit() because it isn't a
@@ -1689,6 +1691,8 @@ static int method_reboot(sd_bus_message *message, void *userdata, sd_bus_error *
         if (r < 0)
                 return r;
 
+        log_caller(message, m, "Reboot");
+
         m->objective = MANAGER_REBOOT;
 
         return sd_bus_reply_method_return(message, NULL);
@@ -1731,6 +1735,8 @@ static int method_soft_reboot(sd_bus_message *message, void *userdata, sd_bus_er
                         return r;
         }
 
+        log_caller(message, m, "Soft reboot");
+
         free_and_replace(m->switch_root, rt);
         m->objective = MANAGER_SOFT_REBOOT;
 
@@ -1751,6 +1757,8 @@ static int method_poweroff(sd_bus_message *message, void *userdata, sd_bus_error
         if (r < 0)
                 return r;
 
+        log_caller(message, m, "Poweroff");
+
         m->objective = MANAGER_POWEROFF;
 
         return sd_bus_reply_method_return(message, NULL);
@@ -1770,6 +1778,8 @@ static int method_halt(sd_bus_message *message, void *userdata, sd_bus_error *er
         if (r < 0)
                 return r;
 
+        log_caller(message, m, "Halt");
+
         m->objective = MANAGER_HALT;
 
         return sd_bus_reply_method_return(message, NULL);
@@ -1789,6 +1799,8 @@ static int method_kexec(sd_bus_message *message, void *userdata, sd_bus_error *e
         if (r < 0)
                 return r;
 
+        log_caller(message, m, "Kexec");
+
         m->objective = MANAGER_KEXEC;
 
         return sd_bus_reply_method_return(message, NULL);