+static uschar queuerun_msgid[MESSAGE_ID_LENGTH+1];
+
+/* Return TRUE if a sigalrm should be emulated */
+static BOOL
+daemon_notification(void)
+{
+uschar buf[256], cbuf[256];
+struct sockaddr_un sa_un;
+struct iovec iov = {.iov_base = buf, .iov_len = sizeof(buf)-1};
+struct msghdr msg = { .msg_name = &sa_un,
+ .msg_namelen = sizeof(sa_un),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = cbuf,
+ .msg_controllen = sizeof(cbuf)
+ };
+ssize_t sz;
+struct cmsghdr * cp;
+
+buf[sizeof(buf)-1] = 0;
+if ((sz = recvmsg(daemon_notifier_fd, &msg, 0)) <= 0) return FALSE;
+if (sz >= sizeof(buf)) return FALSE;
+
+#ifdef notdef
+debug_printf("addrlen %d\n", msg.msg_namelen);
+#endif
+DEBUG(D_queue_run) debug_printf("%s from addr '%s%.*s'\n", __FUNCTION__,
+ *sa_un.sun_path ? "" : "@",
+ (int)msg.msg_namelen - (*sa_un.sun_path ? 0 : 1),
+ sa_un.sun_path + (*sa_un.sun_path ? 0 : 1));
+
+/* Refuse to handle the item unless the peer has good credentials */
+#ifdef SCM_CREDENTIALS
+# define EXIM_SCM_CR_TYPE SCM_CREDENTIALS
+#elif defined(LOCAL_CREDS) && defined(SCM_CREDS)
+# define EXIM_SCM_CR_TYPE SCM_CREDS
+#else
+ /* The OS has no way to get the creds of the caller (for a unix/datagram socket.
+ Punt; don't try to check. */
+#endif
+
+#ifdef EXIM_SCM_CR_TYPE
+for (struct cmsghdr * cp = CMSG_FIRSTHDR(&msg);
+ cp;
+ cp = CMSG_NXTHDR(&msg, cp))
+ if (cp->cmsg_level == SOL_SOCKET && cp->cmsg_type == EXIM_SCM_CR_TYPE)
+ {
+# ifdef SCM_CREDENTIALS /* Linux */
+ struct ucred * cr = (struct ucred *) CMSG_DATA(cp);
+ if (cr->uid && cr->uid != exim_uid)
+ {
+ DEBUG(D_queue_run) debug_printf("%s: sender creds pid %d uid %d gid %d\n",
+ __FUNCTION__, (int)cr->pid, (int)cr->uid, (int)cr->gid);
+ return FALSE;
+ }
+# elif defined(LOCAL_CREDS) /* BSD-ish */
+ struct sockcred * cr = (struct sockcred *) CMSG_DATA(cp);
+ if (cr->sc_uid && cr->sc_uid != exim_uid)
+ {
+ DEBUG(D_queue_run) debug_printf("%s: sender creds pid ??? uid %d gid %d\n",
+ __FUNCTION__, (int)cr->sc_uid, (int)cr->sc_gid);
+ return FALSE;
+ }
+# endif
+ break;
+ }
+#endif
+
+buf[sz] = 0;
+switch (buf[0])
+ {
+#ifdef EXPERIMENTAL_QUEUE_RAMP
+ case NOTIFY_MSG_QRUN:
+ /* this should be a message_id */
+ DEBUG(D_queue_run)
+ debug_printf("%s: qrunner trigger: %s\n", __FUNCTION__, buf+1);
+ memcpy(queuerun_msgid, buf+1, MESSAGE_ID_LENGTH+1);
+ return TRUE;
+#endif /*EXPERIMENTAL_QUEUE_RAMP*/
+
+ case NOTIFY_QUEUE_SIZE_REQ:
+ {
+ uschar buf[16];
+ int len = snprintf(CS buf, sizeof(buf), "%u", queue_count_cached());
+
+ DEBUG(D_queue_run)
+ debug_printf("%s: queue size request: %s\n", __FUNCTION__, buf);
+
+ if (sendto(daemon_notifier_fd, buf, len, 0,
+ (const struct sockaddr *)&sa_un, msg.msg_namelen) < 0)
+ log_write(0, LOG_MAIN|LOG_PANIC,
+ "%s: sendto: %s\n", __FUNCTION__, strerror(errno));
+ return FALSE;
+ }
+ }
+return FALSE;
+}
+