Fix systemctl start --verbose off-by-one logs (#39927)

src/journal/journalctl-show.c

@@ -362,7 +362,9 @@ static int on_first_event(sd_event_source *s, void *userdata) {
                         return log_error_errno(r, "Failed to get cursor: %m");
         }
 
+        /* Setup and initial processing are done, we're ready to wait for more data. */
         (void) sd_notify(/* unset_environment= */ false, "READY=1");
+
         return 0;
 }
 
@@ -472,11 +474,9 @@ static int setup_event(Context *c, int fd) {
         else if (r < 0)
                 return log_error_errno(r, "Failed to add io event source for stdout: %m");
 
-        if (arg_lines != 0 || arg_since_set) {
-                r = sd_event_add_defer(e, NULL, on_first_event, c);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to add defer event source: %m");
-        }
+        r = sd_event_add_defer(e, NULL, on_first_event, c);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add defer event source: %m");
 
         c->event = TAKE_PTR(e);
         return 0;
@@ -583,6 +583,7 @@ int action_show(char **matches) {
                 return 0;
         }
 
+        /* Setup is done, we'll start processing data. */
         (void) sd_notify(/* unset_environment= */ false, "READY=1");
 
         r = show(&c);

src/libsystemd/sd-daemon/sd-daemon.c

@@ -505,13 +505,14 @@ static int pid_notify_with_fds_internal(
         if (r == -EPROTO)
                 r = socket_address_parse_vsock(&address, e);
         if (r < 0)
-                return r;
+                return log_debug_errno(r, "Address NOTIFY_SOCKET='%s' is neither UNIX nor VSOCK, refusing: %m", e);
         msghdr.msg_namelen = address.size;
 
         /* If we didn't get an address (which is a normal pattern when specifying VSOCK tuples) error out,
          * we always require a specific CID. */
         if (address.sockaddr.vm.svm_family == AF_VSOCK && address.sockaddr.vm.svm_cid == VMADDR_CID_ANY)
-                return -EINVAL;
+                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "VSOCK address in NOTIFY_SOCKET='%s' doesn't have CID, refusing.", e);
 
         type = address.type == 0 ? SOCK_DGRAM : address.type;
 
@@ -610,7 +611,8 @@ static int pid_notify_with_fds_internal(
                 } else {
                         /* Unless we're using SOCK_STREAM, we expect to write all the contents immediately. */
                         if (type != SOCK_STREAM && (size_t) n < iovec_total_size(msghdr.msg_iov, msghdr.msg_iovlen))
-                                return -EIO;
+                                return log_debug_errno(SYNTHETIC_ERRNO(EIO),
+                                                       "Incomplete notify message sent to '%s': %m", e);
 
                         /* Make sure we only send fds and ucred once, even if we're using SOCK_STREAM. */
                         msghdr.msg_control = NULL;
@@ -631,6 +633,7 @@ static int pid_notify_with_fds_internal(
                         return log_debug_errno(SYNTHETIC_ERRNO(EPROTO), "Unexpectedly received data on notify socket.");
         }
 
+        log_debug("Notify message sent to '%s': \"%s\"", e, state);
         return 1;
 }
 

src/shared/fork-notify.c

@@ -219,7 +219,7 @@ int journal_fork(RuntimeScope scope, char * const* units, PidRef *ret_pidref) {
                         "-q",
                         "--follow",
                         "--no-pager",
-                        "--lines=1",
+                        "--lines=0",
                         "--synchronize-on-exit=yes");
         if (!argv)
                 return log_oom_debug();