vut: Don't read VSL from stdin in daemon mode

include/vut_options.h

@@ -93,7 +93,9 @@
 #define VUT_OPT_r							\
 	VOPT("r:", "[-r <filename>]", "Binary file input",		\
 	    "Read log in binary file format from this file. The file"	\
-	    " can be created with ``varnishlog -w filename``."		\
+	    " can be created with ``varnishlog -w filename``. If the"	\
+	    " filename is -, logs are read from the standard input."	\
+	    " and cannot work as a daemon."				\
 	)
 
 #define VUT_OPT_t							\

lib/libvarnishapi/vut.c

@@ -302,6 +302,9 @@ VUT_Setup(struct VUT *vut)
 	    (vut->r_arg == NULL ? 0 : 2) > 2)
 		VUT_Error(vut, 1, "Only one of -n and -r options may be used");
 
+	if (vut->r_arg != NULL && !strcmp(vut->r_arg, "-") && vut->D_opt)
+		VUT_Error(vut, 1, "Daemon cannot read from stdin");
+
 	/* Create and validate the query expression */
 	vut->vslq = VSLQ_New(vut->vsl, NULL,
 	    (enum VSL_grouping_e)vut->g_arg, vut->q_arg);