Tighten up checks

lib/libvarnish/vtim.c

@@ -243,6 +243,9 @@ VTIM_parse(const char *p)
 	int hour = 0, min = 0, sec = 0;
 	int d, leap;
 
+	if (p == NULL || *p == '\0')
+		FAIL();
+
 	while (*p == ' ')
 		p++;
 

lib/libvmod_std/vmod_std_conversions.c

@@ -194,8 +194,6 @@ vmod_time(VRT_CTX, VCL_STRING p, VCL_TIME d)
 
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 
-	if (p == NULL)
-		return (d);
 	r = VTIM_parse(p);
 	if (r)
 		return (r);

lib/libvmod_std/vmod_std_fileread.c

@@ -90,6 +90,9 @@ vmod_fileread(VRT_CTX, struct vmod_priv *priv,
 	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
 	AN(priv);
 
+	if (file_name == NULL)
+		return (NULL);
+
 	if (priv->priv != NULL) {
 		CAST_OBJ_NOTNULL(frf, priv->priv, CACHED_FILE_MAGIC);
 		if (!strcmp(file_name, frf->file_name))