sub() method and function fail if the text param is NULL

src/tests/sub.vtc

@@ -63,6 +63,12 @@ varnish v1 -vcl {
 		# Undefined pattern in the function
 		set resp.http.undefpattern
 			= re2.sub(req.http.undef, "", "", "pattern undef");
+
+		# Undefined text
+		set resp.http.undeftext
+			= b.sub(req.http.undef, "x", "text undef");
+		set resp.http.undeftextf
+			= re2.sub("b", req.http.undef, "x", "text undef");
 	}
 
 } -start
@@ -99,12 +105,19 @@ client c1 {
 	expect resp.http.undeffallbackf == "**SUB FUNCTION FAILED**"
 
 	expect resp.http.undefpattern == "pattern undef"
+
+	expect resp.http.undeftext == "text undef"
+	expect resp.http.undeftextf == "text undef"
 } -run
 
 logexpect l1 -v v1 -d 1 -g vxid -q "VCL_Error" {
 	expect 0 * Begin req
+
 	expect * = VCL_Error "^vmod re2 error: b.sub..: fallback is undefined$"
 	expect * = VCL_Error "^vmod re2 error: re2.sub..: fallback is undefined$"
 	expect * = VCL_Error "^vmod re2 error: re2.sub.pattern=<undefined>, fallback=.pattern undef..: pattern is undefined$"
+
+	expect * = VCL_Error "^vmod re2 error: b.sub.text=<undefined>, fallback=.text undef..: text is undefined$"
+	expect * = VCL_Error "^vmod re2 error: re2.sub.pattern=.b., text=<undefined>, fallback=.text undef..: text is undefined$"
 	expect * = End
 } -run

src/vmod_re2.c

@@ -430,8 +430,11 @@ vmod_regex_sub(VRT_CTX, struct vmod_re2_regex *re, VCL_STRING text,
 		VERR(ctx, "%s.sub(): fallback is undefined", re->vcl_name);
 		return "**SUB METHOD FAILED**";
 	}
-	if (text == NULL)
-		text = "";
+	if (text == NULL) {
+		VERR(ctx, "%s.sub(text=<undefined>, fallback=\"%s\"): "
+		     "text is undefined", re->vcl_name, fallback);
+		return fallback;
+	}
 	if (rewrite == NULL)
 		rewrite = "";
 
@@ -747,8 +750,11 @@ vmod_sub(VRT_CTX, VCL_STRING pattern, VCL_STRING text, VCL_STRING rewrite,
 		     "pattern is undefined", fallback);
 		return fallback;
 	}
-	if (text == NULL)
-		text = "";
+	if (text == NULL) {
+		VERR(ctx, "re2.sub(pattern=\"%s\", text=<undefined>, "
+		     "fallback=\"%s\"): text is undefined", pattern, fallback);
+		return fallback;
+	}
 	if (rewrite == NULL)
 		rewrite = "";