set.string() and .backend() when no strings or backends were set.

src/tests/set_retrieve.vtc

@@ -11,6 +11,10 @@ varnish v1 -vcl {
 		s.add("foo", "baz");
 		s.add("bar", "quux");
 		s.compile();
+
+		new n = re2.set();
+		n.add("foo");
+		n.compile();
 	}
 
 	sub vcl_recv {
@@ -38,6 +42,13 @@ varnish v1 -vcl {
 		set resp.http.s-many-first = s.string(select=FIRST);
 		set resp.http.s-many-last = s.string(select=LAST);
 		set resp.http.s-outofrange = s.string(3);
+
+		set resp.http.n-str-1 = n.string(1);
+		set resp.http.n-str-2 = n.string(2);
+		set resp.http.n-before-match = n.string();
+		set resp.http.n-foo-match = n.match("foo");
+		set resp.http.n-foo-n = n.nmatches();
+		set resp.http.n-foo-str = n.string();
 	}
 
 } -start
@@ -66,6 +77,12 @@ client c1 {
 	expect resp.http.s-many-first == "baz"
 	expect resp.http.s-many-last == "quux"
 	expect resp.http.s-outofrange == ""
+	expect resp.http.n-str-1 == ""
+	expect resp.http.n-str-2 == ""
+	expect resp.http.n-before-match == ""
+	expect resp.http.n-foo-match == "true"
+	expect resp.http.n-foo-n == 1
+	expect resp.http.n-foo-str == ""
 } -run
 
 logexpect l1 -v v1 -d 1 -g vxid -q "VCL_Error" {
@@ -75,6 +92,10 @@ logexpect l1 -v v1 -d 1 -g vxid -q "VCL_Error" {
 	expect * = VCL_Error "^vmod re2 error: s.string.0.: previous match was unsuccessful$"
 	expect * = VCL_Error "^vmod re2 error: s.string.0.: 2 successful matches$"
 	expect * = VCL_Error "^vmod re2 error: s.string.3.: set has 2 patterns$"
+	expect * = VCL_Error "^vmod re2 error: n.string.1.: No strings were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.string.2.: No strings were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.string.0.: No strings were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.string.0.: No strings were set for n$"
 
 	expect * = End
 } -run
@@ -89,6 +110,10 @@ varnish v1 -vcl {
 		b.add("foo", backend=b1);
 		b.add("bar", backend=b2);
 		b.compile();
+
+		new n = re2.set();
+		n.add("foo");
+		n.compile();
 	}
 
 	sub vcl_recv {
@@ -116,6 +141,13 @@ varnish v1 -vcl {
 		set resp.http.b-many-first = b.backend(select=FIRST);
 		set resp.http.b-many-last = b.backend(select=LAST);
 		set resp.http.b-outofrange = b.backend(3);
+
+		set resp.http.n-backend-1 = n.backend(1);
+		set resp.http.n-backend-2 = n.backend(2);
+		set resp.http.n-before-match = n.backend();
+		set resp.http.n-foo-match = n.match("foo");
+		set resp.http.n-foo-n = n.nmatches();
+		set resp.http.n-foo-backend = n.backend();
 	}
 
 }
@@ -127,6 +159,10 @@ logexpect l1 -v v1 -d 0 -g vxid -q "VCL_Error" {
 	expect * = VCL_Error "^vmod re2 error: b.backend.0.: previous match was unsuccessful$"
 	expect * = VCL_Error "^vmod re2 error: b.backend.0.: 2 successful matches$"
 	expect * = VCL_Error "^vmod re2 error: b.backend.3.: set has 2 patterns$"
+	expect * = VCL_Error "^vmod re2 error: n.backend.1.: No backends were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.backend.2.: No backends were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.backend.0.: No backends were set for n$"
+	expect * = VCL_Error "^vmod re2 error: n.backend.0.: No backends were set for n$"
 
 	expect * = End
 } -start

src/vmod_re2.c

@@ -857,7 +857,17 @@ get_match_idx(VRT_CTX, struct vmod_re2_set *set, VCL_INT n, VCL_ENUM selects,
 VCL_STRING
 vmod_set_string(VRT_CTX, struct vmod_re2_set *set, VCL_INT n, VCL_ENUM selects)
 {
-	int idx = get_match_idx(ctx, set, n, selects, "string");
+	int idx;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(set, VMOD_RE2_SET_MAGIC);
+	if (set->string == NULL) {
+		VERR(ctx, "%s.string(%lld): No strings were set for %s",
+		     set->vcl_name, n, set->vcl_name);
+		return NULL;
+	}
+
+	idx = get_match_idx(ctx, set, n, selects, "string");
 	if (idx < 0)
 		return NULL;
 	return set->string[idx];
@@ -866,7 +876,17 @@ vmod_set_string(VRT_CTX, struct vmod_re2_set *set, VCL_INT n, VCL_ENUM selects)
 VCL_BACKEND
 vmod_set_backend(VRT_CTX, struct vmod_re2_set *set, VCL_INT n, VCL_ENUM selects)
 {
-	int idx = get_match_idx(ctx, set, n, selects, "backend");
+	int idx;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(set, VMOD_RE2_SET_MAGIC);
+	if (set->backend == NULL) {
+		VERR(ctx, "%s.backend(%lld): No backends were set for %s",
+		     set->vcl_name, n, set->vcl_name);
+		return NULL;
+	}
+
+	idx = get_match_idx(ctx, set, n, selects, "backend");
 	if (idx < 0)
 		return NULL;
 	return set->backend[idx];