Add the .check_call() method.

README.md

@@ -1533,6 +1533,15 @@ Example:
 
 XXX ...
 
+#### BOOL xset.check\_call(INT n, ENUM select)
+
+    BOOL xset.check_call(
+          INT n=0,
+          ENUM {FIRST, LAST, UNIQUE} select=UNIQUE
+    )
+
+XXX ...
+
 #### BOOL xset.saved(ENUM which, INT n, ENUM select)
 
     BOOL xset.saved(

src/set.c

@@ -782,6 +782,81 @@ vmod_set_subroutine(VRT_CTX, struct VPFX(re2_set) *set, VCL_INT n,
 	return set->sub[idx];
 }
 
+VCL_BOOL
+vmod_set_check_call(VRT_CTX, struct VPFX(re2_set) *set, VCL_INT n,
+		    VCL_ENUM selects)
+{
+	struct task_set_match *task;
+	int idx = 0;
+	VCL_STRING err;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(set, VMOD_RE2_SET_MAGIC);
+	if (set->sub == NULL) {
+		VNOTICE(ctx,
+			"%s.check_call(%jd): No subroutines were set for %s",
+			set->vcl_name, (intmax_t)n, set->vcl_name);
+		return (0);
+	}
+
+	/*
+	 * XXX: considerable DRY with get_match_idx().
+	 * get_match_idx() invokes VRT_fail(), but we need to log
+	 * SLT_Notice here, and the two alternatives are hard to
+	 * disentangle within get_match_idx(). An alternative would be to
+	 * pass in a flag to get_match_idx() that chooses between the two,
+	 * and then we have to add the flag everywhere else. Consider
+	 * that if we add anything else that needs SLT_Notice.
+	 */
+	if (n > set->npatterns) {
+		VNOTICE(ctx, "%s.check_call(%jd): set has %d patterns",
+			set->vcl_name, (intmax_t)n, set->npatterns);
+		return (0);
+	}
+	if (n <= 0) {
+		if ((task = get_task_data(ctx, set)) == NULL) {
+			VNOTICE(ctx,
+				"%s.check_call() called without prior match",
+				set->vcl_name);
+			return (0);
+		}
+		if (task->nmatches == 0) {
+			VNOTICE(ctx, "%s.check_call(%jd): previous match was "
+				"unsuccessful", set->vcl_name, (intmax_t)n);
+			return (0);
+		}
+		if (task->nmatches > 1) {
+			if (selects == VENUM(UNIQUE)) {
+				VNOTICE(ctx, "%s.check_call(%jd): %ld "
+					"successful matches", set->vcl_name,
+					(intmax_t)n, task->nmatches);
+				return (0);
+			}
+			if (selects == VENUM(LAST))
+				idx = task->nmatches - 1;
+			else
+				assert(selects == VENUM(FIRST));
+		}
+		WS_Assert_Allocated(ctx->ws, task->matches,
+				    task->nmatches * sizeof(int));
+		idx = task->matches[idx];
+	}
+
+	if (!vbit_test(set->added[SUBROUTINE], idx)) {
+		AN(selects);
+		VNOTICE(ctx,
+			"%s.check_call(%jd, %s): subroutine %d was not added",
+			set->vcl_name, n, selects, idx + 1);
+		return (0);
+	}
+	if ((err = VRT_check_call(ctx, set->sub[idx])) != NULL) {
+		VNOTICE(ctx, "%s.check_call(): %s", set->vcl_name, err);
+		return (0);
+	}
+
+	return (1);
+}
+
 VCL_BOOL
 vmod_set_saved(VRT_CTX, struct vmod_re2_set *set, VCL_ENUM whichs, VCL_INT n,
 	       VCL_ENUM selects)

src/vmod_re2.h

@@ -47,6 +47,9 @@
 #define VERRNOMEM(ctx, fmt, ...) \
 	VFAIL((ctx), fmt ", out of space", __VA_ARGS__)
 
+#define VNOTICE(ctx, fmt, ...) \
+	VSLb((ctx)->vsl, SLT_Notice, "vmod_re2: " fmt, __VA_ARGS__)
+
 struct vmod_re2_regex {
 	unsigned	magic;
 #define VMOD_RE2_REGEX_MAGIC 0x5c3f6f24

src/vmod_re2.vcc

@@ -1401,6 +1401,10 @@ $Method SUB .subroutine(INT n=0, ENUM {FIRST, LAST, UNIQUE} select=UNIQUE)
 
 XXX ...
 
+$Method BOOL .check_call(INT n=0, ENUM {FIRST, LAST, UNIQUE} select=UNIQUE)
+
+XXX ...
+
 $Method BOOL .saved(ENUM {REGEX, STR, BE, INT, SUB} which=REGEX, INT n=0,
                     ENUM {FIRST, LAST, UNIQUE} select=UNIQUE)