Add nv_assert() which allows to assert that the given name exists.

MFC after:	1 week

sbin/hastd/nv.c

@@ -563,11 +563,10 @@ nv_get_string(struct nv *nv, const char *namefmt, ...)
 	return (str);
 }
 
-bool
+static bool
-nv_exists(struct nv *nv, const char *namefmt, ...)
+nv_vexists(struct nv *nv, const char *namefmt, va_list nameap)
 {
 	struct nvhdr *nvh;
-	va_list nameap;
 	int snverror, serrno;
 
 	if (nv == NULL)
@@ -576,9 +575,7 @@ nv_exists(struct nv *nv, const char *namefmt, ...)
 	serrno = errno;
 	snverror = nv->nv_error;
 
-	va_start(nameap, namefmt);
 	nvh = nv_find(nv, NV_TYPE_NONE, namefmt, nameap);
-	va_end(nameap);
 
 	errno = serrno;
 	nv->nv_error = snverror;
@@ -586,6 +583,29 @@ nv_exists(struct nv *nv, const char *namefmt, ...)
 	return (nvh != NULL);
 }
 
+bool
+nv_exists(struct nv *nv, const char *namefmt, ...)
+{
+	va_list nameap;
+	bool ret;
+
+	va_start(nameap, namefmt);
+	ret = nv_vexists(nv, namefmt, nameap);
+	va_end(nameap);
+
+	return (ret);
+}
+
+void
+nv_assert(struct nv *nv, const char *namefmt, ...)
+{
+	va_list nameap;
+
+	va_start(nameap, namefmt);
+	assert(nv_vexists(nv, namefmt, nameap));
+	va_end(nameap);
+}
+
 /*
  * Dump content of the nv structure.
  */

sbin/hastd/nv.h

@@ -127,6 +127,7 @@ const char *nv_get_string(struct nv *nv, const char *namefmt, ...)
     __printflike(2, 3);
 
 bool nv_exists(struct nv *nv, const char *namefmt, ...) __printflike(2, 3);
+void nv_assert(struct nv *nv, const char *namefmt, ...) __printflike(2, 3);
 void nv_dump(struct nv *nv);
 
 #endif	/* !_NV_H_ */