Split dns_name_copy() into dns_name_copy() and dns_name_copynf()

The dns_name_copy() function followed two different semanitcs that was driven
whether the last argument was or wasn't NULL.  This commit splits the function
in two where now third argument to dns_name_copy() can't be NULL and
dns_name_copynf() doesn't have third argument.

(cherry picked from commit f7aef3738a)

lib/dns/include/dns/name.h

@@ -1240,16 +1240,19 @@ dns_name_settotextfilter(dns_name_totextfilter_t proc);
 
 isc_result_t
 dns_name_copy(const dns_name_t *source, dns_name_t *dest, isc_buffer_t *target);
+void
+dns_name_copynf(const dns_name_t *source, dns_name_t *dest);
 /*%<
- * Makes 'dest' refer to a copy of the name in 'source'.  The data are
- * either copied to 'target' or the dedicated buffer in 'dest'.
+ * Makes 'dest' refer to a copy of the name in 'source'.  The data are either
+ * copied to 'target' or in case of dns_name_copyfixed the dedicated buffer in
+ * 'dest'.
  *
  * Requires:
  * \li	'source' is a valid name.
  *
  * \li	'dest' is an initialized name with a dedicated buffer.
  *
- * \li	'target' is NULL or an initialized buffer.
+ * \li	'target' is an initialized buffer.
  *
  * \li	Either dest has a dedicated buffer or target != NULL.
  *

lib/dns/name.c

@@ -2456,50 +2456,46 @@ dns_name_fromstring2(dns_name_t *target, const char *src,
 	return (result);
 }
 
+static
 isc_result_t
-dns_name_copy(const dns_name_t *source, dns_name_t *dest, isc_buffer_t *target) {
+name_copy(const dns_name_t *source, dns_name_t *dest, isc_buffer_t *target) {
 	unsigned char *ndata;
 
 	/*
 	 * Make dest a copy of source.
 	 */
 
-	REQUIRE(VALID_NAME(source));
-	REQUIRE(VALID_NAME(dest));
-	REQUIRE(target != NULL || dest->buffer != NULL);
-
-	if (target == NULL) {
-		target = dest->buffer;
-		isc_buffer_clear(dest->buffer);
-	}
-
 	REQUIRE(BINDABLE(dest));
 
 	/*
 	 * Set up.
 	 */
-	if (target->length - target->used < source->length)
+	if (target->length - target->used < source->length) {
 		return (ISC_R_NOSPACE);
+	}
 
 	ndata = (unsigned char *)target->base + target->used;
 	dest->ndata = target->base;
 
-	if (source->length != 0)
+	if (source->length != 0) {
 		memmove(ndata, source->ndata, source->length);
+	}
 
 	dest->ndata = ndata;
 	dest->labels = source->labels;
 	dest->length = source->length;
-	if ((source->attributes & DNS_NAMEATTR_ABSOLUTE) != 0)
+	if ((source->attributes & DNS_NAMEATTR_ABSOLUTE) != 0) {
 		dest->attributes = DNS_NAMEATTR_ABSOLUTE;
-	else
+	} else {
 		dest->attributes = 0;
+	}
 
 	if (dest->labels > 0 && dest->offsets != NULL) {
-		if (source->offsets != NULL)
+		if (source->offsets != NULL) {
 			memmove(dest->offsets, source->offsets, source->labels);
-		else
+		} else {
 			set_offsets(dest, dest->offsets, NULL);
+		}
 	}
 
 	isc_buffer_add(target, dest->length);
@@ -2507,6 +2503,27 @@ dns_name_copy(const dns_name_t *source, dns_name_t *dest, isc_buffer_t *target)
 	return (ISC_R_SUCCESS);
 }
 
+isc_result_t
+dns_name_copy(const dns_name_t *source, dns_name_t *dest, isc_buffer_t *target)
+{
+	REQUIRE(VALID_NAME(source));
+	REQUIRE(VALID_NAME(dest));
+	REQUIRE(target != NULL);
+
+	return (name_copy(source, dest, target));
+}
+
+void
+dns_name_copynf(const dns_name_t *source, dns_name_t *dest)
+{
+	REQUIRE(VALID_NAME(source));
+	REQUIRE(VALID_NAME(dest));
+	REQUIRE(dest->buffer != NULL);
+
+	isc_buffer_clear(dest->buffer);
+	RUNTIME_CHECK(name_copy(source, dest, dest->buffer) == ISC_R_SUCCESS);
+}
+
 void
 dns_name_destroy(void) {
 	RUNTIME_CHECK(isc_once_do(&once, thread_key_mutex_init)

lib/dns/win32/libdns.def.in

@@ -540,6 +540,7 @@ dns_name_clone
 dns_name_compare
 dns_name_concatenate
 dns_name_copy
+dns_name_copynf
 dns_name_countlabels
 dns_name_destroy
 dns_name_digest