-void hfs_swap_HFSPlusForkData (HFSPlusForkData *src);
-int hfs_swap_BTNode (BlockDescriptor *src, int isHFSPlus, HFSCatalogNodeID fileID, int unswap);
+/*
+ * Constants for the "unswap" argument to hfs_swap_BTNode:
+ */
+enum HFSBTSwapDirection {
+ kSwapBTNodeBigToHost = 0,
+ kSwapBTNodeHostToBig = 1,
+
+ /*
+ * kSwapBTNodeHeaderRecordOnly is used to swap just the header record
+ * of a header node from big endian (on disk) to host endian (in memory).
+ * It does not swap the node descriptor (forward/backward links, record
+ * count, etc.). It assumes the header record is at offset 0x000E.
+ *
+ * Since HFS Plus doesn't have fixed B-tree node sizes, we have to read
+ * the header record to determine the actual node size for that tree
+ * before we can set up the B-tree control block. We read it initially
+ * as 512 bytes, then re-read it once we know the correct node size. Since
+ * we may not have read the entire header node the first time, we can't
+ * swap the record offsets, other records, or do most sanity checks.
+ */
+ kSwapBTNodeHeaderRecordOnly = 3
+};
+
+int hfs_swap_BTNode (BlockDescriptor *src, vnode_t vp, enum HFSBTSwapDirection direction);