dennwc
diff --git a/‎btrfs_h.go‎
Lines changed: 2 additions & 0 deletions b/‎btrfs_h.go‎
Lines changed: 2 additions & 0 deletions
diff --git a/‎btrfs_tree.go‎
Lines changed: 54 additions & 0 deletions b/‎btrfs_tree.go‎
Lines changed: 54 additions & 0 deletions
@@ -2,6 +2,8 @@ package btrfs
 
 import "strings"
 
+const maxUint64 = 1<<64 - 1
+
 const BTRFS_LABEL_SIZE = 256
 
 type FeatureFlags uint64
 
@@ -0,0 +1,54 @@
+package btrfs
+
+import (
+	"time"
+	"unsafe"
+)
+
+const (
+	_BTRFS_BLOCK_GROUP_PROFILE_MASK = (blockGroupRaid0 |
+		blockGroupRaid1 |
+		blockGroupRaid5 |
+		blockGroupRaid6 |
+		blockGroupDup |
+		blockGroupRaid10)
+)
+
+type rootRef struct {
+	DirID    uint64
+	Sequence uint64
+	Name     string
+}
+
+func (rootRef) btrfsSize() int { return 18 }
+
+func asUint64(p []byte) uint64 {
+	return *(*uint64)(unsafe.Pointer(&p[0]))
+}
+
+func asUint32(p []byte) uint32 {
+	return *(*uint32)(unsafe.Pointer(&p[0]))
+}
+
+func asUint16(p []byte) uint16 {
+	return *(*uint16)(unsafe.Pointer(&p[0]))
+}
+
+func asTime(p []byte) time.Time {
+	sec, nsec := asUint64(p[0:]), asUint32(p[8:])
+	return time.Unix(int64(sec), int64(nsec))
+}
+
+func asRootRef(p []byte) rootRef {
+	const sz = 18
+	// assuming that it is highly unsafe to have sizeof(struct) > len(data)
+	// (*btrfs_root_ref)(unsafe.Pointer(&p[0])) and sizeof(btrfs_root_ref) == 24
+	ref := rootRef{
+		DirID:    asUint64(p[0:]),
+		Sequence: asUint64(p[8:]),
+	}
+	if n := asUint16(p[16:]); n > 0 {
+		ref.Name = string(p[sz : sz+n : sz+n])
+	}
+	return ref
+}