Properly implement EXTENT_DATA_REF_KEY inside of an inline ref

3 files changed, 54 insertions, 21 deletions

diff --git a/pkg/btrfs/btrfsitem/item_extent.go b/pkg/btrfs/btrfsitem/item_extent.go
index 778b67f..ab8a4c6 100644
--- a/pkg/btrfs/btrfsitem/item_extent.go
+++ b/pkg/btrfs/btrfsitem/item_extent.go
@@ -90,43 +90,76 @@ func (f ExtentFlags) Has(req ExtentFlags) bool { return f&req == req }
 func (f ExtentFlags) String() string           { return util.BitfieldString(f, extentFlagNames, util.HexNone) }
 
 type ExtentInlineRef struct {
-	Type          Type   `bin:"off=0, siz=1"`
-	Offset        uint64 `bin:"off=1, siz=8"`
-	binstruct.End `bin:"off=9"`
-	Body          Item `bin:"-"`
+	Type   Type   // only 4 valid values: {TREE,SHARED}_BLOCK_REF_KEY, {EXTENT,SHARED}_DATA_REF_KEY
+	Offset uint64 // only when Type != EXTENT_DATA_REF_KEY
+	Body   Item   // only when Type == *_DATA_REF_KEY
 }
 
 func (o *ExtentInlineRef) UnmarshalBinary(dat []byte) (int, error) {
-	n, err := binstruct.UnmarshalWithoutInterface(dat, o)
-	if err != nil {
-		return n, err
-	}
+	o.Type = Type(dat[0])
+	n := 1
 	switch o.Type {
 	case TREE_BLOCK_REF_KEY, SHARED_BLOCK_REF_KEY:
-		o.Body = Empty{}
+		_n, err := binstruct.Unmarshal(dat[n:], &o.Offset)
+		n += _n
+		if err != nil {
+			return n, err
+		}
 	case EXTENT_DATA_REF_KEY:
-		return n, fmt.Errorf("the C code to do this doesn't make any sense")
+		var dref ExtentDataRef
+		_n, err := binstruct.Unmarshal(dat[n:], &dref)
+		n += _n
+		o.Body = dref
+		if err != nil {
+			return n, err
+		}
 	case SHARED_DATA_REF_KEY:
+		_n, err := binstruct.Unmarshal(dat[n:], &o.Offset)
+		n += _n
+		if err != nil {
+			return n, err
+		}
 		var sref SharedDataRef
-		_n, err := binstruct.Unmarshal(dat[n:], &sref)
+		_n, err = binstruct.Unmarshal(dat[n:], &sref)
 		n += _n
 		o.Body = sref
 		if err != nil {
 			return n, err
 		}
+	default:
+		return n, fmt.Errorf("btrfsitem.ExtentInlineRef.UnmarshalBinary: unexpected item type %v", o.Type)
 	}
 	return n, nil
 }
 
 func (o ExtentInlineRef) MarshalBinary() ([]byte, error) {
-	dat, err := binstruct.MarshalWithoutInterface(o)
-	if err != nil {
-		return dat, err
-	}
-	bs, err := binstruct.Marshal(o.Body)
-	dat = append(dat, bs...)
-	if err != nil {
-		return dat, err
+	dat := []byte{byte(o.Type)}
+	switch o.Type {
+	case TREE_BLOCK_REF_KEY, SHARED_BLOCK_REF_KEY:
+		_dat, err := binstruct.Marshal(o.Offset)
+		dat = append(dat, _dat...)
+		if err != nil {
+			return dat, err
+		}
+	case EXTENT_DATA_REF_KEY:
+		_dat, err := binstruct.Marshal(o.Body)
+		dat = append(dat, _dat...)
+		if err != nil {
+			return dat, err
+		}
+	case SHARED_DATA_REF_KEY:
+		_dat, err := binstruct.Marshal(o.Offset)
+		dat = append(dat, _dat...)
+		if err != nil {
+			return dat, err
+		}
+		_dat, err = binstruct.Marshal(o.Body)
+		dat = append(dat, _dat...)
+		if err != nil {
+			return dat, err
+		}
+	default:
+		return dat, fmt.Errorf("btrfsitem.ExtentInlineRef.MarshalBinary: unexpected item type %v", o.Type)
 	}
 	return dat, nil
 }
diff --git a/pkg/btrfs/btrfsitem/item_extentdataref.go b/pkg/btrfs/btrfsitem/item_extentdataref.go
index c898b72..93585be 100644
--- a/pkg/btrfs/btrfsitem/item_extentdataref.go
+++ b/pkg/btrfs/btrfsitem/item_extentdataref.go
@@ -6,7 +6,7 @@ import (
 )
 
 type ExtentDataRef struct { // EXTENT_DATA_REF=178
-	Root          int64          `bin:"off=0, siz=8"`
+	Root          internal.ObjID `bin:"off=0, siz=8"`
 	ObjectID      internal.ObjID `bin:"off=8, siz=8"`
 	Offset        int64          `bin:"off=16, siz=8"`
 	Count         int32          `bin:"off=24, siz=4"`
diff --git a/pkg/btrfsmisc/print_tree.go b/pkg/btrfsmisc/print_tree.go
index 59ad0f5..3a13504 100644
--- a/pkg/btrfsmisc/print_tree.go
+++ b/pkg/btrfsmisc/print_tree.go
@@ -309,7 +309,7 @@ func printHeaderInfo(node btrfs.Node) {
 func printExtentInlineRefs(refs []btrfsitem.ExtentInlineRef) {
 	for _, ref := range refs {
 		switch subitem := ref.Body.(type) {
-		case btrfsitem.Empty:
+		case nil:
 			switch ref.Type {
 			case btrfsitem.TREE_BLOCK_REF_KEY:
 				fmt.Printf("\t\ttree block backref root %v\n",