So close!

5 files changed, 174 insertions, 2 deletions

diff --git a/cmd/btrfs-dump-tree/main.go b/cmd/btrfs-dump-tree/main.go
index 2428a6c..f5eb6c7 100644
--- a/cmd/btrfs-dump-tree/main.go
+++ b/cmd/btrfs-dump-tree/main.go
@@ -217,8 +217,33 @@ func printTree(fs *btrfs.FS, root btrfs.LogicalAddr) error {
 			//	// TODO
 			//case btrfsitem.EXTENT_CSUM_KEY:
 			//	// TODO
-			//case btrfsitem.EXTENT_DATA_KEY:
-			//	// TODO
+			case btrfsitem.FileExtent:
+				fmt.Printf("\t\tgeneration %d type %v\n",
+					body.Generation, body.Type)
+				switch body.Type {
+				case btrfsitem.FILE_EXTENT_INLINE:
+					fmt.Printf("\t\tinline extent data size %d ram_bytes %d compression %v\n",
+						len(body.BodyInline), body.RAMBytes, body.Compression)
+				case btrfsitem.FILE_EXTENT_PREALLOC:
+					fmt.Printf("\t\tprealloc data disk byte %d nr %d\n",
+						body.BodyPrealloc.DiskByteNr,
+						body.BodyPrealloc.DiskNumBytes)
+					fmt.Printf("\t\tprealloc data offset %d nr %d\n",
+						body.BodyPrealloc.Offset,
+						body.BodyPrealloc.NumBytes)
+				case btrfsitem.FILE_EXTENT_REG:
+					fmt.Printf("\t\textent data disk byte %d nr %d\n",
+						body.BodyReg.DiskByteNr,
+						body.BodyReg.DiskNumBytes)
+					fmt.Printf("\t\textenti data offset %d nr %d ram %d\n",
+						body.BodyReg.Offset,
+						body.BodyReg.NumBytes,
+						body.RAMBytes)
+					fmt.Printf("\t\textent compression %v\n",
+						body.Compression)
+				default:
+					fmt.Printf("\t\t(error) unknown file extent type %v", body.Type)
+				}
 			case btrfsitem.BlockGroup:
 				fmt.Printf("\t\tblock group used %d chunk_objectid %d flags %v\n",
 					body.Used, body.ChunkObjectID, body.Flags)
diff --git a/pkg/btrfs/btrfsitem/item_fileextent.go b/pkg/btrfs/btrfsitem/item_fileextent.go
new file mode 100644
index 0000000..0f7fab4
--- /dev/null
+++ b/pkg/btrfs/btrfsitem/item_fileextent.go
@@ -0,0 +1,141 @@
+package btrfsitem
+
+import (
+	"fmt"
+
+	"lukeshu.com/btrfs-tools/pkg/binstruct"
+)
+
+type FileExtent struct { // EXTENT_DATA=108
+	Generation int64 `bin:"off=0x0, siz=0x8"` // transaction ID that created this extent
+	RAMBytes   int64 `bin:"off=0x8, siz=0x8"` // upper bound of what compressed data will decompress to
+
+	// 32 bits describing the data encoding
+	Compression   CompressionType `bin:"off=0x10, siz=0x1"`
+	Encryption    uint8           `bin:"off=0x11, siz=0x1"`
+	OtherEncoding uint16          `bin:"off=0x12, siz=0x2"` // reserved for later use
+
+	Type FileExtentType `bin:"off=0x14, siz=0x1"` // inline data or real extent
+
+	binstruct.End `bin:"off=0x15"`
+
+	// only one of these, depending on .Type
+	BodyInline []byte `bin:"-"`
+	BodyReg    struct {
+		// Position within the device
+		DiskByteNr   int64 `bin:"off=0x0, siz=0x8"`
+		DiskNumBytes int64 `bin:"off=0x8, siz=0x8"`
+
+		// Position within the file
+		Offset        int64 `bin:"off=0x10, siz=0x8"`
+		NumBytes      int64 `bin:"off=0x18, siz=0x8"`
+		binstruct.End `bin:"off=0x20"`
+	} `bin:"-"`
+	BodyPrealloc struct {
+		// Position within the device
+		DiskByteNr   int64 `bin:"off=0x0, siz=0x8"`
+		DiskNumBytes int64 `bin:"off=0x8, siz=0x8"`
+
+		// Position within the file
+		Offset        int64 `bin:"off=0x10, siz=0x8"`
+		NumBytes      int64 `bin:"off=0x18, siz=0x8"`
+		binstruct.End `bin:"off=0x20"`
+	} `bin:"-"`
+}
+
+func (o *FileExtent) UnmarshalBinary(dat []byte) (int, error) {
+	n, err := binstruct.UnmarshalWithoutInterface(dat, o)
+	if err != nil {
+		return n, err
+	}
+	switch o.Type {
+	case FILE_EXTENT_INLINE:
+		o.BodyInline = dat[n:]
+		n += len(o.BodyInline)
+	case FILE_EXTENT_REG:
+		_n, err := binstruct.Unmarshal(dat[n:], &o.BodyReg)
+		n += _n
+		if err != nil {
+			return n, err
+		}
+	case FILE_EXTENT_PREALLOC:
+		_n, err := binstruct.Unmarshal(dat[n:], &o.BodyPrealloc)
+		n += _n
+		if err != nil {
+			return n, err
+		}
+	default:
+		return n, fmt.Errorf("unknown file extent type %v", o.Type)
+	}
+	return n, nil
+}
+
+func (o FileExtent) MarshalBinary() ([]byte, error) {
+	dat, err := binstruct.MarshalWithoutInterface(o)
+	if err != nil {
+		return dat, err
+	}
+	switch o.Type {
+	case FILE_EXTENT_INLINE:
+		dat = append(dat, o.BodyInline...)
+	case FILE_EXTENT_REG:
+		bs, err := binstruct.Marshal(o.BodyReg)
+		dat = append(dat, bs...)
+		if err != nil {
+			return dat, err
+		}
+	case FILE_EXTENT_PREALLOC:
+		bs, err := binstruct.Marshal(o.BodyPrealloc)
+		dat = append(dat, bs...)
+		if err != nil {
+			return dat, err
+		}
+	default:
+		return dat, fmt.Errorf("unknown file extent type %v", o.Type)
+	}
+	return dat, nil
+}
+
+type FileExtentType uint8
+
+const (
+	FILE_EXTENT_INLINE = FileExtentType(iota)
+	FILE_EXTENT_REG
+	FILE_EXTENT_PREALLOC
+)
+
+func (fet FileExtentType) String() string {
+	names := map[FileExtentType]string{
+		FILE_EXTENT_INLINE:   "inline",
+		FILE_EXTENT_REG:      "regular",
+		FILE_EXTENT_PREALLOC: "prealloc",
+	}
+	name, ok := names[fet]
+	if !ok {
+		name = "unknown"
+	}
+	return fmt.Sprintf("%d (%s)", fet, name)
+}
+
+type CompressionType uint8
+
+const (
+	COMPRESS_NONE = CompressionType(iota)
+	COMPRESS_ZLIB
+	COMPRESS_LZO
+	COMPRESS_ZSTD
+)
+
+func (ct CompressionType) String() string {
+	names := map[CompressionType]string{
+		COMPRESS_NONE: "none",
+		COMPRESS_ZLIB: "zlib",
+		COMPRESS_LZO:  "lzo",
+		COMPRESS_ZSTD: "zstd",
+	}
+	name, ok := names[ct]
+	if !ok {
+		name = "unknown"
+	}
+	return fmt.Sprintf("%d (%s)", ct, name)
+}
diff --git a/pkg/btrfs/btrfsitem/items.txt b/pkg/btrfs/btrfsitem/items.txt
index e09c866..8320650 100644
--- a/pkg/btrfs/btrfsitem/items.txt
+++ b/pkg/btrfs/btrfsitem/items.txt
@@ -4,6 +4,7 @@ DEV_EXTENT=204 DevExtent
 DEV_ITEM=216 Dev
 DIR_INDEX=96 DirList
 DIR_ITEM=84 DirList
+EXTENT_DATA=108 FileExtent
 EXTENT_DATA_REF=178 ExtentDataRef
 EXTENT_ITEM=168 Extent
 FREE_SPACE_BITMAP=200 FreeSpaceBitmap
diff --git a/pkg/btrfs/btrfsitem/items_gen.go b/pkg/btrfs/btrfsitem/items_gen.go
index 27fc5c2..02e2915 100644
--- a/pkg/btrfs/btrfsitem/items_gen.go
+++ b/pkg/btrfs/btrfsitem/items_gen.go
@@ -15,6 +15,7 @@ const (
 	DEV_ITEM_KEY             = internal.DEV_ITEM_KEY
 	DIR_INDEX_KEY            = internal.DIR_INDEX_KEY
 	DIR_ITEM_KEY             = internal.DIR_ITEM_KEY
+	EXTENT_DATA_KEY          = internal.EXTENT_DATA_KEY
 	EXTENT_DATA_REF_KEY      = internal.EXTENT_DATA_REF_KEY
 	EXTENT_ITEM_KEY          = internal.EXTENT_ITEM_KEY
 	FREE_SPACE_BITMAP_KEY    = internal.FREE_SPACE_BITMAP_KEY
@@ -43,6 +44,7 @@ var keytype2gotype = map[Type]reflect.Type{
 	DEV_ITEM_KEY:             reflect.TypeOf(Dev{}),
 	DIR_INDEX_KEY:            reflect.TypeOf(DirList{}),
 	DIR_ITEM_KEY:             reflect.TypeOf(DirList{}),
+	EXTENT_DATA_KEY:          reflect.TypeOf(FileExtent{}),
 	EXTENT_DATA_REF_KEY:      reflect.TypeOf(ExtentDataRef{}),
 	EXTENT_ITEM_KEY:          reflect.TypeOf(Extent{}),
 	FREE_SPACE_BITMAP_KEY:    reflect.TypeOf(FreeSpaceBitmap{}),
@@ -73,6 +75,7 @@ func (DirList) isItem()         {}
 func (Empty) isItem()           {}
 func (Extent) isItem()          {}
 func (ExtentDataRef) isItem()   {}
+func (FileExtent) isItem()      {}
 func (FreeSpaceBitmap) isItem() {}
 func (FreeSpaceInfo) isItem()   {}
 func (Inode) isItem()           {}
diff --git a/pkg/btrfs/internal/itemtype.go b/pkg/btrfs/internal/itemtype.go
index aa6e4f9..842f5b6 100644
--- a/pkg/btrfs/internal/itemtype.go
+++ b/pkg/btrfs/internal/itemtype.go
@@ -13,6 +13,7 @@ const (
 	DEV_ITEM_KEY             = ItemType(216)
 	DIR_INDEX_KEY            = ItemType(96)
 	DIR_ITEM_KEY             = ItemType(84)
+	EXTENT_DATA_KEY          = ItemType(108)
 	EXTENT_DATA_REF_KEY      = ItemType(178)
 	EXTENT_ITEM_KEY          = ItemType(168)
 	FREE_SPACE_BITMAP_KEY    = ItemType(200)
@@ -42,6 +43,7 @@ func (t ItemType) String() string {
 		DEV_ITEM_KEY:             "DEV_ITEM",
 		DIR_INDEX_KEY:            "DIR_INDEX",
 		DIR_ITEM_KEY:             "DIR_ITEM",
+		EXTENT_DATA_KEY:          "EXTENT_DATA",
 		EXTENT_DATA_REF_KEY:      "EXTENT_DATA_REF",
 		EXTENT_ITEM_KEY:          "EXTENT_ITEM",
 		FREE_SPACE_BITMAP_KEY:    "FREE_SPACE_BITMAP",