From 27401b6ea459921a6152ab1744da1618358465f4 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Sun, 10 Jul 2022 13:18:30 -0600
Subject: Rename the module, mv pkg lib

---
 lib/btrfs/btrfsitem/item_extent.go | 165 +++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)
 create mode 100644 lib/btrfs/btrfsitem/item_extent.go

(limited to 'lib/btrfs/btrfsitem/item_extent.go')

diff --git a/lib/btrfs/btrfsitem/item_extent.go b/lib/btrfs/btrfsitem/item_extent.go
new file mode 100644
index 0000000..9a9ea55
--- /dev/null
+++ b/lib/btrfs/btrfsitem/item_extent.go
@@ -0,0 +1,165 @@
+package btrfsitem
+
+import (
+	"fmt"
+
+	"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
+	"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/internal"
+	"git.lukeshu.com/btrfs-progs-ng/lib/util"
+)
+
+type Extent struct { // EXTENT_ITEM=168
+	Head ExtentHeader
+	Info TreeBlockInfo // only if .Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK)
+	Refs []ExtentInlineRef
+}
+
+func (o *Extent) UnmarshalBinary(dat []byte) (int, error) {
+	n, err := binstruct.Unmarshal(dat, &o.Head)
+	if err != nil {
+		return n, err
+	}
+	if o.Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK) {
+		_n, err := binstruct.Unmarshal(dat[n:], &o.Info)
+		n += _n
+		if err != nil {
+			return n, err
+		}
+	}
+	o.Refs = nil
+	for n < len(dat) {
+		var ref ExtentInlineRef
+		_n, err := binstruct.Unmarshal(dat[n:], &ref)
+		n += _n
+		o.Refs = append(o.Refs, ref)
+		if err != nil {
+			return n, err
+		}
+	}
+	return n, nil
+}
+
+func (o Extent) MarshalBinary() ([]byte, error) {
+	dat, err := binstruct.Marshal(o.Head)
+	if err != nil {
+		return dat, err
+	}
+	if o.Head.Flags.Has(EXTENT_FLAG_TREE_BLOCK) {
+		bs, err := binstruct.Marshal(o.Info)
+		dat = append(dat, bs...)
+		if err != nil {
+			return dat, err
+		}
+	}
+	for _, ref := range o.Refs {
+		bs, err := binstruct.Marshal(ref)
+		dat = append(dat, bs...)
+		if err != nil {
+			return dat, err
+		}
+	}
+	return dat, nil
+}
+
+type ExtentHeader struct {
+	Refs          int64               `bin:"off=0, siz=8"`
+	Generation    internal.Generation `bin:"off=8, siz=8"`
+	Flags         ExtentFlags         `bin:"off=16, siz=8"`
+	binstruct.End `bin:"off=24"`
+}
+
+type TreeBlockInfo struct {
+	Key           internal.Key `bin:"off=0, siz=0x11"`
+	Level         uint8        `bin:"off=0x11, siz=0x8"`
+	binstruct.End `bin:"off=0x19"`
+}
+
+type ExtentFlags uint64
+
+const (
+	EXTENT_FLAG_DATA = ExtentFlags(1 << iota)
+	EXTENT_FLAG_TREE_BLOCK
+)
+
+var extentFlagNames = []string{
+	"DATA",
+	"TREE_BLOCK",
+}
+
+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   // 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) {
+	o.Type = Type(dat[0])
+	n := 1
+	switch o.Type {
+	case TREE_BLOCK_REF_KEY, SHARED_BLOCK_REF_KEY:
+		_n, err := binstruct.Unmarshal(dat[n:], &o.Offset)
+		n += _n
+		if err != nil {
+			return n, err
+		}
+	case EXTENT_DATA_REF_KEY:
+		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 += _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 := []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
+}
-- 
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