From 3825cf60fd652f22acc438d50028701d27a7402d Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@lukeshu.com>
Date: Wed, 1 Jun 2022 01:27:19 -0600
Subject: wow

---
 pkg/btrfs/btrfsitem/item_chunk.go | 62 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
 create mode 100644 pkg/btrfs/btrfsitem/item_chunk.go

(limited to 'pkg/btrfs/btrfsitem/item_chunk.go')

diff --git a/pkg/btrfs/btrfsitem/item_chunk.go b/pkg/btrfs/btrfsitem/item_chunk.go
new file mode 100644
index 0000000..41706c3
--- /dev/null
+++ b/pkg/btrfs/btrfsitem/item_chunk.go
@@ -0,0 +1,62 @@
+package btrfsitem
+
+import (
+	"lukeshu.com/btrfs-tools/pkg/binstruct"
+	"lukeshu.com/btrfs-tools/pkg/btrfs/btrfstyp"
+)
+
+type Chunk struct { // CHUNK_ITEM=228
+	// Maps logical address to physical.
+	Size           uint64         `bin:"off=0x0,  siz=0x8"` // size of chunk (bytes)
+	Owner          btrfstyp.ObjID `bin:"off=0x8,  siz=0x8"` // root referencing this chunk (2)
+	StripeLen      uint64         `bin:"off=0x10, siz=0x8"` // stripe length
+	Type           uint64         `bin:"off=0x18, siz=0x8"` // type (same as flags for block group?)
+	IOOptimalAlign uint32         `bin:"off=0x20, siz=0x4"` // optimal io alignment
+	IOOptimalWidth uint32         `bin:"off=0x24, siz=0x4"` // optimal io width
+	IoMinSize      uint32         `bin:"off=0x28, siz=0x4"` // minimal io size (sector size)
+	NumStripes     uint16         `bin:"off=0x2c, siz=0x2"` // number of stripes
+	SubStripes     uint16         `bin:"off=0x2e, siz=0x2"` // sub stripes
+	binstruct.End  `bin:"off=0x30"`
+	Stripes        []ChunkStripe `bin:"-"`
+}
+
+type ChunkStripe struct {
+	// Stripes follow (for each number of stripes):
+	DeviceID      btrfstyp.ObjID `bin:"off=0,  siz=8"`  // device ID
+	Offset        uint64         `bin:"off=8,  siz=8"`  // offset
+	DeviceUUID    btrfstyp.UUID  `bin:"off=10, siz=10"` // device UUID
+	binstruct.End `bin:"off=20"`
+}
+
+func (chunk *Chunk) UnmarshalBinary(dat []byte) (int, error) {
+	n, err := binstruct.UnmarshalWithoutInterface(dat, chunk)
+	if err != nil {
+		return n, err
+	}
+	for i := 0; i < int(chunk.NumStripes); i++ {
+		var stripe ChunkStripe
+		_n, err := binstruct.Unmarshal(dat[n:], &stripe)
+		n += _n
+		if err != nil {
+			return n, err
+		}
+		chunk.Stripes = append(chunk.Stripes, stripe)
+	}
+	return n, nil
+}
+
+func (chunk Chunk) MarshalBinary() ([]byte, error) {
+	chunk.NumStripes = uint16(len(chunk.Stripes))
+	ret, err := binstruct.MarshalWithoutInterface(chunk)
+	if err != nil {
+		return ret, err
+	}
+	for _, stripe := range chunk.Stripes {
+		_ret, err := binstruct.Marshal(stripe)
+		ret = append(ret, _ret...)
+		if err != nil {
+			return ret, err
+		}
+	}
+	return ret, nil
+}
-- 
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