more

6 files changed, 76 insertions, 17 deletions

diff --git a/cmd/btrfs-dbg/main.go b/cmd/btrfs-dbg/main.go
index 8758cd0..d6c9c68 100644
--- a/cmd/btrfs-dbg/main.go
+++ b/cmd/btrfs-dbg/main.go
@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/davecgh/go-spew/spew"
+
 	"lukeshu.com/btrfs-tools/pkg/binstruct"
 )
 
@@ -36,7 +38,11 @@ func Main(imgfilename string) (err error) {
 	if err != nil {
 		return err
 	}
-	fmt.Printf("%#v\n", superblocks[0])
+
+	spew := spew.NewDefaultConfig()
+	spew.DisablePointerAddresses = true
+
+	spew.Dump(superblocks[0].data)
 
 	return nil
 }
diff --git a/cmd/btrfs-dbg/types.go b/cmd/btrfs-dbg/types.go
index 33f78ba..699f1a2 100644
--- a/cmd/btrfs-dbg/types.go
+++ b/cmd/btrfs-dbg/types.go
@@ -1,15 +1,30 @@
 package main
 
 import (
+	"encoding/hex"
+	"strings"
+
 	"lukeshu.com/btrfs-tools/pkg/binstruct"
 )
 
 type (
 	PhysicalAddr int64
 	LogicalAddr  int64
+	ObjID        int64
 	UUID         [16]byte
 )
 
+func (uuid UUID) String() string {
+	str := hex.EncodeToString(uuid[:])
+	return strings.Join([]string{
+		str[:8],
+		str[8:12],
+		str[12:16],
+		str[16:20],
+		str[20:32],
+	}, "-")
+}
+
 type Superblock struct {
 	Checksum   [0x20]byte   `bin:"off=0,  siz=20, desc=Checksum of everything past this field (from 20 to 1000)"`
 	FSUUID     UUID         `bin:"off=20, siz=10, desc=FS UUID"`
@@ -48,10 +63,13 @@ type Superblock struct {
 	Label              [0x100]byte `bin:"off=12b, siz=100, desc=label (may not contain '/' or '\\')"`
 	CacheGeneration    uint64      `bin:"off=22b, siz=8,   desc=cache_generation"`
 	UUIDTreeGeneration uint64      `bin:"off=233, siz=8,   desc=uuid_tree_generation"`
-	Reserved           [0xf0]byte  `bin:"off=23b, siz=f0,  desc=reserved /* future expansion */"`
-	SysChunkArray      [0x800]byte `bin:"off=32b, siz=800, desc=sys_chunk_array:(n bytes valid) Contains (KEY . CHUNK_ITEM) pairs for all SYSTEM chunks. This is needed to bootstrap the mapping from logical addresses to physical. "`
-	SuperRoots         [0x2a0]byte `bin:"off=b2b, siz=2a0, desc=Contain super_roots (4 btrfs_root_backup)"`
-	Unused             [0x235]byte `bin:"off=dcb, siz=235, desc=current unused"`
+
+	Reserved [0xf0]byte `bin:"off=23b, siz=f0,  desc=reserved /* future expansion */"`
+
+	TODOSysChunkArray [0x800]byte `bin:"off=32b, siz=800, desc=sys_chunk_array:(n bytes valid) Contains (KEY . CHUNK_ITEM) pairs for all SYSTEM chunks. This is needed to bootstrap the mapping from logical addresses to physical. "`
+	TODOSuperRoots    [0x2a0]byte `bin:"off=b2b, siz=2a0, desc=Contain super_roots (4 btrfs_root_backup)"`
+
+	Unused [0x235]byte `bin:"off=dcb, siz=235, desc=current unused"`
 
 	binstruct.End `bin:"off=1000"`
 }
@@ -78,3 +96,25 @@ type DevItem struct {
 
 	binstruct.End `bin:"off=62"`
 }
+
+type ChunkItem struct {
+	// Maps logical address to physical.
+	Size           uint64 `bin:"off=0,  siz=8, desc=size of chunk (bytes)"`
+	Root           ObjID  `bin:"off=8,  siz=8, desc=root referencing this chunk (2)"`
+	StripeLen      uint64 `bin:"off=10, siz=8, desc=stripe length"`
+	Type           uint64 `bin:"off=18, siz=8, desc=type (same as flags for block group?)"`
+	IOOptimalAlign uint32 `bin:"off=20, siz=4, desc=optimal io alignment"`
+	IOOptimalWidth uint32 `bin:"off=24, siz=4, desc=optimal io width"`
+	IoMinSize      uint32 `bin:"off=28, siz=4, desc=minimal io size (sector size)"`
+	NumStripes     uint16 `bin:"off=2c, siz=2, desc=number of stripes"`
+	SubStripes     uint16 `bin:"off=2e, siz=2, desc=sub stripes"`
+	binstruct.End  `bin:"off=30"`
+}
+
+type ChunkItemStripe struct {
+	// Stripes follow (for each number of stripes):
+	DeviceID      ObjID  `bin:"off=0,  siz=8,  desc=device id"`
+	Offset        uint64 `bin:"off=8,  siz=8,  desc=offset"`
+	DeviceUUID    UUID   `bin:"off=10, siz=10, desc=device UUID"`
+	binstruct.End `bin:"off=20"`
+}
diff --git a/go.mod b/go.mod
index be29d20..28e854c 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,12 @@ module lukeshu.com/btrfs-tools
 
 go 1.18
 
-require github.com/stretchr/testify v1.7.1
+require (
+	github.com/davecgh/go-spew v1.1.0
+	github.com/stretchr/testify v1.7.1
+)
+
+require (
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c // indirect
+)
diff --git a/pkg/binstruct/l1.go b/pkg/binstruct/l1.go
index c535d2e..e76e7d0 100644
--- a/pkg/binstruct/l1.go
+++ b/pkg/binstruct/l1.go
@@ -136,10 +136,10 @@ func genHandler(typ reflect.Type) (handler, error) {
 		}
 		return primitive{
 			unmarshal: func(dat []byte) interface{} {
-				val := reflect.Zero(typ)
+				val := reflect.New(typ).Elem()
 				for i := 0; i < typ.Len(); i++ {
-					fmt.Printf("%v[%d]: %v\n", typ, i, val.Index(i))
-					val.Index(i).Set(reflect.ValueOf(inner.Unmarshal(dat[i*int(inner.Size()):])))
+					fieldVal := inner.Unmarshal(dat[i*int(inner.Size()):])
+					val.Index(i).Set(reflect.ValueOf(fieldVal).Convert(typ.Elem()))
 				}
 				return val.Interface()
 			},
diff --git a/pkg/binstruct/l2.go b/pkg/binstruct/l2.go
index 005d686..32aa313 100644
--- a/pkg/binstruct/l2.go
+++ b/pkg/binstruct/l2.go
@@ -16,18 +16,20 @@ type structHandler struct {
 }
 
 type structField struct {
+	typ reflect.Type
 	tag
 	handler
 	name string
 }
 
 func (sh structHandler) Unmarshal(dat []byte) interface{} {
-	val := reflect.Zero(sh.typ)
+	val := reflect.New(sh.typ).Elem()
 	for i, field := range sh.fields {
 		if field.skip {
 			continue
 		}
-		val.Field(i).Set(reflect.ValueOf(field.Unmarshal(dat[field.off:])))
+		fieldVal := field.Unmarshal(dat[field.off:])
+		val.Field(i).Set(reflect.ValueOf(fieldVal).Convert(field.typ))
 	}
 	return val.Interface()
 }
@@ -96,6 +98,7 @@ func genStructHandler(structInfo reflect.Type) (handler, error) {
 		curOffset += fieldTag.siz
 
 		ret.fields = append(ret.fields, structField{
+			typ:     fieldInfo.Type,
 			tag:     fieldTag,
 			handler: fieldHandler,
 			name:    fieldInfo.Name,
diff --git a/pkg/binstruct/l3.go b/pkg/binstruct/l3.go
index f9fb8b1..1ccaaf0 100644
--- a/pkg/binstruct/l3.go
+++ b/pkg/binstruct/l3.go
@@ -21,12 +21,14 @@ func getHandler(typ reflect.Type) (handler, error) {
 	return h, nil
 }
 
-func Unmarshal(dat []byte, dst interface{}) error {
-	_dst := reflect.ValueOf(dst)
-	if _dst.Kind() != reflect.Ptr {
-		return fmt.Errorf("not a pointer: %v", _dst.Type())
+func Unmarshal(dat []byte, dstPtr interface{}) error {
+	_dstPtr := reflect.ValueOf(dstPtr)
+	if _dstPtr.Kind() != reflect.Ptr {
+		return fmt.Errorf("not a pointer: %v", _dstPtr.Type())
 	}
-	handler, err := getHandler(_dst.Type().Elem())
+
+	dst := _dstPtr.Elem()
+	handler, err := getHandler(dst.Type())
 	if err != nil {
 		return err
 	}
@@ -35,7 +37,7 @@ func Unmarshal(dat []byte, dst interface{}) error {
 			handler.Size(), len(dat))
 	}
 	val := handler.Unmarshal(dat[:handler.Size()])
-	_dst.Elem().Set(reflect.ValueOf(val))
+	dst.Set(reflect.ValueOf(val).Convert(dst.Type()))
 	return nil
 }