diff options
Diffstat (limited to 'cmd')
| -rw-r--r-- | cmd/btrfs-dbg/main.go | 105 | ||||
| -rw-r--r-- | cmd/btrfs-dbg/types.go | 80 |
2 files changed, 185 insertions, 0 deletions
diff --git a/cmd/btrfs-dbg/main.go b/cmd/btrfs-dbg/main.go new file mode 100644 index 0000000..8758cd0 --- /dev/null +++ b/cmd/btrfs-dbg/main.go @@ -0,0 +1,105 @@ +package main + +import ( + "fmt" + "os" + + "lukeshu.com/btrfs-tools/pkg/binstruct" +) + +func main() { + if err := Main(os.Args[1]); err != nil { + fmt.Fprintf(os.Stderr, "%s: error: %v\n", os.Args[0], err) + os.Exit(1) + } +} + +func Main(imgfilename string) (err error) { + maybeSetErr := func(_err error) { + if _err != nil && err == nil { + err = _err + } + } + + fh, err := os.Open(imgfilename) + if err != nil { + return err + } + img := &Img{ + File: fh, + } + defer func() { + maybeSetErr(img.Close()) + }() + + superblocks, err := img.Superblocks() + if err != nil { + return err + } + fmt.Printf("%#v\n", superblocks[0]) + + return nil +} + +type Img struct { + *os.File +} + +func (img *Img) Size() (int64, error) { + fi, err := img.Stat() + if err != nil { + return 0, err + } + return fi.Size(), nil +} + +type Ref[T any] struct { + img *Img + addr int64 + data T +} + +func (r *Ref[T]) Read() error { + size, err := binstruct.Size(r.data) + if err != nil { + return err + } + buf := make([]byte, size) + if _, err := r.img.ReadAt(buf, r.addr); err != nil { + return err + } + return binstruct.Unmarshal(buf, &r.data) +} + +func (img *Img) Superblocks() ([]Ref[Superblock], error) { + const superblockSize = 0x1000 + + var superblockAddrs = []int64{ + 0x00_0001_0000, // 64KiB + 0x00_0400_0000, // 64MiB + 0x40_0000_0000, // 256GiB + } + + sz, err := img.Size() + if err != nil { + return nil, err + } + + var ret []Ref[Superblock] + for i, addr := range superblockAddrs { + if addr+superblockSize <= sz { + superblock := Ref[Superblock]{ + img: img, + addr: addr, + } + if err := superblock.Read(); err != nil { + return nil, fmt.Errorf("superblock %d: %w", i, err) + } + ret = append(ret, superblock) + } + } + if len(ret) == 0 { + return nil, fmt.Errorf("no superblocks") + } + return ret, nil +} diff --git a/cmd/btrfs-dbg/types.go b/cmd/btrfs-dbg/types.go new file mode 100644 index 0000000..33f78ba --- /dev/null +++ b/cmd/btrfs-dbg/types.go @@ -0,0 +1,80 @@ +package main + +import ( + "lukeshu.com/btrfs-tools/pkg/binstruct" +) + +type ( + PhysicalAddr int64 + LogicalAddr int64 + UUID [16]byte +) + +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"` + Self PhysicalAddr `bin:"off=30, siz=8, desc=physical address of this block (different for mirrors)"` + Flags uint64 `bin:"off=38, siz=8, desc=flags"` + Magic [8]byte `bin:"off=40, siz=8, desc=magic ('_BHRfS_M')"` + Generation uint64 `bin:"off=48, siz=8, desc=generation"` + + RootTree LogicalAddr `bin:"off=50, siz=8, desc=logical address of the root tree root"` + ChunkTree LogicalAddr `bin:"off=58, siz=8, desc=logical address of the chunk tree root"` + LogTree LogicalAddr `bin:"off=60, siz=8, desc=logical address of the log tree root"` + + LogRootTransID uint64 `bin:"off=68, siz=8, desc=log_root_transid"` + TotalBytes uint64 `bin:"off=70, siz=8, desc=total_bytes"` + BytesUsed uint64 `bin:"off=78, siz=8, desc=bytes_used"` + RootDirObjectID uint64 `bin:"off=80, siz=8, desc=root_dir_objectid (usually 6)"` + NumDevices uint64 `bin:"off=88, siz=8, desc=num_devices"` + + SectorSize uint32 `bin:"off=90, siz=4, desc=sectorsize"` + NodeSize uint32 `bin:"off=94, siz=4, desc=nodesize"` + LeafSize uint32 `bin:"off=98, siz=4, desc=leafsize"` + StripeSize uint32 `bin:"off=9c, siz=4, desc=stripesize"` + SysChunkArraySize uint32 `bin:"off=a0, siz=4, desc=sys_chunk_array_size"` + + ChunkRootGeneration uint64 `bin:"off=a4, siz=8, desc=chunk_root_generation"` + CompatFlags uint64 `bin:"off=ac, siz=8, desc=compat_flags"` + CompatROFlags uint64 `bin:"off=b4, siz=8, desc=compat_ro_flags - only implementations that support the flags can write to the filesystem"` + IncompatFlags uint64 `bin:"off=bc, siz=8, desc=incompat_flags - only implementations that support the flags can use the filesystem"` + ChecksumType uint16 `bin:"off=c4, siz=2, desc=csum_type - Btrfs currently uses the CRC32c little-endian hash function with seed -1."` + + RootLevel uint8 `bin:"off=c6, siz=1, desc=root_level"` + ChunkLevel uint8 `bin:"off=c7, siz=1, desc=chunk_root_level"` + LogLevel uint8 `bin:"off=c8, siz=1, desc=log_root_level"` + + DevItem DevItem `bin:"off=c9, siz=62, desc=DEV_ITEM data for this device"` + 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"` + + binstruct.End `bin:"off=1000"` +} + +type DevItem struct { + DeviceID uint64 `bin:"off=0, siz=8, desc=device id"` + + NumBytes uint64 `bin:"off=8, siz=8, desc=number of bytes"` + NumBytesUsed uint64 `bin:"off=10, siz=8, desc=number of bytes used"` + + IOOptimalAlign uint32 `bin:"off=18, siz=4, desc=optimal I/O align"` + IOOptimalWidth uint32 `bin:"off=1c, siz=4, desc=optimal I/O width"` + IOMinSize uint32 `bin:"off=20, siz=4, desc=minimal I/O size (sector size)"` + + Type uint64 `bin:"off=24, siz=8, desc=type"` + Generation uint64 `bin:"off=2c, siz=8, desc=generation"` + StartOffset uint64 `bin:"off=34, siz=8, desc=start offset"` + DevGroup uint32 `bin:"off=3c, siz=4, desc=dev group"` + SeekSpeed uint8 `bin:"off=40, siz=1, desc=seek speed"` + Bandwidth uint8 `bin:"off=41, siz=1, desc=bandwidth"` + + DevUUID UUID `bin:"off=42, siz=10, desc=device UUID"` + FSUUID UUID `bin:"off=52, siz=10, desc=FS UUID"` + + binstruct.End `bin:"off=62"` +} |