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|
package btrfs
import (
"fmt"
"os"
"lukeshu.com/btrfs-tools/pkg/util"
)
type Device struct {
*os.File
}
func (dev Device) Size() (PhysicalAddr, error) {
fi, err := dev.Stat()
if err != nil {
return 0, err
}
return PhysicalAddr(fi.Size()), nil
}
var superblockAddrs = []PhysicalAddr{
0x00_0001_0000, // 64KiB
0x00_0400_0000, // 64MiB
0x40_0000_0000, // 256GiB
}
func (dev *Device) ReadAt(dat []byte, paddr PhysicalAddr) (int, error) {
return dev.File.ReadAt(dat, int64(paddr))
}
func (dev *Device) Superblocks() ([]util.Ref[PhysicalAddr, Superblock], error) {
const superblockSize = 0x1000
sz, err := dev.Size()
if err != nil {
return nil, err
}
var ret []util.Ref[PhysicalAddr, Superblock]
for i, addr := range superblockAddrs {
if addr+superblockSize <= sz {
superblock := util.Ref[PhysicalAddr, Superblock]{
File: dev,
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
}
func (dev *Device) Superblock() (ret util.Ref[PhysicalAddr, Superblock], err error) {
sbs, err := dev.Superblocks()
if err != nil {
return ret, err
}
for i, sb := range sbs {
if err := sb.Data.ValidateChecksum(); err != nil {
return ret, fmt.Errorf("superblock %d: %w", i, err)
}
if i > 0 {
if !sb.Data.Equal(sbs[0].Data) {
return ret, fmt.Errorf("superblock %d and superblock %d disagree", 0, i)
}
}
}
return sbs[0], nil
}
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