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package btrfsmisc
import (
"fmt"
"lukeshu.com/btrfs-tools/pkg/binstruct"
"lukeshu.com/btrfs-tools/pkg/btrfs"
"lukeshu.com/btrfs-tools/pkg/util"
)
// ScanForNodes mimics btrfs-progs
// cmds/rescue-chunk-recover.c:scan_one_device(), except it doesn't do
// anything but log when it finds a node.
func ScanForNodes(dev *btrfs.Device, sb btrfs.Superblock) error {
devSize, err := dev.Size()
if err != nil {
return err
}
if sb.NodeSize < sb.SectorSize {
return fmt.Errorf("node_size(%d) < sector_size(%d)",
sb.NodeSize, sb.SectorSize)
}
nodeBuf := make([]byte, sb.NodeSize)
for pos := btrfs.PhysicalAddr(0); pos+btrfs.PhysicalAddr(sb.SectorSize) < devSize; pos += btrfs.PhysicalAddr(sb.SectorSize) {
if util.InSlice(pos, btrfs.SuperblockAddrs) {
fmt.Printf("sector@%d is a superblock\n", pos)
continue
}
if _, err := dev.ReadAt(nodeBuf, pos); err != nil {
return fmt.Errorf("sector@%d: %w", pos, err)
}
var nodeHeader btrfs.NodeHeader
if _, err := binstruct.Unmarshal(nodeBuf, &nodeHeader); err != nil {
return fmt.Errorf("sector@%d: %w", pos, err)
}
if !nodeHeader.MetadataUUID.Equal(sb.EffectiveMetadataUUID()) {
//fmt.Printf("sector@%d does not look like a node\n", pos)
continue
}
if !nodeHeader.Checksum.Equal(btrfs.CRC32c(nodeBuf[0x20:])) {
fmt.Printf("sector@%d looks like a node but is corrupt (checksum doesn't match)\n", pos)
continue
}
fmt.Printf("node@%d: physical_addr=0x%0X logical_addr=0x%0X generation=%d owner=%v level=%d\n",
pos, pos, nodeHeader.Addr, nodeHeader.Generation, nodeHeader.Owner, nodeHeader.Level)
pos += btrfs.PhysicalAddr(sb.NodeSize) - btrfs.PhysicalAddr(sb.SectorSize)
}
return nil
}
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