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|
package btrfs
import (
"fmt"
"io"
"path/filepath"
"reflect"
"sort"
"sync"
"github.com/datawire/dlib/derror"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsitem"
"lukeshu.com/btrfs-tools/pkg/btrfs/btrfsvol"
"lukeshu.com/btrfs-tools/pkg/util"
)
type BareInode struct {
Inode ObjID
InodeItem *btrfsitem.Inode
Errs derror.MultiError
}
type FullInode struct {
BareInode
OtherItems []Item
}
type InodeRef struct {
Inode ObjID
btrfsitem.InodeRef
}
type Dir struct {
FullInode
DotDot *InodeRef
ChildrenByName map[string]btrfsitem.DirEntry
ChildrenByIndex map[uint64]btrfsitem.DirEntry
SV *Subvolume
}
type FileExtent struct {
OffsetWithinFile int64
btrfsitem.FileExtent
}
type File struct {
FullInode
Extents []FileExtent
SV *Subvolume
}
type Subvolume struct {
FS *FS
TreeID ObjID
rootOnce sync.Once
rootVal btrfsitem.Root
rootErr error
bareInodeCache util.LRUCache[ObjID, *BareInode]
fullInodeCache util.LRUCache[ObjID, *FullInode]
dirCache util.LRUCache[ObjID, *Dir]
fileCache util.LRUCache[ObjID, *File]
}
func (sv *Subvolume) init() {
sv.rootOnce.Do(func() {
sb, err := sv.FS.Superblock()
if err != nil {
sv.rootErr = err
return
}
root, err := sv.FS.TreeLookup(sb.Data.RootTree, Key{
ObjectID: sv.TreeID,
ItemType: btrfsitem.ROOT_ITEM_KEY,
Offset: 0,
})
if err != nil {
sv.rootErr = err
return
}
rootBody, ok := root.Body.(btrfsitem.Root)
if !ok {
sv.rootErr = fmt.Errorf("FS_TREE_ ROOT_ITEM has malformed body")
return
}
sv.rootVal = rootBody
})
}
func (sv *Subvolume) GetRootInode() (ObjID, error) {
sv.init()
return sv.rootVal.RootDirID, sv.rootErr
}
func (sv *Subvolume) GetFSTree() (btrfsvol.LogicalAddr, error) {
sv.init()
return sv.rootVal.ByteNr, sv.rootErr
}
func (sv *Subvolume) LoadBareInode(inode ObjID) (*BareInode, error) {
val := sv.bareInodeCache.GetOrElse(inode, func() (val *BareInode) {
val = &BareInode{
Inode: inode,
}
tree, err := sv.GetFSTree()
if err != nil {
val.Errs = append(val.Errs, err)
return
}
item, err := sv.FS.TreeLookup(tree, Key{
ObjectID: inode,
ItemType: btrfsitem.INODE_ITEM_KEY,
Offset: 0,
})
if err != nil {
val.Errs = append(val.Errs, err)
return
}
itemBody, ok := item.Body.(btrfsitem.Inode)
if !ok {
val.Errs = append(val.Errs, fmt.Errorf("malformed inode"))
return
}
val.InodeItem = &itemBody
return
})
if val.InodeItem == nil {
return nil, val.Errs
}
return val, nil
}
func (sv *Subvolume) LoadFullInode(inode ObjID) (*FullInode, error) {
val := sv.fullInodeCache.GetOrElse(inode, func() (val *FullInode) {
val = &FullInode{
BareInode: BareInode{
Inode: inode,
},
}
tree, err := sv.GetFSTree()
if err != nil {
val.Errs = append(val.Errs, err)
return
}
items, err := sv.FS.TreeSearchAll(tree, func(key Key) int {
return util.CmpUint(inode, key.ObjectID)
})
if err != nil {
val.Errs = append(val.Errs, err)
if len(items) == 0 {
return
}
}
for _, item := range items {
switch item.Head.Key.ItemType {
case btrfsitem.INODE_ITEM_KEY:
itemBody := item.Body.(btrfsitem.Inode)
if val.InodeItem != nil {
if !reflect.DeepEqual(itemBody, *val.InodeItem) {
val.Errs = append(val.Errs, fmt.Errorf("multiple inodes"))
}
continue
}
val.InodeItem = &itemBody
default:
val.OtherItems = append(val.OtherItems, item)
}
}
return
})
if val.InodeItem == nil && val.OtherItems == nil {
return nil, val.Errs
}
return val, nil
}
func (sv *Subvolume) LoadDir(inode ObjID) (*Dir, error) {
val := sv.dirCache.GetOrElse(inode, func() (val *Dir) {
val = new(Dir)
fullInode, err := sv.LoadFullInode(inode)
if err != nil {
val.Errs = append(val.Errs, err)
return
}
val.FullInode = *fullInode
val.SV = sv
val.populate()
return
})
if val.Inode == 0 {
return nil, val.Errs
}
return val, nil
}
func (ret *Dir) populate() {
ret.ChildrenByName = make(map[string]btrfsitem.DirEntry)
ret.ChildrenByIndex = make(map[uint64]btrfsitem.DirEntry)
for _, item := range ret.OtherItems {
switch item.Head.Key.ItemType {
case btrfsitem.INODE_REF_KEY:
ref := InodeRef{
Inode: ObjID(item.Head.Key.Offset),
InodeRef: item.Body.(btrfsitem.InodeRef),
}
if ret.DotDot != nil {
if !reflect.DeepEqual(ref, *ret.DotDot) {
ret.Errs = append(ret.Errs, fmt.Errorf("multiple INODE_REF items on a directory"))
}
continue
}
ret.DotDot = &ref
case btrfsitem.DIR_ITEM_KEY:
body := item.Body.(btrfsitem.DirEntries)
if len(body) != 1 {
ret.Errs = append(ret.Errs, fmt.Errorf("multiple direntries in single DIR_ITEM?"))
continue
}
for _, entry := range body {
namehash := btrfsitem.NameHash(entry.Name)
if namehash != item.Head.Key.Offset {
ret.Errs = append(ret.Errs, fmt.Errorf("direntry crc32c mismatch: key=%#x crc32c(%q)=%#x",
item.Head.Key.Offset, entry.Name, namehash))
continue
}
if other, exists := ret.ChildrenByName[string(entry.Name)]; exists {
if !reflect.DeepEqual(entry, other) {
ret.Errs = append(ret.Errs, fmt.Errorf("multiple instances of direntry name %q", entry.Name))
}
continue
}
ret.ChildrenByName[string(entry.Name)] = entry
}
case btrfsitem.DIR_INDEX_KEY:
index := item.Head.Key.Offset
body := item.Body.(btrfsitem.DirEntries)
if len(body) != 1 {
ret.Errs = append(ret.Errs, fmt.Errorf("multiple direntries in single DIR_INDEX?"))
continue
}
for _, entry := range body {
if other, exists := ret.ChildrenByIndex[index]; exists {
if !reflect.DeepEqual(entry, other) {
ret.Errs = append(ret.Errs, fmt.Errorf("multiple instances of direntry index %v", index))
}
continue
}
ret.ChildrenByIndex[index] = entry
}
//case btrfsitem.XATTR_ITEM_KEY:
default:
panic(fmt.Errorf("TODO: handle item type %v", item.Head.Key.ItemType))
}
}
entriesWithIndexes := make(map[string]struct{})
nextIndex := uint64(2)
for index, entry := range ret.ChildrenByIndex {
if index+1 > nextIndex {
nextIndex = index + 1
}
entriesWithIndexes[string(entry.Name)] = struct{}{}
if other, exists := ret.ChildrenByName[string(entry.Name)]; !exists {
ret.Errs = append(ret.Errs, fmt.Errorf("missing by-name direntry for %q", entry.Name))
ret.ChildrenByName[string(entry.Name)] = entry
} else if !reflect.DeepEqual(entry, other) {
ret.Errs = append(ret.Errs, fmt.Errorf("direntry index %v and direntry name %q disagree", index, entry.Name))
ret.ChildrenByName[string(entry.Name)] = entry
}
}
for _, name := range util.SortedMapKeys(ret.ChildrenByName) {
if _, exists := entriesWithIndexes[name]; !exists {
ret.Errs = append(ret.Errs, fmt.Errorf("missing by-index direntry for %q", name))
ret.ChildrenByIndex[nextIndex] = ret.ChildrenByName[name]
nextIndex++
}
}
return
}
func (dir *Dir) AbsPath() (string, error) {
rootInode, err := dir.SV.GetRootInode()
if err != nil {
return "", err
}
if rootInode == dir.Inode {
return "/", nil
}
if dir.DotDot == nil {
return "", fmt.Errorf("missing .. entry in dir inode %v", dir.Inode)
}
parent, err := dir.SV.LoadDir(dir.DotDot.Inode)
if err != nil {
return "", err
}
parentName, err := parent.AbsPath()
if err != nil {
return "", err
}
return filepath.Join(parentName, string(dir.DotDot.Name)), nil
}
func (sv *Subvolume) LoadFile(inode ObjID) (*File, error) {
val := sv.fileCache.GetOrElse(inode, func() (val *File) {
val = new(File)
fullInode, err := sv.LoadFullInode(inode)
if err != nil {
val.Errs = append(val.Errs, err)
return
}
val.FullInode = *fullInode
val.SV = sv
val.populate()
return
})
if val.Inode == 0 {
return nil, val.Errs
}
return val, nil
}
func (ret *File) populate() {
for _, item := range ret.OtherItems {
switch item.Head.Key.ItemType {
case btrfsitem.INODE_REF_KEY:
// TODO
case btrfsitem.EXTENT_DATA_KEY:
ret.Extents = append(ret.Extents, FileExtent{
OffsetWithinFile: int64(item.Head.Key.Offset),
FileExtent: item.Body.(btrfsitem.FileExtent),
})
default:
panic(fmt.Errorf("TODO: handle item type %v", item.Head.Key.ItemType))
}
}
// These should already be sorted, because of the nature of
// the btree; but this is a recovery tool for corrupt
// filesystems, so go ahead and ensure that it's sorted.
sort.Slice(ret.Extents, func(i, j int) bool {
return ret.Extents[i].OffsetWithinFile < ret.Extents[j].OffsetWithinFile
})
pos := int64(0)
for _, extent := range ret.Extents {
if extent.OffsetWithinFile != pos {
if extent.OffsetWithinFile > pos {
ret.Errs = append(ret.Errs, fmt.Errorf("extent gap from %v to %v",
pos, extent.OffsetWithinFile))
} else {
ret.Errs = append(ret.Errs, fmt.Errorf("extent overlap from %v to %v",
extent.OffsetWithinFile, pos))
}
}
size, err := extent.Size()
if err != nil {
ret.Errs = append(ret.Errs, fmt.Errorf("extent %v: %w", extent.OffsetWithinFile, err))
}
pos += size
}
if ret.InodeItem != nil && pos != ret.InodeItem.Size {
if ret.InodeItem.Size > pos {
ret.Errs = append(ret.Errs, fmt.Errorf("extent gap from %v to %v",
pos, ret.InodeItem.Size))
} else {
ret.Errs = append(ret.Errs, fmt.Errorf("extent mapped past end of file from %v to %v",
ret.InodeItem.Size, pos))
}
}
}
func (file *File) ReadAt(dat []byte, off int64) (int, error) {
// These stateles maybe-short-reads each do an O(n) extent
// lookup, so reading a file is O(n^2), but we expect n to be
// small, so whatev. Turn file.Extents it in to an rbtree if
// it becomes a problem.
done := 0
for done < len(dat) {
n, err := file.maybeShortReadAt(dat[done:], off+int64(done))
done += n
if err != nil {
return done, err
}
}
return done, nil
}
func (file *File) maybeShortReadAt(dat []byte, off int64) (int, error) {
for _, extent := range file.Extents {
extBeg := extent.OffsetWithinFile
if extBeg > off {
break
}
extLen, err := extent.Size()
if err != nil {
continue
}
extEnd := extBeg + extLen
if extEnd <= off {
continue
}
offsetWithinExt := off - extent.OffsetWithinFile
readSize := util.Min(int64(len(dat)), extLen-offsetWithinExt)
switch extent.Type {
case btrfsitem.FILE_EXTENT_INLINE:
return copy(dat, extent.BodyInline[offsetWithinExt:offsetWithinExt+readSize]), nil
case btrfsitem.FILE_EXTENT_REG, btrfsitem.FILE_EXTENT_PREALLOC:
return file.SV.FS.ReadAt(dat[:readSize],
extent.BodyExtent.DiskByteNr.
Add(extent.BodyExtent.Offset).
Add(btrfsvol.AddrDelta(offsetWithinExt)))
}
}
if file.InodeItem != nil && off >= file.InodeItem.Size {
return 0, io.EOF
}
return 0, fmt.Errorf("read: could not map position %v", off)
}
var _ io.ReaderAt = (*File)(nil)
|