restic/internal/restorer/restorer.go

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package restorer
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import (
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"context"
"os"
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"path/filepath"
"sync/atomic"
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"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/fs"
"github.com/restic/restic/internal/restic"
"golang.org/x/sync/errgroup"
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)
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// Restorer is used to restore a snapshot to a directory.
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type Restorer struct {
repo restic.Repository
sn *restic.Snapshot
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Error func(location string, err error) error
SelectFilter func(item string, dstpath string, node *restic.Node) (selectedForRestore bool, childMayBeSelected bool)
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}
var restorerAbortOnAllErrors = func(location string, err error) error { return err }
// NewRestorer creates a restorer preloaded with the content from the snapshot id.
func NewRestorer(ctx context.Context, repo restic.Repository, id restic.ID) (*Restorer, error) {
r := &Restorer{
repo: repo,
Error: restorerAbortOnAllErrors,
SelectFilter: func(string, string, *restic.Node) (bool, bool) { return true, true },
}
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var err error
r.sn, err = restic.LoadSnapshot(ctx, repo, id)
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if err != nil {
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return nil, err
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}
return r, nil
}
type treeVisitor struct {
enterDir func(node *restic.Node, target, location string) error
visitNode func(node *restic.Node, target, location string) error
leaveDir func(node *restic.Node, target, location string) error
}
// traverseTree traverses a tree from the repo and calls treeVisitor.
// target is the path in the file system, location within the snapshot.
func (res *Restorer) traverseTree(ctx context.Context, target, location string, treeID restic.ID, visitor treeVisitor) (hasRestored bool, err error) {
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debug.Log("%v %v %v", target, location, treeID)
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tree, err := res.repo.LoadTree(ctx, treeID)
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if err != nil {
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debug.Log("error loading tree %v: %v", treeID, err)
return hasRestored, res.Error(location, err)
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}
for _, node := range tree.Nodes {
// ensure that the node name does not contain anything that refers to a
// top-level directory.
nodeName := filepath.Base(filepath.Join(string(filepath.Separator), node.Name))
if nodeName != node.Name {
debug.Log("node %q has invalid name %q", node.Name, nodeName)
err := res.Error(location, errors.Errorf("invalid child node name %s", node.Name))
if err != nil {
return hasRestored, err
}
continue
}
nodeTarget := filepath.Join(target, nodeName)
nodeLocation := filepath.Join(location, nodeName)
if target == nodeTarget || !fs.HasPathPrefix(target, nodeTarget) {
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debug.Log("target: %v %v", target, nodeTarget)
debug.Log("node %q has invalid target path %q", node.Name, nodeTarget)
err := res.Error(nodeLocation, errors.New("node has invalid path"))
if err != nil {
return hasRestored, err
}
continue
}
// sockets cannot be restored
if node.Type == "socket" {
continue
}
selectedForRestore, childMayBeSelected := res.SelectFilter(nodeLocation, nodeTarget, node)
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debug.Log("SelectFilter returned %v %v for %q", selectedForRestore, childMayBeSelected, nodeLocation)
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if selectedForRestore {
hasRestored = true
}
sanitizeError := func(err error) error {
switch err {
case nil, context.Canceled, context.DeadlineExceeded:
// Context errors are permanent.
return err
default:
return res.Error(nodeLocation, err)
}
}
if node.Type == "dir" {
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if node.Subtree == nil {
return hasRestored, errors.Errorf("Dir without subtree in tree %v", treeID.Str())
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}
if selectedForRestore && visitor.enterDir != nil {
err = sanitizeError(visitor.enterDir(node, nodeTarget, nodeLocation))
if err != nil {
return hasRestored, err
}
}
// keep track of restored child status
// so metadata of the current directory are restored on leaveDir
childHasRestored := false
if childMayBeSelected {
childHasRestored, err = res.traverseTree(ctx, nodeTarget, nodeLocation, *node.Subtree, visitor)
err = sanitizeError(err)
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if err != nil {
return hasRestored, err
}
// inform the parent directory to restore parent metadata on leaveDir if needed
if childHasRestored {
hasRestored = true
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}
}
// metadata need to be restore when leaving the directory in both cases
// selected for restore or any child of any subtree have been restored
if (selectedForRestore || childHasRestored) && visitor.leaveDir != nil {
err = sanitizeError(visitor.leaveDir(node, nodeTarget, nodeLocation))
if err != nil {
return hasRestored, err
}
}
continue
}
if selectedForRestore {
err = sanitizeError(visitor.visitNode(node, nodeTarget, nodeLocation))
if err != nil {
return hasRestored, err
}
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}
}
return hasRestored, nil
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}
func (res *Restorer) restoreNodeTo(ctx context.Context, node *restic.Node, target, location string) error {
debug.Log("restoreNode %v %v %v", node.Name, target, location)
err := node.CreateAt(ctx, target, res.repo)
if err != nil {
debug.Log("node.CreateAt(%s) error %v", target, err)
}
if err == nil {
err = res.restoreNodeMetadataTo(node, target, location)
}
return err
}
func (res *Restorer) restoreNodeMetadataTo(node *restic.Node, target, location string) error {
debug.Log("restoreNodeMetadata %v %v %v", node.Name, target, location)
err := node.RestoreMetadata(target)
if err != nil {
debug.Log("node.RestoreMetadata(%s) error %v", target, err)
}
return err
}
func (res *Restorer) restoreHardlinkAt(node *restic.Node, target, path, location string) error {
if err := fs.Remove(path); !os.IsNotExist(err) {
return errors.Wrap(err, "RemoveCreateHardlink")
}
err := fs.Link(target, path)
if err != nil {
return errors.Wrap(err, "CreateHardlink")
}
// TODO investigate if hardlinks have separate metadata on any supported system
return res.restoreNodeMetadataTo(node, path, location)
}
func (res *Restorer) restoreEmptyFileAt(node *restic.Node, target, location string) error {
wr, err := os.OpenFile(target, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0600)
if err != nil {
return err
}
err = wr.Close()
if err != nil {
return err
}
return res.restoreNodeMetadataTo(node, target, location)
}
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// RestoreTo creates the directories and files in the snapshot below dst.
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// Before an item is created, res.Filter is called.
func (res *Restorer) RestoreTo(ctx context.Context, dst string) error {
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var err error
if !filepath.IsAbs(dst) {
dst, err = filepath.Abs(dst)
if err != nil {
return errors.Wrap(err, "Abs")
}
}
idx := restic.NewHardlinkIndex()
filerestorer := newFileRestorer(dst, res.repo.Backend().Load, res.repo.Key(), res.repo.Index().Lookup, res.repo.Connections())
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filerestorer.Error = res.Error
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debug.Log("first pass for %q", dst)
// first tree pass: create directories and collect all files to restore
_, err = res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
enterDir: func(node *restic.Node, target, location string) error {
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debug.Log("first pass, enterDir: mkdir %q, leaveDir should restore metadata", location)
// create dir with default permissions
// #leaveDir restores dir metadata after visiting all children
return fs.MkdirAll(target, 0700)
},
visitNode: func(node *restic.Node, target, location string) error {
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debug.Log("first pass, visitNode: mkdir %q, leaveDir on second pass should restore metadata", location)
// create parent dir with default permissions
// second pass #leaveDir restores dir metadata after visiting/restoring all children
err := fs.MkdirAll(filepath.Dir(target), 0700)
if err != nil {
return err
}
if node.Type != "file" {
return nil
}
if node.Size == 0 {
return nil // deal with empty files later
}
if node.Links > 1 {
if idx.Has(node.Inode, node.DeviceID) {
return nil
}
idx.Add(node.Inode, node.DeviceID, location)
}
filerestorer.addFile(location, node.Content, int64(node.Size))
return nil
},
})
if err != nil {
return err
}
err = filerestorer.restoreFiles(ctx)
if err != nil {
return err
}
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debug.Log("second pass for %q", dst)
// second tree pass: restore special files and filesystem metadata
_, err = res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
visitNode: func(node *restic.Node, target, location string) error {
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debug.Log("second pass, visitNode: restore node %q", location)
if node.Type != "file" {
return res.restoreNodeTo(ctx, node, target, location)
}
// create empty files, but not hardlinks to empty files
if node.Size == 0 && (node.Links < 2 || !idx.Has(node.Inode, node.DeviceID)) {
if node.Links > 1 {
idx.Add(node.Inode, node.DeviceID, location)
}
return res.restoreEmptyFileAt(node, target, location)
}
if idx.Has(node.Inode, node.DeviceID) && idx.GetFilename(node.Inode, node.DeviceID) != location {
return res.restoreHardlinkAt(node, filerestorer.targetPath(idx.GetFilename(node.Inode, node.DeviceID)), target, location)
}
return res.restoreNodeMetadataTo(node, target, location)
},
leaveDir: res.restoreNodeMetadataTo,
})
return err
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}
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// Snapshot returns the snapshot this restorer is configured to use.
func (res *Restorer) Snapshot() *restic.Snapshot {
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return res.sn
}
// Number of workers in VerifyFiles.
const nVerifyWorkers = 8
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// VerifyFiles checks whether all regular files in the snapshot res.sn
// have been successfully written to dst. It stops when it encounters an
// error. It returns that error and the number of files it has successfully
// verified.
func (res *Restorer) VerifyFiles(ctx context.Context, dst string) (int, error) {
type mustCheck struct {
node *restic.Node
path string
}
var (
nchecked uint64
work = make(chan mustCheck, 2*nVerifyWorkers)
)
g, ctx := errgroup.WithContext(ctx)
// Traverse tree and send jobs to work.
g.Go(func() error {
defer close(work)
_, err := res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
visitNode: func(node *restic.Node, target, location string) error {
if node.Type != "file" {
return nil
}
select {
case <-ctx.Done():
return ctx.Err()
case work <- mustCheck{node, target}:
return nil
}
},
})
return err
})
for i := 0; i < nVerifyWorkers; i++ {
g.Go(func() (err error) {
var buf []byte
for job := range work {
buf, err = res.verifyFile(job.path, job.node, buf)
if err != nil {
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err = res.Error(job.path, err)
}
if err != nil || ctx.Err() != nil {
break
}
atomic.AddUint64(&nchecked, 1)
}
return err
})
}
return int(nchecked), g.Wait()
}
// Verify that the file target has the contents of node.
//
// buf and the first return value are scratch space, passed around for reuse.
// Reusing buffers prevents the verifier goroutines allocating all of RAM and
// flushing the filesystem cache (at least on Linux).
func (res *Restorer) verifyFile(target string, node *restic.Node, buf []byte) ([]byte, error) {
f, err := os.Open(target)
if err != nil {
return buf, err
}
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defer func() {
_ = f.Close()
}()
fi, err := f.Stat()
switch {
case err != nil:
return buf, err
case int64(node.Size) != fi.Size():
return buf, errors.Errorf("Invalid file size for %s: expected %d, got %d",
target, node.Size, fi.Size())
}
var offset int64
for _, blobID := range node.Content {
length, found := res.repo.LookupBlobSize(blobID, restic.DataBlob)
if !found {
return buf, errors.Errorf("Unable to fetch blob %s", blobID)
}
if length > uint(cap(buf)) {
buf = make([]byte, 2*length)
}
buf = buf[:length]
_, err = f.ReadAt(buf, offset)
if err != nil {
return buf, err
}
if !blobID.Equal(restic.Hash(buf)) {
return buf, errors.Errorf(
"Unexpected content in %s, starting at offset %d",
target, offset)
}
offset += int64(length)
}
return buf, nil
}