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restic/internal/restorer/restorer.go
2020-09-07 21:41:47 +02:00

340 lines
9.4 KiB
Go

package restorer
import (
"context"
"os"
"path/filepath"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/fs"
"github.com/restic/restic/internal/restic"
)
// Restorer is used to restore a snapshot to a directory.
type Restorer struct {
repo restic.Repository
sn *restic.Snapshot
Error func(location string, err error) error
SelectFilter func(item string, dstpath string, node *restic.Node) (selectedForRestore bool, childMayBeSelected bool)
}
var restorerAbortOnAllErrors = func(location string, err error) error { return err }
// NewRestorer creates a restorer preloaded with the content from the snapshot id.
func NewRestorer(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 },
}
var err error
r.sn, err = restic.LoadSnapshot(context.TODO(), repo, id)
if err != nil {
return nil, err
}
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) error {
debug.Log("%v %v %v", target, location, treeID)
tree, err := res.repo.LoadTree(ctx, treeID)
if err != nil {
debug.Log("error loading tree %v: %v", treeID, err)
return res.Error(location, err)
}
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 err
}
continue
}
nodeTarget := filepath.Join(target, nodeName)
nodeLocation := filepath.Join(location, nodeName)
if target == nodeTarget || !fs.HasPathPrefix(target, nodeTarget) {
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 err
}
continue
}
// sockets cannot be restored
if node.Type == "socket" {
continue
}
selectedForRestore, childMayBeSelected := res.SelectFilter(nodeLocation, nodeTarget, node)
debug.Log("SelectFilter returned %v %v", selectedForRestore, childMayBeSelected)
sanitizeError := func(err error) error {
if err != nil {
err = res.Error(nodeLocation, err)
}
return err
}
if node.Type == "dir" {
if node.Subtree == nil {
return errors.Errorf("Dir without subtree in tree %v", treeID.Str())
}
if selectedForRestore {
err = sanitizeError(visitor.enterDir(node, nodeTarget, nodeLocation))
if err != nil {
return err
}
}
if childMayBeSelected {
err = sanitizeError(res.traverseTree(ctx, nodeTarget, nodeLocation, *node.Subtree, visitor))
if err != nil {
return err
}
}
if selectedForRestore {
err = sanitizeError(visitor.leaveDir(node, nodeTarget, nodeLocation))
if err != nil {
return err
}
}
continue
}
if selectedForRestore {
err = sanitizeError(visitor.visitNode(node, nodeTarget, nodeLocation))
if err != nil {
return err
}
}
}
return nil
}
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)
}
// RestoreTo creates the directories and files in the snapshot below dst.
// Before an item is created, res.Filter is called.
func (res *Restorer) RestoreTo(ctx context.Context, dst string) error {
var err error
if !filepath.IsAbs(dst) {
dst, err = filepath.Abs(dst)
if err != nil {
return errors.Wrap(err, "Abs")
}
}
restoreNodeMetadata := func(node *restic.Node, target, location string) error {
return res.restoreNodeMetadataTo(node, target, location)
}
noop := func(node *restic.Node, target, location string) error { return nil }
idx := restic.NewHardlinkIndex()
filerestorer := newFileRestorer(dst, res.repo.Backend().Load, res.repo.Key(), res.repo.Index().Lookup)
// 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 {
// 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 {
// 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
},
leaveDir: noop,
})
if err != nil {
return err
}
err = filerestorer.restoreFiles(ctx)
if err != nil {
return err
}
// second tree pass: restore special files and filesystem metadata
return res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
enterDir: noop,
visitNode: func(node *restic.Node, target, location string) error {
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: restoreNodeMetadata,
})
}
// Snapshot returns the snapshot this restorer is configured to use.
func (res *Restorer) Snapshot() *restic.Snapshot {
return res.sn
}
// VerifyFiles reads all snapshot files and verifies their contents
func (res *Restorer) VerifyFiles(ctx context.Context, dst string) (int, error) {
// TODO multithreaded?
count := 0
err := res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
enterDir: func(node *restic.Node, target, location string) error { return nil },
visitNode: func(node *restic.Node, target, location string) error {
if node.Type != "file" {
return nil
}
count++
stat, err := os.Stat(target)
if err != nil {
return err
}
if int64(node.Size) != stat.Size() {
return errors.Errorf("Invalid file size: expected %d got %d", node.Size, stat.Size())
}
file, err := os.Open(target)
if err != nil {
return err
}
offset := int64(0)
for _, blobID := range node.Content {
length, _ := res.repo.LookupBlobSize(blobID, restic.DataBlob)
buf := make([]byte, length) // TODO do I want to reuse the buffer somehow?
_, err = file.ReadAt(buf, offset)
if err != nil {
_ = file.Close()
return err
}
if !blobID.Equal(restic.Hash(buf)) {
_ = file.Close()
return errors.Errorf("Unexpected contents starting at offset %d", offset)
}
offset += int64(length)
}
err = file.Close()
if err != nil {
return err
}
return nil
},
leaveDir: func(node *restic.Node, target, location string) error { return nil },
})
return count, err
}