mirror of
https://github.com/octoleo/restic.git
synced 2024-12-30 21:41:54 +00:00
417 lines
12 KiB
Go
417 lines
12 KiB
Go
package restorer
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import (
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"context"
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"os"
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"path/filepath"
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"sync/atomic"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/fs"
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"github.com/restic/restic/internal/restic"
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"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 {
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repo restic.Repository
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sn *restic.Snapshot
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Error func(location string, err error) error
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SelectFilter func(item string, dstpath string, node *restic.Node) (selectedForRestore bool, childMayBeSelected bool)
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}
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var restorerAbortOnAllErrors = func(location string, err error) error { return err }
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// NewRestorer creates a restorer preloaded with the content from the snapshot id.
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func NewRestorer(ctx context.Context, repo restic.Repository, id restic.ID) (*Restorer, error) {
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r := &Restorer{
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repo: repo,
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Error: restorerAbortOnAllErrors,
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SelectFilter: func(string, string, *restic.Node) (bool, bool) { return true, true },
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}
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var err error
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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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}
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return r, nil
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}
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type treeVisitor struct {
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enterDir func(node *restic.Node, target, location string) error
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visitNode func(node *restic.Node, target, location string) error
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leaveDir func(node *restic.Node, target, location string) error
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}
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// traverseTree traverses a tree from the repo and calls treeVisitor.
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// target is the path in the file system, location within the snapshot.
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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)
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return hasRestored, res.Error(location, err)
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}
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for _, node := range tree.Nodes {
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// ensure that the node name does not contain anything that refers to a
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// top-level directory.
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nodeName := filepath.Base(filepath.Join(string(filepath.Separator), node.Name))
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if nodeName != node.Name {
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debug.Log("node %q has invalid name %q", node.Name, nodeName)
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err := res.Error(location, errors.Errorf("invalid child node name %s", node.Name))
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if err != nil {
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return hasRestored, err
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}
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continue
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}
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nodeTarget := filepath.Join(target, nodeName)
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nodeLocation := filepath.Join(location, nodeName)
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if target == nodeTarget || !fs.HasPathPrefix(target, nodeTarget) {
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debug.Log("target: %v %v", target, nodeTarget)
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debug.Log("node %q has invalid target path %q", node.Name, nodeTarget)
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err := res.Error(nodeLocation, errors.New("node has invalid path"))
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if err != nil {
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return hasRestored, err
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}
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continue
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}
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// sockets cannot be restored
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if node.Type == "socket" {
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continue
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}
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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 {
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hasRestored = true
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}
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sanitizeError := func(err error) error {
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switch err {
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case nil, context.Canceled, context.DeadlineExceeded:
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// Context errors are permanent.
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return err
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default:
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return res.Error(nodeLocation, err)
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}
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}
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if node.Type == "dir" {
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if node.Subtree == nil {
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return hasRestored, errors.Errorf("Dir without subtree in tree %v", treeID.Str())
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}
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if selectedForRestore && visitor.enterDir != nil {
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err = sanitizeError(visitor.enterDir(node, nodeTarget, nodeLocation))
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if err != nil {
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return hasRestored, err
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}
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}
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// keep track of restored child status
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// so metadata of the current directory are restored on leaveDir
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childHasRestored := false
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if childMayBeSelected {
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childHasRestored, err = res.traverseTree(ctx, nodeTarget, nodeLocation, *node.Subtree, visitor)
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err = sanitizeError(err)
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if err != nil {
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return hasRestored, err
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}
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// inform the parent directory to restore parent metadata on leaveDir if needed
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if childHasRestored {
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hasRestored = true
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}
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}
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// metadata need to be restore when leaving the directory in both cases
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// selected for restore or any child of any subtree have been restored
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if (selectedForRestore || childHasRestored) && visitor.leaveDir != nil {
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err = sanitizeError(visitor.leaveDir(node, nodeTarget, nodeLocation))
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if err != nil {
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return hasRestored, err
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}
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}
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continue
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}
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if selectedForRestore {
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err = sanitizeError(visitor.visitNode(node, nodeTarget, nodeLocation))
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if err != nil {
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return hasRestored, err
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}
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}
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}
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return hasRestored, nil
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}
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func (res *Restorer) restoreNodeTo(ctx context.Context, node *restic.Node, target, location string) error {
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debug.Log("restoreNode %v %v %v", node.Name, target, location)
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err := node.CreateAt(ctx, target, res.repo)
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if err != nil {
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debug.Log("node.CreateAt(%s) error %v", target, err)
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}
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if err == nil {
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err = res.restoreNodeMetadataTo(node, target, location)
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}
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return err
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}
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func (res *Restorer) restoreNodeMetadataTo(node *restic.Node, target, location string) error {
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debug.Log("restoreNodeMetadata %v %v %v", node.Name, target, location)
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err := node.RestoreMetadata(target)
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if err != nil {
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debug.Log("node.RestoreMetadata(%s) error %v", target, err)
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}
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return err
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}
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func (res *Restorer) restoreHardlinkAt(node *restic.Node, target, path, location string) error {
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if err := fs.Remove(path); !os.IsNotExist(err) {
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return errors.Wrap(err, "RemoveCreateHardlink")
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}
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err := fs.Link(target, path)
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if err != nil {
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return errors.Wrap(err, "CreateHardlink")
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}
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// TODO investigate if hardlinks have separate metadata on any supported system
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return res.restoreNodeMetadataTo(node, path, location)
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}
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func (res *Restorer) restoreEmptyFileAt(node *restic.Node, target, location string) error {
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wr, err := os.OpenFile(target, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0600)
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if err != nil {
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return err
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}
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err = wr.Close()
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if err != nil {
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return err
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}
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return res.restoreNodeMetadataTo(node, target, location)
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}
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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.
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func (res *Restorer) RestoreTo(ctx context.Context, dst string) error {
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var err error
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if !filepath.IsAbs(dst) {
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dst, err = filepath.Abs(dst)
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if err != nil {
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return errors.Wrap(err, "Abs")
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}
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}
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idx := restic.NewHardlinkIndex()
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filerestorer := newFileRestorer(dst, res.repo.Backend().Load, res.repo.Key(), res.repo.Index().Lookup)
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filerestorer.Error = res.Error
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debug.Log("first pass for %q", dst)
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// first tree pass: create directories and collect all files to restore
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_, err = res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
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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)
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// create dir with default permissions
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// #leaveDir restores dir metadata after visiting all children
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return fs.MkdirAll(target, 0700)
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},
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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)
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// create parent dir with default permissions
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// second pass #leaveDir restores dir metadata after visiting/restoring all children
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err := fs.MkdirAll(filepath.Dir(target), 0700)
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if err != nil {
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return err
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}
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if node.Type != "file" {
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return nil
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}
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if node.Size == 0 {
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return nil // deal with empty files later
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}
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if node.Links > 1 {
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if idx.Has(node.Inode, node.DeviceID) {
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return nil
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}
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idx.Add(node.Inode, node.DeviceID, location)
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}
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filerestorer.addFile(location, node.Content, int64(node.Size))
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return nil
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},
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})
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if err != nil {
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return err
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}
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err = filerestorer.restoreFiles(ctx)
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if err != nil {
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return err
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}
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debug.Log("second pass for %q", dst)
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// second tree pass: restore special files and filesystem metadata
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_, err = res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
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visitNode: func(node *restic.Node, target, location string) error {
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debug.Log("second pass, visitNode: restore node %q", location)
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if node.Type != "file" {
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return res.restoreNodeTo(ctx, node, target, location)
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}
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// create empty files, but not hardlinks to empty files
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if node.Size == 0 && (node.Links < 2 || !idx.Has(node.Inode, node.DeviceID)) {
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if node.Links > 1 {
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idx.Add(node.Inode, node.DeviceID, location)
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}
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return res.restoreEmptyFileAt(node, target, location)
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}
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if idx.Has(node.Inode, node.DeviceID) && idx.GetFilename(node.Inode, node.DeviceID) != location {
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return res.restoreHardlinkAt(node, filerestorer.targetPath(idx.GetFilename(node.Inode, node.DeviceID)), target, location)
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}
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return res.restoreNodeMetadataTo(node, target, location)
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},
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leaveDir: res.restoreNodeMetadataTo,
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})
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return err
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}
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// Snapshot returns the snapshot this restorer is configured to use.
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func (res *Restorer) Snapshot() *restic.Snapshot {
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return res.sn
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}
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// Number of workers in VerifyFiles.
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const nVerifyWorkers = 8
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// VerifyFiles checks whether all regular files in the snapshot res.sn
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// have been successfully written to dst. It stops when it encounters an
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// error. It returns that error and the number of files it has successfully
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// verified.
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func (res *Restorer) VerifyFiles(ctx context.Context, dst string) (int, error) {
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type mustCheck struct {
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node *restic.Node
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path string
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}
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var (
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nchecked uint64
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work = make(chan mustCheck, 2*nVerifyWorkers)
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)
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g, ctx := errgroup.WithContext(ctx)
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// Traverse tree and send jobs to work.
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g.Go(func() error {
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defer close(work)
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_, err := res.traverseTree(ctx, dst, string(filepath.Separator), *res.sn.Tree, treeVisitor{
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visitNode: func(node *restic.Node, target, location string) error {
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if node.Type != "file" {
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return nil
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}
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select {
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case <-ctx.Done():
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return ctx.Err()
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case work <- mustCheck{node, target}:
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return nil
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}
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},
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})
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return err
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})
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for i := 0; i < nVerifyWorkers; i++ {
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g.Go(func() (err error) {
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var buf []byte
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for job := range work {
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buf, err = res.verifyFile(job.path, job.node, buf)
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if err != nil {
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err = res.Error(job.path, err)
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}
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if err != nil || ctx.Err() != nil {
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break
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}
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atomic.AddUint64(&nchecked, 1)
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}
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return err
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})
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}
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return int(nchecked), g.Wait()
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}
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// Verify that the file target has the contents of node.
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//
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// buf and the first return value are scratch space, passed around for reuse.
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// Reusing buffers prevents the verifier goroutines allocating all of RAM and
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// flushing the filesystem cache (at least on Linux).
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func (res *Restorer) verifyFile(target string, node *restic.Node, buf []byte) ([]byte, error) {
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f, err := os.Open(target)
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if err != nil {
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return buf, err
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}
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defer func() {
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_ = f.Close()
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}()
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fi, err := f.Stat()
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switch {
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case err != nil:
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return buf, err
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case int64(node.Size) != fi.Size():
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return buf, errors.Errorf("Invalid file size for %s: expected %d, got %d",
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target, node.Size, fi.Size())
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}
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var offset int64
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for _, blobID := range node.Content {
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length, found := res.repo.LookupBlobSize(blobID, restic.DataBlob)
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if !found {
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return buf, errors.Errorf("Unable to fetch blob %s", blobID)
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}
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if length > uint(cap(buf)) {
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buf = make([]byte, 2*length)
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}
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buf = buf[:length]
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_, err = f.ReadAt(buf, offset)
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if err != nil {
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return buf, err
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}
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if !blobID.Equal(restic.Hash(buf)) {
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return buf, errors.Errorf(
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"Unexpected content in %s, starting at offset %d",
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target, offset)
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}
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offset += int64(length)
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}
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return buf, nil
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}
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