Merge pull request #1346 from fawick/cmdCatFile

Add dump sub-command for dumping files to stdout

cmd/restic/cmd_debug.go

@@ -24,7 +24,7 @@ var cmdDebug = &cobra.Command{
 	Short: "Debug commands",
 }
 
-var cmdDump = &cobra.Command{
+var cmdDebugDump = &cobra.Command{
 	Use:   "dump [indexes|snapshots|all|packs]",
 	Short: "Dump data structures",
 	Long: `
@@ -32,13 +32,13 @@ The "dump" command dumps data structures from the repository as JSON objects. It
 is used for debugging purposes only.`,
 	DisableAutoGenTag: true,
 	RunE: func(cmd *cobra.Command, args []string) error {
-		return runDump(globalOptions, args)
+		return runDebugDump(globalOptions, args)
 	},
 }
 
 func init() {
 	cmdRoot.AddCommand(cmdDebug)
-	cmdDebug.AddCommand(cmdDump)
+	cmdDebug.AddCommand(cmdDebugDump)
 }
 
 func prettyPrintJSON(wr io.Writer, item interface{}) error {
@@ -165,7 +165,7 @@ func dumpIndexes(repo restic.Repository) error {
 	return nil
 }
 
-func runDump(gopts GlobalOptions, args []string) error {
+func runDebugDump(gopts GlobalOptions, args []string) error {
 	if len(args) != 1 {
 		return errors.Fatal("type not specified")
 	}

cmd/restic/cmd_dump.go

@@ -0,0 +1,181 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/restic/restic/internal/debug"
+	"github.com/restic/restic/internal/errors"
+	"github.com/restic/restic/internal/restic"
+
+	"github.com/spf13/cobra"
+)
+
+var cmdDump = &cobra.Command{
+	Use:   "dump [flags] snapshotID file",
+	Short: "Print a backed-up file to stdout",
+	Long: `
+The "dump" command extracts a single file from a snapshot from the repository and
+prints its contents to stdout.
+
+The special snapshot "latest" can be used to use the latest snapshot in the
+repository.
+`,
+	DisableAutoGenTag: true,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		return runDump(dumpOptions, globalOptions, args)
+	},
+}
+
+// DumpOptions collects all options for the dump command.
+type DumpOptions struct {
+	Host  string
+	Paths []string
+	Tags  restic.TagLists
+}
+
+var dumpOptions DumpOptions
+
+func init() {
+	cmdRoot.AddCommand(cmdDump)
+
+	flags := cmdDump.Flags()
+	flags.StringVarP(&dumpOptions.Host, "host", "H", "", `only consider snapshots for this host when the snapshot ID is "latest"`)
+	flags.Var(&dumpOptions.Tags, "tag", "only consider snapshots which include this `taglist` for snapshot ID \"latest\"")
+	flags.StringArrayVar(&dumpOptions.Paths, "path", nil, "only consider snapshots which include this (absolute) `path` for snapshot ID \"latest\"")
+}
+
+func splitPath(path string) []string {
+	d, f := filepath.Split(path)
+	if d == "" {
+		return []string{f}
+	}
+	s := splitPath(filepath.Clean(d))
+	return append(s, f)
+}
+
+func dumpNode(ctx context.Context, repo restic.Repository, node *restic.Node) error {
+	var buf []byte
+	for _, id := range node.Content {
+		size, err := repo.LookupBlobSize(id, restic.DataBlob)
+		if err != nil {
+			return err
+		}
+
+		buf = buf[:cap(buf)]
+		if len(buf) < restic.CiphertextLength(int(size)) {
+			buf = restic.NewBlobBuffer(int(size))
+		}
+
+		n, err := repo.LoadBlob(ctx, restic.DataBlob, id, buf)
+		if err != nil {
+			return err
+		}
+		buf = buf[:n]
+
+		_, err = os.Stdout.Write(buf)
+		if err != nil {
+			return errors.Wrap(err, "Write")
+		}
+	}
+	return nil
+}
+
+func printFromTree(ctx context.Context, tree *restic.Tree, repo restic.Repository, prefix string, pathComponents []string) error {
+	if tree == nil {
+		return fmt.Errorf("called with a nil tree")
+	}
+	if repo == nil {
+		return fmt.Errorf("called with a nil repository")
+	}
+	l := len(pathComponents)
+	if l == 0 {
+		return fmt.Errorf("empty path components")
+	}
+	item := filepath.Join(prefix, pathComponents[0])
+	for _, node := range tree.Nodes {
+		if node.Name == pathComponents[0] {
+			switch {
+			case l == 1 && node.Type == "file":
+				return dumpNode(ctx, repo, node)
+			case l > 1 && node.Type == "dir":
+				subtree, err := repo.LoadTree(ctx, *node.Subtree)
+				if err != nil {
+					return errors.Wrapf(err, "cannot load subtree for %q", item)
+				}
+				return printFromTree(ctx, subtree, repo, item, pathComponents[1:])
+			case l > 1:
+				return fmt.Errorf("%q should be a dir, but s a %q", item, node.Type)
+			case node.Type != "file":
+				return fmt.Errorf("%q should be a file, but is a %q", item, node.Type)
+			}
+		}
+	}
+	return fmt.Errorf("path %q not found in snapshot", item)
+}
+
+func runDump(opts DumpOptions, gopts GlobalOptions, args []string) error {
+	ctx := gopts.ctx
+
+	if len(args) != 2 {
+		return errors.Fatal("no file and no snapshot ID specified")
+	}
+
+	snapshotIDString := args[0]
+	pathToPrint := args[1]
+
+	debug.Log("dump file %q from %q", pathToPrint, snapshotIDString)
+
+	splittedPath := splitPath(pathToPrint)
+
+	repo, err := OpenRepository(gopts)
+	if err != nil {
+		return err
+	}
+
+	if !gopts.NoLock {
+		lock, err := lockRepo(repo)
+		defer unlockRepo(lock)
+		if err != nil {
+			return err
+		}
+	}
+
+	err = repo.LoadIndex(ctx)
+	if err != nil {
+		return err
+	}
+
+	var id restic.ID
+
+	if snapshotIDString == "latest" {
+		id, err = restic.FindLatestSnapshot(ctx, repo, opts.Paths, opts.Tags, opts.Host)
+		if err != nil {
+			Exitf(1, "latest snapshot for criteria not found: %v Paths:%v Host:%v", err, opts.Paths, opts.Host)
+		}
+	} else {
+		id, err = restic.FindSnapshot(repo, snapshotIDString)
+		if err != nil {
+			Exitf(1, "invalid id %q: %v", snapshotIDString, err)
+		}
+	}
+
+	sn, err := restic.LoadSnapshot(context.TODO(), repo, id)
+	if err != nil {
+		Exitf(2, "loading snapshot %q failed: %v", snapshotIDString, err)
+	}
+
+	tree, err := repo.LoadTree(ctx, *sn.Tree)
+	if err != nil {
+		Exitf(2, "loading tree for snapshot %q failed: %v", snapshotIDString, err)
+	}
+
+	err = printFromTree(ctx, tree, repo, "", splittedPath)
+	if err != nil {
+		Exitf(2, "cannot dump file: %v", err)
+	}
+
+	return nil
+}