hashsum: make generic tool for any hash to produce md5sum like output

cmd/all/all.go

@@ -21,6 +21,7 @@ import (
 	_ "github.com/ncw/rclone/cmd/delete"
 	_ "github.com/ncw/rclone/cmd/genautocomplete"
 	_ "github.com/ncw/rclone/cmd/gendocs"
+	_ "github.com/ncw/rclone/cmd/hashsum"
 	_ "github.com/ncw/rclone/cmd/info"
 	_ "github.com/ncw/rclone/cmd/link"
 	_ "github.com/ncw/rclone/cmd/listremotes"

cmd/hashsum/hashsum.go

@@ -0,0 +1,61 @@
+package hashsum
+
+import (
+	"errors"
+	"fmt"
+	"os"
+
+	"github.com/ncw/rclone/cmd"
+	"github.com/ncw/rclone/fs/hash"
+	"github.com/ncw/rclone/fs/operations"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	cmd.Root.AddCommand(commandDefinition)
+}
+
+var commandDefinition = &cobra.Command{
+	Use:   "hashsum <hash> remote:path",
+	Short: `Produces an hashsum file for all the objects in the path.`,
+	Long: `
+Produces a hash file for all the objects in the path using the hash
+named.  The output is in the same format as the standard
+md5sum/sha1sum tool.
+
+Run without a hash to see the list of supported hashes, eg
+
+    $ rclone hashsum
+    Supported hashes are:
+      * MD5
+      * SHA-1
+      * DropboxHash
+      * QuickXorHash
+
+Then
+
+    $ rclone hashsum MD5 remote:path
+`,
+	RunE: func(command *cobra.Command, args []string) error {
+		cmd.CheckArgs(0, 2, command, args)
+		if len(args) == 0 {
+			fmt.Printf("Supported hashes are:\n")
+			for _, ht := range hash.Supported.Array() {
+				fmt.Printf("  * %v\n", ht)
+			}
+			return nil
+		} else if len(args) == 1 {
+			return errors.New("need hash type and remote")
+		}
+		var ht hash.Type
+		err := ht.Set(args[0])
+		if err != nil {
+			return err
+		}
+		fsrc := cmd.NewFsSrc(args[1:])
+		cmd.Run(false, false, command, func() error {
+			return operations.HashLister(ht, fsrc, os.Stdout)
+		})
+		return nil
+	},
+}

fs/operations/operations.go

@@ -840,7 +840,7 @@ func ListLong(f fs.Fs, w io.Writer) error {
 //
 // Lists in parallel which may get them out of order
 func Md5sum(f fs.Fs, w io.Writer) error {
-	return hashLister(hash.MD5, f, w)
+	return HashLister(hash.MD5, f, w)
 }
 
 // Sha1sum list the Fs to the supplied writer
@@ -849,7 +849,7 @@ func Md5sum(f fs.Fs, w io.Writer) error {
 //
 // Lists in parallel which may get them out of order
 func Sha1sum(f fs.Fs, w io.Writer) error {
-	return hashLister(hash.SHA1, f, w)
+	return HashLister(hash.SHA1, f, w)
 }
 
 // DropboxHashSum list the Fs to the supplied writer
@@ -858,7 +858,7 @@ func Sha1sum(f fs.Fs, w io.Writer) error {
 //
 // Lists in parallel which may get them out of order
 func DropboxHashSum(f fs.Fs, w io.Writer) error {
-	return hashLister(hash.Dropbox, f, w)
+	return HashLister(hash.Dropbox, f, w)
 }
 
 // hashSum returns the human readable hash for ht passed in.  This may
@@ -876,7 +876,8 @@ func hashSum(ht hash.Type, o fs.Object) string {
 	return sum
 }
 
-func hashLister(ht hash.Type, f fs.Fs, w io.Writer) error {
+// HashLister does a md5sum equivalent for the hash type passed in
+func HashLister(ht hash.Type, f fs.Fs, w io.Writer) error {
 	return ListFn(f, func(o fs.Object) {
 		sum := hashSum(ht, o)
 		syncFprintf(w, "%*s  %s\n", hash.Width[ht], sum, o.Remote())