sftp: Integrate command

src/restic/backend/sftp/config.go

@@ -11,6 +11,7 @@ import (
 // Config collects all information required to connect to an sftp server.
 type Config struct {
 	User, Host, Dir string
+	Command         string `option:"command"`
 }
 
 // ParseConfig parses the string s and extracts the sftp config. The

src/restic/backend/sftp/sftp.go

@@ -37,6 +37,7 @@ type SFTP struct {
 var _ restic.Backend = &SFTP{}
 
 func startClient(program string, args ...string) (*SFTP, error) {
+	debug.Log("start client %v %v", program, args)
 	// Connect to a remote host and request the sftp subsystem via the 'ssh'
 	// command.  This assumes that passwordless login is correctly configured.
 	cmd := exec.Command(program, args...)
@@ -114,11 +115,11 @@ func (r *SFTP) clientError() error {
 	return nil
 }
 
-// Open opens an sftp backend. When the command is started via
+// open opens an sftp backend. When the command is started via
 // exec.Command, it is expected to speak sftp on stdin/stdout. The backend
 // is expected at the given path. `dir` must be delimited by forward slashes
 // ("/"), which is required by sftp.
-func Open(dir string, program string, args ...string) (*SFTP, error) {
+func open(dir string, program string, args ...string) (*SFTP, error) {
 	debug.Log("open backend with program %v, %v at %v", program, args, dir)
 	sftp, err := startClient(program, args...)
 	if err != nil {
@@ -155,15 +156,25 @@ func buildSSHCommand(cfg Config) []string {
 // OpenWithConfig opens an sftp backend as described by the config by running
 // "ssh" with the appropriate arguments.
 func OpenWithConfig(cfg Config) (*SFTP, error) {
-	debug.Log("open with config %v", cfg)
-	return Open(cfg.Dir, "ssh", buildSSHCommand(cfg)...)
+	debug.Log("config %#v", cfg)
+
+	if cfg.Command == "" {
+		return open(cfg.Dir, "ssh", buildSSHCommand(cfg)...)
 	}
 
-// Create creates all the necessary files and directories for a new sftp
+	cmd, args, err := SplitShellArgs(cfg.Command)
+	if err != nil {
+		return nil, err
+	}
+
+	return open(cfg.Dir, cmd, args...)
+}
+
+// create creates all the necessary files and directories for a new sftp
 // backend at dir. Afterwards a new config blob should be created. `dir` must
 // be delimited by forward slashes ("/"), which is required by sftp.
-func Create(dir string, program string, args ...string) (*SFTP, error) {
-	debug.Log("%v %v", program, args)
+func create(dir string, program string, args ...string) (*SFTP, error) {
+	debug.Log("create() %v %v", program, args)
 	sftp, err := startClient(program, args...)
 	if err != nil {
 		return nil, err
@@ -178,6 +189,7 @@ func Create(dir string, program string, args ...string) (*SFTP, error) {
 	// create paths for data, refs and temp blobs
 	for _, d := range paths(dir) {
 		err = sftp.mkdirAll(d, backend.Modes.Dir)
+		debug.Log("mkdirAll %v -> %v", d, err)
 		if err != nil {
 			return nil, err
 		}
@@ -189,14 +201,23 @@ func Create(dir string, program string, args ...string) (*SFTP, error) {
 	}
 
 	// open backend
-	return Open(dir, program, args...)
+	return open(dir, program, args...)
 }
 
 // CreateWithConfig creates an sftp backend as described by the config by running
 // "ssh" with the appropriate arguments.
 func CreateWithConfig(cfg Config) (*SFTP, error) {
-	debug.Log("config %v", cfg)
-	return Create(cfg.Dir, "ssh", buildSSHCommand(cfg)...)
+	debug.Log("config %#v", cfg)
+	if cfg.Command == "" {
+		return create(cfg.Dir, "ssh", buildSSHCommand(cfg)...)
+	}
+
+	cmd, args, err := SplitShellArgs(cfg.Command)
+	if err != nil {
+		return nil, err
+	}
+
+	return create(cfg.Dir, cmd, args...)
 }
 
 // Location returns this backend's location (the directory name).

src/restic/backend/sftp/sftp_backend_test.go

@@ -1,6 +1,7 @@
 package sftp_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -50,7 +51,9 @@ func init() {
 		return
 	}
 
-	args := []string{"-e"}
+	cfg := sftp.Config{
+		Command: fmt.Sprintf("%q -e", sftpserver),
+	}
 
 	test.CreateFn = func() (restic.Backend, error) {
 		err := createTempdir()
@@ -58,7 +61,9 @@ func init() {
 			return nil, err
 		}
 
-		return sftp.Create(tempBackendDir, sftpserver, args...)
+		cfg.Dir = tempBackendDir
+
+		return sftp.CreateWithConfig(cfg)
 	}
 
 	test.OpenFn = func() (restic.Backend, error) {
@@ -66,7 +71,10 @@ func init() {
 		if err != nil {
 			return nil, err
 		}
-		return sftp.Open(tempBackendDir, sftpserver, args...)
+
+		cfg.Dir = tempBackendDir
+
+		return sftp.OpenWithConfig(cfg)
 	}
 
 	test.CleanupFn = func() error {

src/restic/backend/sftp/split.go

@@ -43,7 +43,7 @@ func (s *shellSplitter) isSplitChar(c rune) bool {
 }
 
 // SplitShellArgs returns the list of arguments from a shell command string.
-func SplitShellArgs(data string) (list []string, err error) {
+func SplitShellArgs(data string) (cmd string, args []string, err error) {
 	s := &shellSplitter{}
 
 	// derived from strings.SplitFunc
@@ -51,7 +51,7 @@ func SplitShellArgs(data string) (list []string, err error) {
 	for i, rune := range data {
 		if s.isSplitChar(rune) {
 			if fieldStart >= 0 {
-				list = append(list, data[fieldStart:i])
+				args = append(args, data[fieldStart:i])
 				fieldStart = -1
 			}
 		} else if fieldStart == -1 {
@@ -59,15 +59,21 @@ func SplitShellArgs(data string) (list []string, err error) {
 		}
 	}
 	if fieldStart >= 0 { // Last field might end at EOF.
-		list = append(list, data[fieldStart:])
+		args = append(args, data[fieldStart:])
 	}
 
 	switch s.quote {
 	case '\'':
-		return nil, errors.New("single-quoted string not terminated")
+		return "", nil, errors.New("single-quoted string not terminated")
 	case '"':
-		return nil, errors.New("double-quoted string not terminated")
+		return "", nil, errors.New("double-quoted string not terminated")
 	}
 
-	return list, nil
+	if len(args) == 0 {
+		return "", nil, errors.New("command string is empty")
+	}
+
+	cmd, args = args[0], args[1:]
+
+	return cmd, args, nil
 }

src/restic/backend/sftp/split_test.go

@@ -8,56 +8,62 @@ import (
 func TestShellSplitter(t *testing.T) {
 	var tests = []struct {
 		data string
-		want []string
+		cmd  string
+		args []string
 	}{
 		{
 			`foo`,
-			[]string{"foo"},
+			"foo", []string{},
 		},
 		{
 			`'foo'`,
-			[]string{"foo"},
+			"foo", []string{},
 		},
 		{
 			`foo bar baz`,
-			[]string{"foo", "bar", "baz"},
+			"foo", []string{"bar", "baz"},
 		},
 		{
 			`foo 'bar' baz`,
-			[]string{"foo", "bar", "baz"},
+			"foo", []string{"bar", "baz"},
 		},
 		{
-			`foo 'bar box' baz`,
-			[]string{"foo", "bar box", "baz"},
+			`'bar box' baz`,
+			"bar box", []string{"baz"},
 		},
 		{
 			`"bar 'box'" baz`,
-			[]string{"bar 'box'", "baz"},
+			"bar 'box'", []string{"baz"},
 		},
 		{
 			`'bar "box"' baz`,
-			[]string{`bar "box"`, "baz"},
+			`bar "box"`, []string{"baz"},
 		},
 		{
 			`\"bar box baz`,
-			[]string{`"bar`, "box", "baz"},
+			`"bar`, []string{"box", "baz"},
 		},
 		{
 			`"bar/foo/x" "box baz"`,
-			[]string{"bar/foo/x", "box baz"},
+			"bar/foo/x", []string{"box baz"},
 		},
 	}
 
 	for _, test := range tests {
 		t.Run("", func(t *testing.T) {
-			res, err := SplitShellArgs(test.data)
+			cmd, args, err := SplitShellArgs(test.data)
 			if err != nil {
 				t.Fatal(err)
 			}
 
-			if !reflect.DeepEqual(res, test.want) {
-				t.Fatalf("wrong data returned, want:\n  %#v\ngot:\n  %#v",
-					test.want, res)
+			if cmd != test.cmd {
+				t.Fatalf("wrong cmd returned, want:\n  %#v\ngot:\n  %#v",
+					test.cmd, cmd)
+			}
+
+			if !reflect.DeepEqual(args, test.args) {
+				t.Fatalf("wrong args returned, want:\n  %#v\ngot:\n  %#v",
+					test.args, args)
 			}
 		})
 	}
@@ -88,7 +94,7 @@ func TestShellSplitterInvalid(t *testing.T) {
 
 	for _, test := range tests {
 		t.Run("", func(t *testing.T) {
-			res, err := SplitShellArgs(test.data)
+			cmd, args, err := SplitShellArgs(test.data)
 			if err == nil {
 				t.Fatalf("expected error not found: %v", test.err)
 			}
@@ -97,8 +103,12 @@ func TestShellSplitterInvalid(t *testing.T) {
 				t.Fatalf("expected error not found, want:\n  %q\ngot:\n  %q", test.err, err.Error())
 			}
 
-			if len(res) > 0 {
-				t.Fatalf("splitter returned fields from invalid data: %v", res)
+			if cmd != "" {
+				t.Fatalf("splitter returned cmd from invalid data: %v", cmd)
+			}
+
+			if len(args) > 0 {
+				t.Fatalf("splitter returned fields from invalid data: %v", args)
 			}
 		})
 	}