Working on SFTP

9 files changed, 928 insertions, 0 deletions

diff --git a/internal/encoding/ssh/filexfer/openssh/fsync.go b/internal/encoding/ssh/filexfer/openssh/fsync.go
new file mode 100644
index 0000000..7ecfb0c
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/fsync.go
@@ -0,0 +1,73 @@
+package openssh
+
+import (
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+const extensionFSync = "fsync@openssh.com"
+
+// RegisterExtensionFSync registers the "fsync@openssh.com" extended packet with the encoding/ssh/filexfer package.
+func RegisterExtensionFSync() {
+	sshfx.RegisterExtendedPacketType(extensionFSync, func() sshfx.ExtendedData {
+		return new(FSyncExtendedPacket)
+	})
+}
+
+// ExtensionFSync returns an ExtensionPair suitable to append into an sshfx.InitPacket or sshfx.VersionPacket.
+func ExtensionFSync() *sshfx.ExtensionPair {
+	return &sshfx.ExtensionPair{
+		Name: extensionFSync,
+		Data: "1",
+	}
+}
+
+// FSyncExtendedPacket defines the fsync@openssh.com extend packet.
+type FSyncExtendedPacket struct {
+	Handle string
+}
+
+// Type returns the SSH_FXP_EXTENDED packet type.
+func (ep *FSyncExtendedPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtended
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended packet.
+func (ep *FSyncExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedPacket{
+		ExtendedRequest: extensionFSync,
+
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// MarshalInto encodes ep into the binary encoding of the fsync@openssh.com extended packet-specific data.
+func (ep *FSyncExtendedPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendString(ep.Handle)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the fsync@openssh.com extended packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended packet.
+func (ep *FSyncExtendedPacket) MarshalBinary() ([]byte, error) {
+	// string(handle)
+	size := 4 + len(ep.Handle)
+
+	buf := sshfx.NewBuffer(make([]byte, 0, size))
+	ep.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the fsync@openssh.com extended packet-specific data from buf.
+func (ep *FSyncExtendedPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.Handle, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the fsync@openssh.com extended packet-specific data into ep.
+func (ep *FSyncExtendedPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/fsync_test.go b/internal/encoding/ssh/filexfer/openssh/fsync_test.go
new file mode 100644
index 0000000..f9e878f
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/fsync_test.go
@@ -0,0 +1,62 @@
+package openssh
+
+import (
+	"bytes"
+	"testing"
+
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+var _ sshfx.PacketMarshaller = &FSyncExtendedPacket{}
+
+func init() {
+	RegisterExtensionFSync()
+}
+
+func TestFSyncExtendedPacket(t *testing.T) {
+	const (
+		id     = 42
+		handle = "somehandle"
+	)
+
+	ep := &FSyncExtendedPacket{
+		Handle: handle,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 40,
+		200,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 17, 'f', 's', 'y', 'n', 'c', '@', 'o', 'p', 'e', 'n', 's', 's', 'h', '.', 'c', 'o', 'm',
+		0x00, 0x00, 0x00, 10, 's', 'o', 'm', 'e', 'h', 'a', 'n', 'd', 'l', 'e',
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	var p sshfx.ExtendedPacket
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	if p.ExtendedRequest != extensionFSync {
+		t.Errorf("UnmarshalPacketBody(): ExtendedRequest was %q, but expected %q", p.ExtendedRequest, extensionFSync)
+	}
+
+	ep, ok := p.Data.(*FSyncExtendedPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *FSyncExtendedPacket", p.Data)
+	}
+
+	if ep.Handle != handle {
+		t.Errorf("UnmarshalPacketBody(): Handle was %q, but expected %q", ep.Handle, handle)
+	}
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/hardlink.go b/internal/encoding/ssh/filexfer/openssh/hardlink.go
new file mode 100644
index 0000000..17c3499
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/hardlink.go
@@ -0,0 +1,79 @@
+package openssh
+
+import (
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+const extensionHardlink = "hardlink@openssh.com"
+
+// RegisterExtensionHardlink registers the "hardlink@openssh.com" extended packet with the encoding/ssh/filexfer package.
+func RegisterExtensionHardlink() {
+	sshfx.RegisterExtendedPacketType(extensionHardlink, func() sshfx.ExtendedData {
+		return new(HardlinkExtendedPacket)
+	})
+}
+
+// ExtensionHardlink returns an ExtensionPair suitable to append into an sshfx.InitPacket or sshfx.VersionPacket.
+func ExtensionHardlink() *sshfx.ExtensionPair {
+	return &sshfx.ExtensionPair{
+		Name: extensionHardlink,
+		Data: "1",
+	}
+}
+
+// HardlinkExtendedPacket defines the hardlink@openssh.com extend packet.
+type HardlinkExtendedPacket struct {
+	OldPath string
+	NewPath string
+}
+
+// Type returns the SSH_FXP_EXTENDED packet type.
+func (ep *HardlinkExtendedPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtended
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended packet.
+func (ep *HardlinkExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedPacket{
+		ExtendedRequest: extensionHardlink,
+
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// MarshalInto encodes ep into the binary encoding of the hardlink@openssh.com extended packet-specific data.
+func (ep *HardlinkExtendedPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendString(ep.OldPath)
+	buf.AppendString(ep.NewPath)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the hardlink@openssh.com extended packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended packet.
+func (ep *HardlinkExtendedPacket) MarshalBinary() ([]byte, error) {
+	// string(oldpath) + string(newpath)
+	size := 4 + len(ep.OldPath) + 4 + len(ep.NewPath)
+
+	buf := sshfx.NewBuffer(make([]byte, 0, size))
+	ep.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the hardlink@openssh.com extended packet-specific data from buf.
+func (ep *HardlinkExtendedPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.OldPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if ep.NewPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the hardlink@openssh.com extended packet-specific data into ep.
+func (ep *HardlinkExtendedPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/hardlink_test.go b/internal/encoding/ssh/filexfer/openssh/hardlink_test.go
new file mode 100644
index 0000000..5d3be06
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/hardlink_test.go
@@ -0,0 +1,69 @@
+package openssh
+
+import (
+	"bytes"
+	"testing"
+
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+var _ sshfx.PacketMarshaller = &HardlinkExtendedPacket{}
+
+func init() {
+	RegisterExtensionHardlink()
+}
+
+func TestHardlinkExtendedPacket(t *testing.T) {
+	const (
+		id      = 42
+		oldpath = "/foo"
+		newpath = "/bar"
+	)
+
+	ep := &HardlinkExtendedPacket{
+		OldPath: oldpath,
+		NewPath: newpath,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 45,
+		200,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 20, 'h', 'a', 'r', 'd', 'l', 'i', 'n', 'k', '@', 'o', 'p', 'e', 'n', 's', 's', 'h', '.', 'c', 'o', 'm',
+		0x00, 0x00, 0x00, 4, '/', 'f', 'o', 'o',
+		0x00, 0x00, 0x00, 4, '/', 'b', 'a', 'r',
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	var p sshfx.ExtendedPacket
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	if p.ExtendedRequest != extensionHardlink {
+		t.Errorf("UnmarshalPacketBody(): ExtendedRequest was %q, but expected %q", p.ExtendedRequest, extensionHardlink)
+	}
+
+	ep, ok := p.Data.(*HardlinkExtendedPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *HardlinkExtendedPacket", p.Data)
+	}
+
+	if ep.OldPath != oldpath {
+		t.Errorf("UnmarshalPacketBody(): OldPath was %q, but expected %q", ep.OldPath, oldpath)
+	}
+
+	if ep.NewPath != newpath {
+		t.Errorf("UnmarshalPacketBody(): NewPath was %q, but expected %q", ep.NewPath, newpath)
+	}
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/openssh.go b/internal/encoding/ssh/filexfer/openssh/openssh.go
new file mode 100644
index 0000000..f93ff17
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/openssh.go
@@ -0,0 +1,2 @@
+// Package openssh implements the openssh secsh-filexfer extensions as described in https://github.com/openssh/openssh-portable/blob/master/PROTOCOL
+package openssh
diff --git a/internal/encoding/ssh/filexfer/openssh/posix-rename.go b/internal/encoding/ssh/filexfer/openssh/posix-rename.go
new file mode 100644
index 0000000..a3d3de5
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/posix-rename.go
@@ -0,0 +1,79 @@
+package openssh
+
+import (
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+const extensionPosixRename = "posix-rename@openssh.com"
+
+// RegisterExtensionPosixRename registers the "posix-rename@openssh.com" extended packet with the encoding/ssh/filexfer package.
+func RegisterExtensionPosixRename() {
+	sshfx.RegisterExtendedPacketType(extensionPosixRename, func() sshfx.ExtendedData {
+		return new(PosixRenameExtendedPacket)
+	})
+}
+
+// ExtensionPosixRename returns an ExtensionPair suitable to append into an sshfx.InitPacket or sshfx.VersionPacket.
+func ExtensionPosixRename() *sshfx.ExtensionPair {
+	return &sshfx.ExtensionPair{
+		Name: extensionPosixRename,
+		Data: "1",
+	}
+}
+
+// PosixRenameExtendedPacket defines the posix-rename@openssh.com extend packet.
+type PosixRenameExtendedPacket struct {
+	OldPath string
+	NewPath string
+}
+
+// Type returns the SSH_FXP_EXTENDED packet type.
+func (ep *PosixRenameExtendedPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtended
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended packet.
+func (ep *PosixRenameExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedPacket{
+		ExtendedRequest: extensionPosixRename,
+
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// MarshalInto encodes ep into the binary encoding of the hardlink@openssh.com extended packet-specific data.
+func (ep *PosixRenameExtendedPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendString(ep.OldPath)
+	buf.AppendString(ep.NewPath)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the hardlink@openssh.com extended packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended packet.
+func (ep *PosixRenameExtendedPacket) MarshalBinary() ([]byte, error) {
+	// string(oldpath) + string(newpath)
+	size := 4 + len(ep.OldPath) + 4 + len(ep.NewPath)
+
+	buf := sshfx.NewBuffer(make([]byte, 0, size))
+	ep.MarshalInto(buf)
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the hardlink@openssh.com extended packet-specific data from buf.
+func (ep *PosixRenameExtendedPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.OldPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	if ep.NewPath, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the hardlink@openssh.com extended packet-specific data into ep.
+func (ep *PosixRenameExtendedPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/posix-rename_test.go b/internal/encoding/ssh/filexfer/openssh/posix-rename_test.go
new file mode 100644
index 0000000..6bdb10d
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/posix-rename_test.go
@@ -0,0 +1,69 @@
+package openssh
+
+import (
+	"bytes"
+	"testing"
+
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+var _ sshfx.PacketMarshaller = &PosixRenameExtendedPacket{}
+
+func init() {
+	RegisterExtensionPosixRename()
+}
+
+func TestPosixRenameExtendedPacket(t *testing.T) {
+	const (
+		id      = 42
+		oldpath = "/foo"
+		newpath = "/bar"
+	)
+
+	ep := &PosixRenameExtendedPacket{
+		OldPath: oldpath,
+		NewPath: newpath,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 49,
+		200,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 24, 'p', 'o', 's', 'i', 'x', '-', 'r', 'e', 'n', 'a', 'm', 'e', '@', 'o', 'p', 'e', 'n', 's', 's', 'h', '.', 'c', 'o', 'm',
+		0x00, 0x00, 0x00, 4, '/', 'f', 'o', 'o',
+		0x00, 0x00, 0x00, 4, '/', 'b', 'a', 'r',
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	var p sshfx.ExtendedPacket
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	if p.ExtendedRequest != extensionPosixRename {
+		t.Errorf("UnmarshalPacketBody(): ExtendedRequest was %q, but expected %q", p.ExtendedRequest, extensionPosixRename)
+	}
+
+	ep, ok := p.Data.(*PosixRenameExtendedPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *PosixRenameExtendedPacket", p.Data)
+	}
+
+	if ep.OldPath != oldpath {
+		t.Errorf("UnmarshalPacketBody(): OldPath was %q, but expected %q", ep.OldPath, oldpath)
+	}
+
+	if ep.NewPath != newpath {
+		t.Errorf("UnmarshalPacketBody(): NewPath was %q, but expected %q", ep.NewPath, newpath)
+	}
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/statvfs.go b/internal/encoding/ssh/filexfer/openssh/statvfs.go
new file mode 100644
index 0000000..3e9015f
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/statvfs.go
@@ -0,0 +1,256 @@
+package openssh
+
+import (
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+const extensionStatVFS = "statvfs@openssh.com"
+
+// RegisterExtensionStatVFS registers the "statvfs@openssh.com" extended packet with the encoding/ssh/filexfer package.
+func RegisterExtensionStatVFS() {
+	sshfx.RegisterExtendedPacketType(extensionStatVFS, func() sshfx.ExtendedData {
+		return new(StatVFSExtendedPacket)
+	})
+}
+
+// ExtensionStatVFS returns an ExtensionPair suitable to append into an sshfx.InitPacket or sshfx.VersionPacket.
+func ExtensionStatVFS() *sshfx.ExtensionPair {
+	return &sshfx.ExtensionPair{
+		Name: extensionStatVFS,
+		Data: "2",
+	}
+}
+
+// StatVFSExtendedPacket defines the statvfs@openssh.com extend packet.
+type StatVFSExtendedPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_EXTENDED packet type.
+func (ep *StatVFSExtendedPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtended
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended packet.
+func (ep *StatVFSExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedPacket{
+		ExtendedRequest: extensionStatVFS,
+
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// MarshalInto encodes ep into the binary encoding of the statvfs@openssh.com extended packet-specific data.
+func (ep *StatVFSExtendedPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendString(ep.Path)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the statvfs@openssh.com extended packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended packet.
+func (ep *StatVFSExtendedPacket) MarshalBinary() ([]byte, error) {
+	size := 4 + len(ep.Path) // string(path)
+
+	buf := sshfx.NewBuffer(make([]byte, 0, size))
+
+	ep.MarshalInto(buf)
+
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the statvfs@openssh.com extended packet-specific data into ep.
+func (ep *StatVFSExtendedPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the statvfs@openssh.com extended packet-specific data into ep.
+func (ep *StatVFSExtendedPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
+
+const extensionFStatVFS = "fstatvfs@openssh.com"
+
+// RegisterExtensionFStatVFS registers the "fstatvfs@openssh.com" extended packet with the encoding/ssh/filexfer package.
+func RegisterExtensionFStatVFS() {
+	sshfx.RegisterExtendedPacketType(extensionFStatVFS, func() sshfx.ExtendedData {
+		return new(FStatVFSExtendedPacket)
+	})
+}
+
+// ExtensionFStatVFS returns an ExtensionPair suitable to append into an sshfx.InitPacket or sshfx.VersionPacket.
+func ExtensionFStatVFS() *sshfx.ExtensionPair {
+	return &sshfx.ExtensionPair{
+		Name: extensionFStatVFS,
+		Data: "2",
+	}
+}
+
+// FStatVFSExtendedPacket defines the fstatvfs@openssh.com extend packet.
+type FStatVFSExtendedPacket struct {
+	Path string
+}
+
+// Type returns the SSH_FXP_EXTENDED packet type.
+func (ep *FStatVFSExtendedPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtended
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended packet.
+func (ep *FStatVFSExtendedPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedPacket{
+		ExtendedRequest: extensionFStatVFS,
+
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// MarshalInto encodes ep into the binary encoding of the statvfs@openssh.com extended packet-specific data.
+func (ep *FStatVFSExtendedPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendString(ep.Path)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the statvfs@openssh.com extended packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended packet.
+func (ep *FStatVFSExtendedPacket) MarshalBinary() ([]byte, error) {
+	size := 4 + len(ep.Path) // string(path)
+
+	buf := sshfx.NewBuffer(make([]byte, 0, size))
+
+	ep.MarshalInto(buf)
+
+	return buf.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the statvfs@openssh.com extended packet-specific data into ep.
+func (ep *FStatVFSExtendedPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.Path, err = buf.ConsumeString(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the statvfs@openssh.com extended packet-specific data into ep.
+func (ep *FStatVFSExtendedPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
+
+// The values for the MountFlags field.
+// https://github.com/openssh/openssh-portable/blob/master/PROTOCOL
+const (
+	MountFlagsReadOnly = 0x1 // SSH_FXE_STATVFS_ST_RDONLY
+	MountFlagsNoSUID   = 0x2 // SSH_FXE_STATVFS_ST_NOSUID
+)
+
+// StatVFSExtendedReplyPacket defines the extended reply packet for statvfs@openssh.com and fstatvfs@openssh.com requests.
+type StatVFSExtendedReplyPacket struct {
+	BlockSize     uint64 /* f_bsize:   file system block size */
+	FragmentSize  uint64 /* f_frsize:  fundamental fs block size / fagment size */
+	Blocks        uint64 /* f_blocks:  number of blocks (unit f_frsize) */
+	BlocksFree    uint64 /* f_bfree:   free blocks in filesystem */
+	BlocksAvail   uint64 /* f_bavail:  free blocks for non-root */
+	Files         uint64 /* f_files:   total file inodes */
+	FilesFree     uint64 /* f_ffree:   free file inodes */
+	FilesAvail    uint64 /* f_favail:  free file inodes for to non-root */
+	FilesystemID  uint64 /* f_fsid:    file system id */
+	MountFlags    uint64 /* f_flag:    bit mask of mount flag values */
+	MaxNameLength uint64 /* f_namemax: maximum filename length */
+}
+
+// Type returns the SSH_FXP_EXTENDED_REPLY packet type.
+func (ep *StatVFSExtendedReplyPacket) Type() sshfx.PacketType {
+	return sshfx.PacketTypeExtendedReply
+}
+
+// MarshalPacket returns ep as a two-part binary encoding of the full extended reply packet.
+func (ep *StatVFSExtendedReplyPacket) MarshalPacket(reqid uint32, b []byte) (header, payload []byte, err error) {
+	p := &sshfx.ExtendedReplyPacket{
+		Data: ep,
+	}
+	return p.MarshalPacket(reqid, b)
+}
+
+// UnmarshalPacketBody returns ep as a two-part binary encoding of the full extended reply packet.
+func (ep *StatVFSExtendedReplyPacket) UnmarshalPacketBody(buf *sshfx.Buffer) (err error) {
+	p := &sshfx.ExtendedReplyPacket{
+		Data: ep,
+	}
+	return p.UnmarshalPacketBody(buf)
+}
+
+// MarshalInto encodes ep into the binary encoding of the (f)statvfs@openssh.com extended reply packet-specific data.
+func (ep *StatVFSExtendedReplyPacket) MarshalInto(buf *sshfx.Buffer) {
+	buf.AppendUint64(ep.BlockSize)
+	buf.AppendUint64(ep.FragmentSize)
+	buf.AppendUint64(ep.Blocks)
+	buf.AppendUint64(ep.BlocksFree)
+	buf.AppendUint64(ep.BlocksAvail)
+	buf.AppendUint64(ep.Files)
+	buf.AppendUint64(ep.FilesFree)
+	buf.AppendUint64(ep.FilesAvail)
+	buf.AppendUint64(ep.FilesystemID)
+	buf.AppendUint64(ep.MountFlags)
+	buf.AppendUint64(ep.MaxNameLength)
+}
+
+// MarshalBinary encodes ep into the binary encoding of the (f)statvfs@openssh.com extended reply packet-specific data.
+//
+// NOTE: This _only_ encodes the packet-specific data, it does not encode the full extended reply packet.
+func (ep *StatVFSExtendedReplyPacket) MarshalBinary() ([]byte, error) {
+	size := 11 * 8 // 11 × uint64(various)
+
+	b := sshfx.NewBuffer(make([]byte, 0, size))
+	ep.MarshalInto(b)
+	return b.Bytes(), nil
+}
+
+// UnmarshalFrom decodes the fstatvfs@openssh.com extended reply packet-specific data into ep.
+func (ep *StatVFSExtendedReplyPacket) UnmarshalFrom(buf *sshfx.Buffer) (err error) {
+	if ep.BlockSize, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.FragmentSize, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.Blocks, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.BlocksFree, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.BlocksAvail, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.Files, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.FilesFree, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.FilesAvail, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.FilesystemID, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.MountFlags, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+	if ep.MaxNameLength, err = buf.ConsumeUint64(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// UnmarshalBinary decodes the fstatvfs@openssh.com extended reply packet-specific data into ep.
+func (ep *StatVFSExtendedReplyPacket) UnmarshalBinary(data []byte) (err error) {
+	return ep.UnmarshalFrom(sshfx.NewBuffer(data))
+}
diff --git a/internal/encoding/ssh/filexfer/openssh/statvfs_test.go b/internal/encoding/ssh/filexfer/openssh/statvfs_test.go
new file mode 100644
index 0000000..014aa63
--- /dev/null
+++ b/internal/encoding/ssh/filexfer/openssh/statvfs_test.go
@@ -0,0 +1,239 @@
+package openssh
+
+import (
+	"bytes"
+	"testing"
+
+	sshfx "github.com/pkg/sftp/internal/encoding/ssh/filexfer"
+)
+
+var _ sshfx.PacketMarshaller = &StatVFSExtendedPacket{}
+
+func init() {
+	RegisterExtensionStatVFS()
+}
+
+func TestStatVFSExtendedPacket(t *testing.T) {
+	const (
+		id   = 42
+		path = "/foo"
+	)
+
+	ep := &StatVFSExtendedPacket{
+		Path: path,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 36,
+		200,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 19, 's', 't', 'a', 't', 'v', 'f', 's', '@', 'o', 'p', 'e', 'n', 's', 's', 'h', '.', 'c', 'o', 'm',
+		0x00, 0x00, 0x00, 4, '/', 'f', 'o', 'o',
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	var p sshfx.ExtendedPacket
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	if p.ExtendedRequest != extensionStatVFS {
+		t.Errorf("UnmarshalPacketBody(): ExtendedRequest was %q, but expected %q", p.ExtendedRequest, extensionStatVFS)
+	}
+
+	ep, ok := p.Data.(*StatVFSExtendedPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *StatVFSExtendedPacket", p.Data)
+	}
+
+	if ep.Path != path {
+		t.Errorf("UnmarshalPacketBody(): Path was %q, but expected %q", ep.Path, path)
+	}
+}
+
+var _ sshfx.PacketMarshaller = &FStatVFSExtendedPacket{}
+
+func init() {
+	RegisterExtensionFStatVFS()
+}
+
+func TestFStatVFSExtendedPacket(t *testing.T) {
+	const (
+		id   = 42
+		path = "/foo"
+	)
+
+	ep := &FStatVFSExtendedPacket{
+		Path: path,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 37,
+		200,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 20, 'f', 's', 't', 'a', 't', 'v', 'f', 's', '@', 'o', 'p', 'e', 'n', 's', 's', 'h', '.', 'c', 'o', 'm',
+		0x00, 0x00, 0x00, 4, '/', 'f', 'o', 'o',
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	var p sshfx.ExtendedPacket
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	if p.ExtendedRequest != extensionFStatVFS {
+		t.Errorf("UnmarshalPacketBody(): ExtendedRequest was %q, but expected %q", p.ExtendedRequest, extensionFStatVFS)
+	}
+
+	ep, ok := p.Data.(*FStatVFSExtendedPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *FStatVFSExtendedPacket", p.Data)
+	}
+
+	if ep.Path != path {
+		t.Errorf("UnmarshalPacketBody(): Path was %q, but expected %q", ep.Path, path)
+	}
+}
+
+var _ sshfx.Packet = &StatVFSExtendedReplyPacket{}
+
+func TestStatVFSExtendedReplyPacket(t *testing.T) {
+	const (
+		id   = 42
+		path = "/foo"
+	)
+
+	const (
+		BlockSize = uint64(iota + 13)
+		FragmentSize
+		Blocks
+		BlocksFree
+		BlocksAvail
+		Files
+		FilesFree
+		FilesAvail
+		FilesystemID
+		MountFlags
+		MaxNameLength
+	)
+
+	ep := &StatVFSExtendedReplyPacket{
+		BlockSize:     BlockSize,
+		FragmentSize:  FragmentSize,
+		Blocks:        Blocks,
+		BlocksFree:    BlocksFree,
+		BlocksAvail:   BlocksAvail,
+		Files:         Files,
+		FilesFree:     FilesFree,
+		FilesAvail:    FilesAvail,
+		FilesystemID:  FilesystemID,
+		MountFlags:    MountFlags,
+		MaxNameLength: MaxNameLength,
+	}
+
+	data, err := sshfx.ComposePacket(ep.MarshalPacket(id, nil))
+	if err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	want := []byte{
+		0x00, 0x00, 0x00, 93,
+		201,
+		0x00, 0x00, 0x00, 42,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 13,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 14,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 15,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 16,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 17,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 18,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 19,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 20,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 21,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 22,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 23,
+	}
+
+	if !bytes.Equal(data, want) {
+		t.Fatalf("MarshalPacket() = %X, but wanted %X", data, want)
+	}
+
+	*ep = StatVFSExtendedReplyPacket{}
+
+	p := sshfx.ExtendedReplyPacket{
+		Data: ep,
+	}
+
+	// UnmarshalPacketBody assumes the (length, type, request-id) have already been consumed.
+	if err := p.UnmarshalPacketBody(sshfx.NewBuffer(data[9:])); err != nil {
+		t.Fatal("unexpected error:", err)
+	}
+
+	ep, ok := p.Data.(*StatVFSExtendedReplyPacket)
+	if !ok {
+		t.Fatalf("UnmarshaledPacketBody(): Data was type %T, but expected *StatVFSExtendedReplyPacket", p.Data)
+	}
+
+	if ep.BlockSize != BlockSize {
+		t.Errorf("UnmarshalPacketBody(): BlockSize was %d, but expected %d", ep.BlockSize, BlockSize)
+	}
+
+	if ep.FragmentSize != FragmentSize {
+		t.Errorf("UnmarshalPacketBody(): FragmentSize was %d, but expected %d", ep.FragmentSize, FragmentSize)
+	}
+
+	if ep.Blocks != Blocks {
+		t.Errorf("UnmarshalPacketBody(): Blocks was %d, but expected %d", ep.Blocks, Blocks)
+	}
+
+	if ep.BlocksFree != BlocksFree {
+		t.Errorf("UnmarshalPacketBody(): BlocksFree was %d, but expected %d", ep.BlocksFree, BlocksFree)
+	}
+
+	if ep.BlocksAvail != BlocksAvail {
+		t.Errorf("UnmarshalPacketBody(): BlocksAvail was %d, but expected %d", ep.BlocksAvail, BlocksAvail)
+	}
+
+	if ep.Files != Files {
+		t.Errorf("UnmarshalPacketBody(): Files was %d, but expected %d", ep.Files, Files)
+	}
+
+	if ep.FilesFree != FilesFree {
+		t.Errorf("UnmarshalPacketBody(): FilesFree was %d, but expected %d", ep.FilesFree, FilesFree)
+	}
+
+	if ep.FilesAvail != FilesAvail {
+		t.Errorf("UnmarshalPacketBody(): FilesAvail was %d, but expected %d", ep.FilesAvail, FilesAvail)
+	}
+
+	if ep.FilesystemID != FilesystemID {
+		t.Errorf("UnmarshalPacketBody(): FilesystemID was %d, but expected %d", ep.FilesystemID, FilesystemID)
+	}
+
+	if ep.MountFlags != MountFlags {
+		t.Errorf("UnmarshalPacketBody(): MountFlags was %d, but expected %d", ep.MountFlags, MountFlags)
+	}
+
+	if ep.MaxNameLength != MaxNameLength {
+		t.Errorf("UnmarshalPacketBody(): MaxNameLength was %d, but expected %d", ep.MaxNameLength, MaxNameLength)
+	}
+}