ssh/sftp: make the package compatible with standard fs package

List of changes,

* Rename Node type to dirEntry and implement fs.DirEntry on it
* Change the Client Readdir, Readlink, and Realpath to return fs.DirEntry
* Make the response packet garbage collected by storing the result
  in returned type and setting the response packet fields to nil
* Add field name to FileAttrs, which store the remote file name
* Implement fs.FileInfo interface in FileAttrs
* Store the remote path on FileHandle

8 files changed, 210 insertions, 48 deletions

diff --git a/lib/ssh/sftp/client.go b/lib/ssh/sftp/client.go
index babd1dfa..bf61c347 100644
--- a/lib/ssh/sftp/client.go
+++ b/lib/ssh/sftp/client.go
@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"sync"
 	"time"
@@ -157,8 +158,10 @@ func (cl *Client) Fstat(fh *FileHandle) (fa *FileAttrs, err error) {
 	if res.kind != packetKindFxpAttrs {
 		return nil, ErrUnexpectedResponse(packetKindFxpAttrs, res.kind)
 	}
-
-	return res.fa, nil
+	fa = res.fa
+	fa.name = fh.remotePath
+	res.fa = nil
+	return fa, nil
 }
 
 //
@@ -232,8 +235,10 @@ func (cl *Client) Lstat(remoteFile string) (fa *FileAttrs, err error) {
 	if res.kind != packetKindFxpAttrs {
 		return nil, ErrUnexpectedResponse(packetKindFxpAttrs, res.kind)
 	}
-
-	return res.fa, nil
+	fa = res.fa
+	fa.name = remoteFile
+	res.fa = nil
+	return fa, nil
 }
 
 //
@@ -289,6 +294,7 @@ func (cl *Client) Opendir(path string) (fh *FileHandle, err error) {
 		return nil, ErrUnexpectedResponse(packetKindFxpHandle, res.kind)
 	}
 	fh = res.fh
+	fh.remotePath = path
 	res.fh = nil
 	return fh, nil
 }
@@ -375,14 +381,15 @@ func (cl *Client) Read(fh *FileHandle, offset uint64) (data []byte, err error) {
 	if res.kind != packetKindFxpData {
 		return nil, ErrUnexpectedResponse(packetKindFxpData, res.kind)
 	}
-
-	return res.data, nil
+	data = res.data
+	res.data = nil
+	return data, nil
 }
 
 //
 // Readdir list files and/or directories inside the handle.
 //
-func (cl *Client) Readdir(fh *FileHandle) (nodes []*Node, err error) {
+func (cl *Client) Readdir(fh *FileHandle) (nodes []fs.DirEntry, err error) {
 	var (
 		logp    = "Readdir"
 		req     = cl.generatePacket()
@@ -400,7 +407,9 @@ func (cl *Client) Readdir(fh *FileHandle) (nodes []*Node, err error) {
 	if res.kind != packetKindFxpName {
 		return nil, ErrUnexpectedResponse(packetKindFxpName, res.kind)
 	}
-	nodes = res.nodes
+	for _, node := range res.nodes {
+		nodes = append(nodes, node)
+	}
 	res.nodes = nil
 	return nodes, nil
 }
@@ -408,7 +417,7 @@ func (cl *Client) Readdir(fh *FileHandle) (nodes []*Node, err error) {
 //
 // Readlink read the target of a symbolic link.
 //
-func (cl *Client) Readlink(linkPath string) (node *Node, err error) {
+func (cl *Client) Readlink(linkPath string) (node fs.DirEntry, err error) {
 	var (
 		logp    = "Readlink"
 		req     = cl.generatePacket()
@@ -422,8 +431,9 @@ func (cl *Client) Readlink(linkPath string) (node *Node, err error) {
 	if res.kind != packetKindFxpName {
 		return nil, ErrUnexpectedResponse(packetKindFxpName, res.kind)
 	}
-
-	return res.nodes[0], nil
+	node = res.nodes[0]
+	res.nodes = nil
+	return node, nil
 }
 
 //
@@ -431,7 +441,7 @@ func (cl *Client) Readlink(linkPath string) (node *Node, err error) {
 // This is useful for converting path names containing ".." components or
 // relative pathnames without a leading slash into absolute paths.
 //
-func (cl *Client) Realpath(path string) (node *Node, err error) {
+func (cl *Client) Realpath(path string) (node fs.DirEntry, err error) {
 	var (
 		logp    = "Realpath"
 		req     = cl.generatePacket()
@@ -445,8 +455,9 @@ func (cl *Client) Realpath(path string) (node *Node, err error) {
 	if res.kind != packetKindFxpName {
 		return nil, ErrUnexpectedResponse(packetKindFxpName, res.kind)
 	}
-
-	return res.nodes[0], nil
+	node = res.nodes[0]
+	res.nodes = nil
+	return node, nil
 }
 
 //
@@ -572,8 +583,10 @@ func (cl *Client) Stat(remoteFile string) (fa *FileAttrs, err error) {
 	if res.kind != packetKindFxpAttrs {
 		return nil, ErrUnexpectedResponse(packetKindFxpAttrs, res.kind)
 	}
-
-	return res.fa, nil
+	fa = res.fa
+	fa.name = remoteFile
+	res.fa = nil
+	return fa, nil
 }
 
 //
@@ -654,7 +667,7 @@ func (cl *Client) init() (err error) {
 	return nil
 }
 
-func (cl *Client) open(remoteFile string, pflags uint32, fa *FileAttrs) (h *FileHandle, err error) {
+func (cl *Client) open(remoteFile string, pflags uint32, fa *FileAttrs) (fh *FileHandle, err error) {
 	var (
 		logp = "open"
 		req  = cl.generatePacket()
@@ -674,8 +687,10 @@ func (cl *Client) open(remoteFile string, pflags uint32, fa *FileAttrs) (h *File
 		err = fmt.Errorf("%s: %d %d %s", logp, res.kind, res.code, res.message)
 		return nil, err
 	}
-
-	return res.fh, nil
+	fh = res.fh
+	fh.remotePath = remoteFile
+	res.fh = nil
+	return fh, nil
 }
 
 func (cl *Client) read() (res []byte, err error) {
diff --git a/lib/ssh/sftp/client_test.go b/lib/ssh/sftp/client_test.go
index aed7ddd7..79d1d4e7 100644
--- a/lib/ssh/sftp/client_test.go
+++ b/lib/ssh/sftp/client_test.go
@@ -70,7 +70,7 @@ func TestClient_Get(t *testing.T) {
 		t.Skipf("%s not set", envNameTestManual)
 	}
 
-	err := testClient.Get("/tmp/id_ed25519.pub", "testdata/id_ed25519.pub.get")
+	err := testClient.Get("/etc/hosts", "testdata/etc-hosts.get")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -136,7 +136,8 @@ func TestClient_Readdir(t *testing.T) {
 
 	t.Logf("List of files inside the %s:\n", path)
 	for x, node := range nodes {
-		t.Logf("%02d: %+v\n", x, node.LongName)
+		fi, _ := node.Info()
+		t.Logf("%02d: %s %+v\n", x, fi.Mode().String(), node.Name())
 	}
 }
 
@@ -151,7 +152,7 @@ func TestClient_Realpath(t *testing.T) {
 	}
 
 	exp := "/etc/hosts"
-	test.Assert(t, "Realpath", exp, node.FileName)
+	test.Assert(t, "Realpath", exp, node.Name())
 }
 
 func TestClient_Rename(t *testing.T) {
@@ -189,6 +190,8 @@ func TestClient_Rename(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	expAttrs.name = newPath
+
 	test.Assert(t, "Rename", expAttrs, gotAttrs)
 }
 
@@ -277,5 +280,5 @@ func TestClient_Symlink(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	test.Assert(t, "Readlink", targetPath, node.FileName)
+	test.Assert(t, "Readlink", targetPath, node.Name())
 }
diff --git a/lib/ssh/sftp/dir_entry.go b/lib/ssh/sftp/dir_entry.go
new file mode 100644
index 00000000..fe41cf5d
--- /dev/null
+++ b/lib/ssh/sftp/dir_entry.go
@@ -0,0 +1,33 @@
+// Copyright 2021, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sftp
+
+import "os"
+
+//
+// dirEntry represent the internal data returned from Readdir, Readlink, or
+// Realpath.
+//
+type dirEntry struct {
+	fileName string
+	longName string
+	attrs    *FileAttrs
+}
+
+func (de *dirEntry) Name() string {
+	return de.fileName
+}
+
+func (de *dirEntry) IsDir() bool {
+	return de.attrs.IsDir()
+}
+
+func (de *dirEntry) Type() os.FileMode {
+	return os.FileMode(de.attrs.permissions & fileTypeMask)
+}
+
+func (de *dirEntry) Info() (os.FileInfo, error) {
+	return de.attrs, nil
+}
diff --git a/lib/ssh/sftp/file_attrs.go b/lib/ssh/sftp/file_attrs.go
index a7c14e21..28c73381 100644
--- a/lib/ssh/sftp/file_attrs.go
+++ b/lib/ssh/sftp/file_attrs.go
@@ -8,6 +8,21 @@ import (
 	"encoding/binary"
 	"io"
 	"io/fs"
+	"time"
+)
+
+const (
+	fileModeSticky      uint32 = 0001000
+	fileModeSetgid      uint32 = 0002000
+	fileModeSetuid      uint32 = 0004000
+	fileTypeFifo        uint32 = 0010000
+	fileTypeCharDevice  uint32 = 0020000
+	fileTypeDirectory   uint32 = 0040000
+	fileTypeBlockDevice uint32 = 0060000
+	fileTypeRegular     uint32 = 0100000
+	fileTypeSymlink     uint32 = 0120000
+	fileTypeSocket      uint32 = 0140000
+	fileTypeMask        uint32 = 0170000
 )
 
 // List of valid values for FileAttrs.flags.
@@ -23,6 +38,7 @@ const (
 // FileAttrs define the attributes for opening or creating file on the remote.
 //
 type FileAttrs struct {
+	name        string
 	flags       uint32
 	size        uint64     // attr_SIZE
 	uid         uint32     // attr_UIDGID
@@ -31,13 +47,16 @@ type FileAttrs struct {
 	atime       uint32     // attr_ACMODTIME
 	mtime       uint32     // attr_ACMODTIME
 	exts        extensions // attr_EXTENDED
+	fsMode      fs.FileMode
 }
 
 //
 // NewFileAttrs create and initialize FileAttrs from FileInfo.
 //
 func NewFileAttrs(fi fs.FileInfo) (fa *FileAttrs) {
-	fa = &FileAttrs{}
+	fa = &FileAttrs{
+		name: fi.Name(),
+	}
 
 	mode := fi.Mode()
 	mtime := fi.ModTime()
@@ -77,6 +96,7 @@ func unpackFileAttrs(payload []byte) (fa *FileAttrs, length int) {
 		fa.permissions = binary.BigEndian.Uint32(payload)
 		payload = payload[4:]
 		length += 4
+		fa.updateFsmode()
 	}
 	if fa.flags&attr_ACMODTIME != 0 {
 		fa.atime = binary.BigEndian.Uint32(payload)
@@ -167,14 +187,32 @@ func (fa *FileAttrs) Gid() uint32 {
 }
 
 //
-// AccessTime return the remote file modified time.
+// IsDir return true if the file is a directory.
+//
+func (fa *FileAttrs) IsDir() bool {
+	return fa.fsMode.IsDir()
+}
+
 //
-func (fa *FileAttrs) ModifiedTime() uint32 {
-	return fa.mtime
+// ModTime return the remote file modified time.
+//
+func (fa *FileAttrs) ModTime() time.Time {
+	return time.Unix(int64(fa.mtime), 0)
+}
+
+//
+// Mode return the file mode bits as standard fs.FileMode type.
+//
+func (fa *FileAttrs) Mode() fs.FileMode {
+	return fa.fsMode
+}
+
+func (fa *FileAttrs) Name() string {
+	return fa.name
 }
 
 //
-// Permissions return the remote file permissions.
+// Permissions return the remote file mode and permissions.
 //
 func (fa *FileAttrs) Permissions() uint32 {
 	return fa.permissions
@@ -221,6 +259,7 @@ func (fa *FileAttrs) SetModifiedTime(v uint32) {
 func (fa *FileAttrs) SetPermissions(v uint32) {
 	fa.flags |= attr_PERMISSIONS
 	fa.permissions = v
+	fa.updateFsmode()
 }
 
 //
@@ -240,8 +279,51 @@ func (fa *FileAttrs) SetUid(uid uint32) {
 }
 
 //
+// Size return the file size information.
+//
+func (fa *FileAttrs) Size() int64 {
+	return int64(fa.size)
+}
+
+//
+// Sys return the pointer to FileAttrs itself.
+//
+func (fa *FileAttrs) Sys() interface{} {
+	return fa
+}
+
+//
 // Uid return the user ID of file.
 //
 func (fa *FileAttrs) Uid() uint32 {
 	return fa.uid
 }
+
+func (fa *FileAttrs) updateFsmode() {
+	fa.fsMode = fs.FileMode(fa.permissions & 0777)
+	switch fa.permissions & fileTypeMask {
+	case fileTypeFifo:
+		fa.fsMode |= fs.ModeNamedPipe
+	case fileTypeCharDevice:
+		fa.fsMode |= fs.ModeDevice | fs.ModeCharDevice
+	case fileTypeDirectory:
+		fa.fsMode |= fs.ModeDir
+	case fileTypeBlockDevice:
+		fa.fsMode |= fs.ModeDevice
+	case fileTypeRegular:
+		// NOOP
+	case fileTypeSymlink:
+		fa.fsMode |= fs.ModeSymlink
+	case fileTypeSocket:
+		fa.fsMode |= fs.ModeSocket
+	}
+	if fa.permissions&fileModeSetgid != 0 {
+		fa.fsMode |= fs.ModeSetgid
+	}
+	if fa.permissions&fileModeSetuid != 0 {
+		fa.fsMode |= fs.ModeSetuid
+	}
+	if fa.permissions&fileModeSticky != 0 {
+		fa.fsMode |= fs.ModeSticky
+	}
+}
diff --git a/lib/ssh/sftp/file_attrs_test.go b/lib/ssh/sftp/file_attrs_test.go
new file mode 100644
index 00000000..95bf893b
--- /dev/null
+++ b/lib/ssh/sftp/file_attrs_test.go
@@ -0,0 +1,42 @@
+// Copyright 2021, Shulhan <ms@kilabit.info>. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sftp
+
+import (
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/shuLhan/share/lib/test"
+)
+
+func TestFileAttrs_Mode(t *testing.T) {
+	if !isTestManual {
+		t.Skipf("%s not set", envNameTestManual)
+	}
+
+	cases := []struct {
+		path string
+	}{{
+		path: "/etc",
+	}, {
+		path: "/etc/hosts",
+	}}
+
+	for _, c := range cases {
+		exp, err := fs.Stat(os.DirFS(filepath.Dir(c.path)), filepath.Base(c.path))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		got, err := testClient.Stat(c.path)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		test.Assert(t, "Stat", exp.Mode(), got.Mode())
+	}
+}
diff --git a/lib/ssh/sftp/file_handle.go b/lib/ssh/sftp/file_handle.go
index 36467188..71c4ed81 100644
--- a/lib/ssh/sftp/file_handle.go
+++ b/lib/ssh/sftp/file_handle.go
@@ -5,5 +5,6 @@
 package sftp
 
 type FileHandle struct {
-	v []byte
+	remotePath string // The remote path.
+	v          []byte // The handle value returned from open().
 }
diff --git a/lib/ssh/sftp/node.go b/lib/ssh/sftp/node.go
deleted file mode 100644
index dc038d9b..00000000
--- a/lib/ssh/sftp/node.go
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright 2021, Shulhan <ms@kilabit.info>. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package sftp
-
-//
-// Node represent the data returned from Readlink.
-//
-type Node struct {
-	FileName string
-	LongName string
-	Attrs    *FileAttrs
-}
diff --git a/lib/ssh/sftp/packet.go b/lib/ssh/sftp/packet.go
index 93a658d8..99299e0e 100644
--- a/lib/ssh/sftp/packet.go
+++ b/lib/ssh/sftp/packet.go
@@ -65,7 +65,7 @@ type packet struct {
 	data []byte
 
 	// FxpName
-	nodes []*Node
+	nodes []*dirEntry
 
 	// FxpAttrs
 	fa *FileAttrs
@@ -131,19 +131,19 @@ func unpackPacket(payload []byte) (pac *packet, err error) {
 		n := binary.BigEndian.Uint32(payload)
 		payload = payload[4:]
 		for x := uint32(0); x < n; x++ {
-			node := &Node{}
+			node := &dirEntry{}
 
 			v = binary.BigEndian.Uint32(payload)
 			payload = payload[4:]
-			node.FileName = string(payload[:v])
+			node.fileName = string(payload[:v])
 			payload = payload[v:]
 
 			v = binary.BigEndian.Uint32(payload)
 			payload = payload[4:]
-			node.LongName = string(payload[:v])
+			node.longName = string(payload[:v])
 			payload = payload[v:]
 
-			node.Attrs, length = unpackFileAttrs(payload)
+			node.attrs, length = unpackFileAttrs(payload)
 			payload = payload[length:]
 
 			pac.nodes = append(pac.nodes, node)