Add support for working directory in Server

This commit allows the working directory for the (old) Server implementation to be changed without doing a `os.Chdir` first. The feature can be enabled with `sftp.WithServerWorkingDirectory(dir)` passed as an option to `sftp.NewServer`. It is useful when the `sftp` is used as part of a larger service that does more than just serve `sftp` and using `os.Chdir` is not an option. The fallback behavior (when the option is not specified) is that the path remains unmodified (as before).
pkg · Oct 14, 2022 · 6a7168c · 6a7168c
1 parent 3aa4378
commit 6a7168c
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Showing 5 changed files with 59 additions and 28 deletions.
diff --git a/packet.go b/packet.go
@@ -1247,7 +1247,7 @@ func (p *sshFxpExtendedPacketPosixRename) UnmarshalBinary(b []byte) error {
 }
 
 func (p *sshFxpExtendedPacketPosixRename) respond(s *Server) responsePacket {
- err := os.Rename(toLocalPath(p.Oldpath), toLocalPath(p.Newpath))
+ err := os.Rename(toLocalPath(s.workDir, p.Oldpath), toLocalPath(s.workDir, p.Newpath))
  return statusFromError(p.ID, err)
 }
 
@@ -1276,6 +1276,6 @@ func (p *sshFxpExtendedPacketHardlink) UnmarshalBinary(b []byte) error {
 }
 
 func (p *sshFxpExtendedPacketHardlink) respond(s *Server) responsePacket {
- err := os.Link(toLocalPath(p.Oldpath), toLocalPath(p.Newpath))
+ err := os.Link(toLocalPath(s.workDir, p.Oldpath), toLocalPath(s.workDir, p.Newpath))
  return statusFromError(p.ID, err)
 }
diff --git a/request-plan9.go b/request-plan9.go
@@ -16,7 +16,15 @@ func testOsSys(sys interface{}) error {
  return nil
 }
 
-func toLocalPath(p string) string {
+func toLocalPath(workDir, p string) string {
+ if workDir != "" {
+ if !filepath.IsAbs(p) && !path.IsAbs(p) {
+ // Ensure input is always in the same format.
+ p = filepath.ToSlash(p)
+ p = path.Join(workDir, p)
+ }
+ }
+
  lp := filepath.FromSlash(p)
 
  if path.IsAbs(p) {
@@ -28,6 +36,7 @@ func toLocalPath(p string) string {
  // e.g. "/#s/boot" to "#s/boot"
  return tmp
  }
+
  }
 
  return lp

diff --git a/request-unix.go b/request-unix.go
@@ -4,6 +4,8 @@ package sftp
 
 import (
  "errors"
+ "path"
+ "path/filepath"
  "syscall"
 )
 
@@ -22,6 +24,14 @@ func testOsSys(sys interface{}) error {
  return nil
 }
 
-func toLocalPath(p string) string {
+func toLocalPath(workDir, p string) string {
+ if workDir != "" {
+ if !filepath.IsAbs(p) && !path.IsAbs(p) {
+ // Ensure input is always in the same format.
+ p = filepath.ToSlash(p)
+ p = path.Join(workDir, p)
+ }
+ }
+
  return p
 }
diff --git a/request_windows.go b/request_windows.go
@@ -14,7 +14,15 @@ func testOsSys(sys interface{}) error {
  return nil
 }
 
-func toLocalPath(p string) string {
+func toLocalPath(workDir, p string) string {
+ if workDir != "" {
+ if !filepath.IsAbs(p) && !path.IsAbs(p) {
+ // Ensure input is always in the same format.
+ p = filepath.ToSlash(p)
+ p = path.Join(workDir, p)
+ }
+ }
+
  lp := filepath.FromSlash(p)
 
  if path.IsAbs(p) {
@@ -38,6 +46,7 @@ func toLocalPath(p string) string {
  // e.g. "/C:" to "C:\\"
  return tmp
  }
+
  }
 
  return lp

diff --git a/server.go b/server.go
@@ -33,6 +33,7 @@ type Server struct {
  openFiles map[string]*os.File
  openFilesLock sync.RWMutex
  handleCount int
+ workDir string
 }
 
 func (svr *Server) nextHandle(f *os.File) string {
@@ -128,6 +129,16 @@ func WithAllocator() ServerOption {
  }
 }
 
+// WithServerWorkingDirectory sets a working directory to use as base
+// for relative paths.
+// If unset the default is current working directory (os.Getwd).
+func WithServerWorkingDirectory(workDir string) ServerOption {
+ return func(s *Server) error {
+ s.workDir = cleanPath(workDir)
+ return nil
+ }
+}
+
 type rxPacket struct {
  pktType fxp
  pktBytes []byte
@@ -174,7 +185,7 @@ func handlePacket(s *Server, p orderedRequest) error {
  }
  case *sshFxpStatPacket:
  // stat the requested file
- info, err := os.Stat(toLocalPath(p.Path))
+ info, err := os.Stat(toLocalPath(s.workDir, p.Path))
  rpkt = &sshFxpStatResponse{
  ID: p.ID,
  info: info,
@@ -184,7 +195,7 @@ func handlePacket(s *Server, p orderedRequest) error {
  }
  case *sshFxpLstatPacket:
  // stat the requested file
- info, err := os.Lstat(toLocalPath(p.Path))
+ info, err := os.Lstat(toLocalPath(s.workDir, p.Path))
  rpkt = &sshFxpStatResponse{
  ID: p.ID,
  info: info,
@@ -208,24 +219,24 @@ func handlePacket(s *Server, p orderedRequest) error {
  }
  case *sshFxpMkdirPacket:
  // TODO FIXME: ignore flags field
- err := os.Mkdir(toLocalPath(p.Path), 0755)
+ err := os.Mkdir(toLocalPath(s.workDir, p.Path), 0o755)
  rpkt = statusFromError(p.ID, err)
  case *sshFxpRmdirPacket:
- err := os.Remove(toLocalPath(p.Path))
+ err := os.Remove(toLocalPath(s.workDir, p.Path))
  rpkt = statusFromError(p.ID, err)
  case *sshFxpRemovePacket:
- err := os.Remove(toLocalPath(p.Filename))
+ err := os.Remove(toLocalPath(s.workDir, p.Filename))
  rpkt = statusFromError(p.ID, err)
  case *sshFxpRenamePacket:
- err := os.Rename(toLocalPath(p.Oldpath), toLocalPath(p.Newpath))
+ err := os.Rename(toLocalPath(s.workDir, p.Oldpath), toLocalPath(s.workDir, p.Newpath))
  rpkt = statusFromError(p.ID, err)
  case *sshFxpSymlinkPacket:
- err := os.Symlink(toLocalPath(p.Targetpath), toLocalPath(p.Linkpath))
+ err := os.Symlink(toLocalPath(s.workDir, p.Targetpath), toLocalPath(s.workDir, p.Linkpath))
  rpkt = statusFromError(p.ID, err)
  case *sshFxpClosePacket:
  rpkt = statusFromError(p.ID, s.closeHandle(p.Handle))
  case *sshFxpReadlinkPacket:
- f, err := os.Readlink(toLocalPath(p.Path))
+ f, err := os.Readlink(toLocalPath(s.workDir, p.Path))
  rpkt = &sshFxpNamePacket{
  ID: p.ID,
  NameAttrs: []*sshFxpNameAttr{
@@ -240,29 +251,21 @@ func handlePacket(s *Server, p orderedRequest) error {
  rpkt = statusFromError(p.ID, err)
  }
  case *sshFxpRealpathPacket:
- f, err := filepath.Abs(toLocalPath(p.Path))
+ f, err := filepath.Abs(toLocalPath(s.workDir, p.Path))
  f = cleanPath(f)
- rpkt = &sshFxpNamePacket{
- ID: p.ID,
- NameAttrs: []*sshFxpNameAttr{
- {
- Name: f,
- LongName: f,
- Attrs: emptyFileStat,
- },
- },
- }
+ rpkt = cleanPacketPath(p, f)
  if err != nil {
  rpkt = statusFromError(p.ID, err)
  }
  case *sshFxpOpendirPacket:
- p.Path = toLocalPath(p.Path)
+ p.Path = toLocalPath(s.workDir, p.Path)
 
  if stat, err := os.Stat(p.Path); err != nil {
  rpkt = statusFromError(p.ID, err)
  } else if !stat.IsDir() {
  rpkt = statusFromError(p.ID, &os.PathError{
- Path: p.Path, Err: syscall.ENOTDIR})
+ Path: p.Path, Err: syscall.ENOTDIR,
+ })
  } else {
  rpkt = (&sshFxpOpenPacket{
  ID: p.ID,
@@ -446,7 +449,7 @@ func (p *sshFxpOpenPacket) respond(svr *Server) responsePacket {
  osFlags |= os.O_EXCL
  }
 
- f, err := os.OpenFile(toLocalPath(p.Path), osFlags, 0644)
+ f, err := os.OpenFile(toLocalPath(svr.workDir, p.Path), osFlags, 0o644)
  if err != nil {
  return statusFromError(p.ID, err)
  }
@@ -484,7 +487,7 @@ func (p *sshFxpSetstatPacket) respond(svr *Server) responsePacket {
  b := p.Attrs.([]byte)
  var err error
 
- p.Path = toLocalPath(p.Path)
+ p.Path = toLocalPath(svr.workDir, p.Path)
 
  debug("setstat name \"%s\"", p.Path)
  if (p.Flags & sshFileXferAttrSize) != 0 {