package sftp import ( "bytes" "encoding/binary" "io" "os" "path" "sync/atomic" "time" "github.com/kr/fs" "github.com/pkg/errors" "golang.org/x/crypto/ssh" ) // MaxPacket sets the maximum size of the payload. func MaxPacket(size int) func(*Client) error { return func(c *Client) error { if size < 1<<15 { return errors.Errorf("size must be greater or equal to 32k") } c.maxPacket = size return nil } } // NewClient creates a new SFTP client on conn, using zero or more option // functions. func NewClient(conn *ssh.Client, opts ...func(*Client) error) (*Client, error) { s, err := conn.NewSession() if err != nil { return nil, err } if err := s.RequestSubsystem("sftp"); err != nil { return nil, err } pw, err := s.StdinPipe() if err != nil { return nil, err } pr, err := s.StdoutPipe() if err != nil { return nil, err } return NewClientPipe(pr, pw, opts...) } // NewClientPipe creates a new SFTP client given a Reader and a WriteCloser. // This can be used for connecting to an SFTP server over TCP/TLS or by using // the system's ssh client program (e.g. via exec.Command). func NewClientPipe(rd io.Reader, wr io.WriteCloser, opts ...func(*Client) error) (*Client, error) { sftp := &Client{ clientConn: clientConn{ conn: conn{ Reader: rd, WriteCloser: wr, }, inflight: make(map[uint32]chan<- result), }, maxPacket: 1 << 15, } if err := sftp.applyOptions(opts...); err != nil { wr.Close() return nil, err } if err := sftp.sendInit(); err != nil { wr.Close() return nil, err } if err := sftp.recvVersion(); err != nil { wr.Close() return nil, err } sftp.clientConn.wg.Add(1) go sftp.loop() return sftp, nil } // Client represents an SFTP session on a *ssh.ClientConn SSH connection. // Multiple Clients can be active on a single SSH connection, and a Client // may be called concurrently from multiple Goroutines. // // Client implements the github.com/kr/fs.FileSystem interface. type Client struct { clientConn maxPacket int // max packet size read or written. nextid uint32 } // Create creates the named file mode 0666 (before umask), truncating it if // it already exists. If successful, methods on the returned File can be // used for I/O; the associated file descriptor has mode O_RDWR. func (c *Client) Create(path string) (*File, error) { return c.open(path, flags(os.O_RDWR|os.O_CREATE|os.O_TRUNC)) } const sftpProtocolVersion = 3 // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-02 func (c *Client) sendInit() error { return c.clientConn.conn.sendPacket(sshFxInitPacket{ Version: sftpProtocolVersion, // http://tools.ietf.org/html/draft-ietf-secsh-filexfer-02 }) } // returns the next value of c.nextid func (c *Client) nextID() uint32 { return atomic.AddUint32(&c.nextid, 1) } func (c *Client) recvVersion() error { typ, data, err := c.recvPacket() if err != nil { return err } if typ != ssh_FXP_VERSION { return &unexpectedPacketErr{ssh_FXP_VERSION, typ} } version, _ := unmarshalUint32(data) if version != sftpProtocolVersion { return &unexpectedVersionErr{sftpProtocolVersion, version} } return nil } // Walk returns a new Walker rooted at root. func (c *Client) Walk(root string) *fs.Walker { return fs.WalkFS(root, c) } // ReadDir reads the directory named by dirname and returns a list of // directory entries. func (c *Client) ReadDir(p string) ([]os.FileInfo, error) { handle, err := c.opendir(p) if err != nil { return nil, err } defer c.close(handle) // this has to defer earlier than the lock below var attrs []os.FileInfo var done = false for !done { id := c.nextID() typ, data, err1 := c.sendPacket(sshFxpReaddirPacket{ ID: id, Handle: handle, }) if err1 != nil { err = err1 done = true break } switch typ { case ssh_FXP_NAME: sid, data := unmarshalUint32(data) if sid != id { return nil, &unexpectedIDErr{id, sid} } count, data := unmarshalUint32(data) for i := uint32(0); i < count; i++ { var filename string filename, data = unmarshalString(data) _, data = unmarshalString(data) // discard longname var attr *FileStat attr, data = unmarshalAttrs(data) if filename == "." || filename == ".." { continue } attrs = append(attrs, fileInfoFromStat(attr, path.Base(filename))) } case ssh_FXP_STATUS: // TODO(dfc) scope warning! err = normaliseError(unmarshalStatus(id, data)) done = true default: return nil, unimplementedPacketErr(typ) } } if err == io.EOF { err = nil } return attrs, err } func (c *Client) opendir(path string) (string, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpOpendirPacket{ ID: id, Path: path, }) if err != nil { return "", err } switch typ { case ssh_FXP_HANDLE: sid, data := unmarshalUint32(data) if sid != id { return "", &unexpectedIDErr{id, sid} } handle, _ := unmarshalString(data) return handle, nil case ssh_FXP_STATUS: return "", unmarshalStatus(id, data) default: return "", unimplementedPacketErr(typ) } } // Stat returns a FileInfo structure describing the file specified by path 'p'. // If 'p' is a symbolic link, the returned FileInfo structure describes the referent file. func (c *Client) Stat(p string) (os.FileInfo, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpStatPacket{ ID: id, Path: p, }) if err != nil { return nil, err } switch typ { case ssh_FXP_ATTRS: sid, data := unmarshalUint32(data) if sid != id { return nil, &unexpectedIDErr{id, sid} } attr, _ := unmarshalAttrs(data) return fileInfoFromStat(attr, path.Base(p)), nil case ssh_FXP_STATUS: return nil, normaliseError(unmarshalStatus(id, data)) default: return nil, unimplementedPacketErr(typ) } } // Lstat returns a FileInfo structure describing the file specified by path 'p'. // If 'p' is a symbolic link, the returned FileInfo structure describes the symbolic link. func (c *Client) Lstat(p string) (os.FileInfo, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpLstatPacket{ ID: id, Path: p, }) if err != nil { return nil, err } switch typ { case ssh_FXP_ATTRS: sid, data := unmarshalUint32(data) if sid != id { return nil, &unexpectedIDErr{id, sid} } attr, _ := unmarshalAttrs(data) return fileInfoFromStat(attr, path.Base(p)), nil case ssh_FXP_STATUS: return nil, normaliseError(unmarshalStatus(id, data)) default: return nil, unimplementedPacketErr(typ) } } // ReadLink reads the target of a symbolic link. func (c *Client) ReadLink(p string) (string, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpReadlinkPacket{ ID: id, Path: p, }) if err != nil { return "", err } switch typ { case ssh_FXP_NAME: sid, data := unmarshalUint32(data) if sid != id { return "", &unexpectedIDErr{id, sid} } count, data := unmarshalUint32(data) if count != 1 { return "", unexpectedCount(1, count) } filename, _ := unmarshalString(data) // ignore dummy attributes return filename, nil case ssh_FXP_STATUS: return "", unmarshalStatus(id, data) default: return "", unimplementedPacketErr(typ) } } // Symlink creates a symbolic link at 'newname', pointing at target 'oldname' func (c *Client) Symlink(oldname, newname string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpSymlinkPacket{ ID: id, Linkpath: newname, Targetpath: oldname, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } // setstat is a convience wrapper to allow for changing of various parts of the file descriptor. func (c *Client) setstat(path string, flags uint32, attrs interface{}) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpSetstatPacket{ ID: id, Path: path, Flags: flags, Attrs: attrs, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } // Chtimes changes the access and modification times of the named file. func (c *Client) Chtimes(path string, atime time.Time, mtime time.Time) error { type times struct { Atime uint32 Mtime uint32 } attrs := times{uint32(atime.Unix()), uint32(mtime.Unix())} return c.setstat(path, ssh_FILEXFER_ATTR_ACMODTIME, attrs) } // Chown changes the user and group owners of the named file. func (c *Client) Chown(path string, uid, gid int) error { type owner struct { UID uint32 GID uint32 } attrs := owner{uint32(uid), uint32(gid)} return c.setstat(path, ssh_FILEXFER_ATTR_UIDGID, attrs) } // Chmod changes the permissions of the named file. func (c *Client) Chmod(path string, mode os.FileMode) error { return c.setstat(path, ssh_FILEXFER_ATTR_PERMISSIONS, uint32(mode)) } // Truncate sets the size of the named file. Although it may be safely assumed // that if the size is less than its current size it will be truncated to fit, // the SFTP protocol does not specify what behavior the server should do when setting // size greater than the current size. func (c *Client) Truncate(path string, size int64) error { return c.setstat(path, ssh_FILEXFER_ATTR_SIZE, uint64(size)) } // Open opens the named file for reading. If successful, methods on the // returned file can be used for reading; the associated file descriptor // has mode O_RDONLY. func (c *Client) Open(path string) (*File, error) { return c.open(path, flags(os.O_RDONLY)) } // OpenFile is the generalized open call; most users will use Open or // Create instead. It opens the named file with specified flag (O_RDONLY // etc.). If successful, methods on the returned File can be used for I/O. func (c *Client) OpenFile(path string, f int) (*File, error) { return c.open(path, flags(f)) } func (c *Client) open(path string, pflags uint32) (*File, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpOpenPacket{ ID: id, Path: path, Pflags: pflags, }) if err != nil { return nil, err } switch typ { case ssh_FXP_HANDLE: sid, data := unmarshalUint32(data) if sid != id { return nil, &unexpectedIDErr{id, sid} } handle, _ := unmarshalString(data) return &File{c: c, path: path, handle: handle}, nil case ssh_FXP_STATUS: return nil, normaliseError(unmarshalStatus(id, data)) default: return nil, unimplementedPacketErr(typ) } } // close closes a handle handle previously returned in the response // to SSH_FXP_OPEN or SSH_FXP_OPENDIR. The handle becomes invalid // immediately after this request has been sent. func (c *Client) close(handle string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpClosePacket{ ID: id, Handle: handle, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } func (c *Client) fstat(handle string) (*FileStat, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpFstatPacket{ ID: id, Handle: handle, }) if err != nil { return nil, err } switch typ { case ssh_FXP_ATTRS: sid, data := unmarshalUint32(data) if sid != id { return nil, &unexpectedIDErr{id, sid} } attr, _ := unmarshalAttrs(data) return attr, nil case ssh_FXP_STATUS: return nil, unmarshalStatus(id, data) default: return nil, unimplementedPacketErr(typ) } } // StatVFS retrieves VFS statistics from a remote host. // // It implements the statvfs@openssh.com SSH_FXP_EXTENDED feature // from http://www.opensource.apple.com/source/OpenSSH/OpenSSH-175/openssh/PROTOCOL?txt. func (c *Client) StatVFS(path string) (*StatVFS, error) { // send the StatVFS packet to the server id := c.nextID() typ, data, err := c.sendPacket(sshFxpStatvfsPacket{ ID: id, Path: path, }) if err != nil { return nil, err } switch typ { // server responded with valid data case ssh_FXP_EXTENDED_REPLY: var response StatVFS err = binary.Read(bytes.NewReader(data), binary.BigEndian, &response) if err != nil { return nil, errors.New("can not parse reply") } return &response, nil // the resquest failed case ssh_FXP_STATUS: return nil, errors.New(fxp(ssh_FXP_STATUS).String()) default: return nil, unimplementedPacketErr(typ) } } // Join joins any number of path elements into a single path, adding a // separating slash if necessary. The result is Cleaned; in particular, all // empty strings are ignored. func (c *Client) Join(elem ...string) string { return path.Join(elem...) } // Remove removes the specified file or directory. An error will be returned if no // file or directory with the specified path exists, or if the specified directory // is not empty. func (c *Client) Remove(path string) error { err := c.removeFile(path) if err, ok := err.(*StatusError); ok { switch err.Code { // some servers, *cough* osx *cough*, return EPERM, not ENODIR. // serv-u returns ssh_FX_FILE_IS_A_DIRECTORY case ssh_FX_PERMISSION_DENIED, ssh_FX_FAILURE, ssh_FX_FILE_IS_A_DIRECTORY: return c.removeDirectory(path) } } return err } func (c *Client) removeFile(path string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpRemovePacket{ ID: id, Filename: path, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } func (c *Client) removeDirectory(path string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpRmdirPacket{ ID: id, Path: path, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } // Rename renames a file. func (c *Client) Rename(oldname, newname string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpRenamePacket{ ID: id, Oldpath: oldname, Newpath: newname, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } func (c *Client) realpath(path string) (string, error) { id := c.nextID() typ, data, err := c.sendPacket(sshFxpRealpathPacket{ ID: id, Path: path, }) if err != nil { return "", err } switch typ { case ssh_FXP_NAME: sid, data := unmarshalUint32(data) if sid != id { return "", &unexpectedIDErr{id, sid} } count, data := unmarshalUint32(data) if count != 1 { return "", unexpectedCount(1, count) } filename, _ := unmarshalString(data) // ignore attributes return filename, nil case ssh_FXP_STATUS: return "", normaliseError(unmarshalStatus(id, data)) default: return "", unimplementedPacketErr(typ) } } // Getwd returns the current working directory of the server. Operations // involving relative paths will be based at this location. func (c *Client) Getwd() (string, error) { return c.realpath(".") } // Mkdir creates the specified directory. An error will be returned if a file or // directory with the specified path already exists, or if the directory's // parent folder does not exist (the method cannot create complete paths). func (c *Client) Mkdir(path string) error { id := c.nextID() typ, data, err := c.sendPacket(sshFxpMkdirPacket{ ID: id, Path: path, }) if err != nil { return err } switch typ { case ssh_FXP_STATUS: return normaliseError(unmarshalStatus(id, data)) default: return unimplementedPacketErr(typ) } } // applyOptions applies options functions to the Client. // If an error is encountered, option processing ceases. func (c *Client) applyOptions(opts ...func(*Client) error) error { for _, f := range opts { if err := f(c); err != nil { return err } } return nil } // File represents a remote file. type File struct { c *Client path string handle string offset uint64 // current offset within remote file } // Close closes the File, rendering it unusable for I/O. It returns an // error, if any. func (f *File) Close() error { return f.c.close(f.handle) } // Name returns the name of the file as presented to Open or Create. func (f *File) Name() string { return f.path } const maxConcurrentRequests = 64 // Read reads up to len(b) bytes from the File. It returns the number of // bytes read and an error, if any. EOF is signaled by a zero count with // err set to io.EOF. func (f *File) Read(b []byte) (int, error) { // Split the read into multiple maxPacket sized concurrent reads // bounded by maxConcurrentRequests. This allows reads with a suitably // large buffer to transfer data at a much faster rate due to // overlapping round trip times. inFlight := 0 desiredInFlight := 1 offset := f.offset ch := make(chan result, 1) type inflightRead struct { b []byte offset uint64 } reqs := map[uint32]inflightRead{} type offsetErr struct { offset uint64 err error } var firstErr offsetErr sendReq := func(b []byte, offset uint64) { reqID := f.c.nextID() f.c.dispatchRequest(ch, sshFxpReadPacket{ ID: reqID, Handle: f.handle, Offset: offset, Len: uint32(len(b)), }) inFlight++ reqs[reqID] = inflightRead{b: b, offset: offset} } var read int for len(b) > 0 || inFlight > 0 { for inFlight < desiredInFlight && len(b) > 0 && firstErr.err == nil { l := min(len(b), f.c.maxPacket) rb := b[:l] sendReq(rb, offset) offset += uint64(l) b = b[l:] } if inFlight == 0 { break } select { case res := <-ch: inFlight-- if res.err != nil { firstErr = offsetErr{offset: 0, err: res.err} break } reqID, data := unmarshalUint32(res.data) req, ok := reqs[reqID] if !ok { firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)} break } delete(reqs, reqID) switch res.typ { case ssh_FXP_STATUS: if firstErr.err == nil || req.offset < firstErr.offset { firstErr = offsetErr{ offset: req.offset, err: normaliseError(unmarshalStatus(reqID, res.data)), } break } case ssh_FXP_DATA: l, data := unmarshalUint32(data) n := copy(req.b, data[:l]) read += n if n < len(req.b) { sendReq(req.b[l:], req.offset+uint64(l)) } if desiredInFlight < maxConcurrentRequests { desiredInFlight++ } default: firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)} break } } } // If the error is anything other than EOF, then there // may be gaps in the data copied to the buffer so it's // best to return 0 so the caller can't make any // incorrect assumptions about the state of the buffer. if firstErr.err != nil && firstErr.err != io.EOF { read = 0 } f.offset += uint64(read) return read, firstErr.err } // WriteTo writes the file to w. The return value is the number of bytes // written. Any error encountered during the write is also returned. func (f *File) WriteTo(w io.Writer) (int64, error) { fi, err := f.Stat() if err != nil { return 0, err } inFlight := 0 desiredInFlight := 1 offset := f.offset writeOffset := offset fileSize := uint64(fi.Size()) ch := make(chan result, 1) type inflightRead struct { b []byte offset uint64 } reqs := map[uint32]inflightRead{} pendingWrites := map[uint64][]byte{} type offsetErr struct { offset uint64 err error } var firstErr offsetErr sendReq := func(b []byte, offset uint64) { reqID := f.c.nextID() f.c.dispatchRequest(ch, sshFxpReadPacket{ ID: reqID, Handle: f.handle, Offset: offset, Len: uint32(len(b)), }) inFlight++ reqs[reqID] = inflightRead{b: b, offset: offset} } var copied int64 for firstErr.err == nil || inFlight > 0 { for inFlight < desiredInFlight && firstErr.err == nil { b := make([]byte, f.c.maxPacket) sendReq(b, offset) offset += uint64(f.c.maxPacket) if offset > fileSize { desiredInFlight = 1 } } if inFlight == 0 { break } select { case res := <-ch: inFlight-- if res.err != nil { firstErr = offsetErr{offset: 0, err: res.err} break } reqID, data := unmarshalUint32(res.data) req, ok := reqs[reqID] if !ok { firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)} break } delete(reqs, reqID) switch res.typ { case ssh_FXP_STATUS: if firstErr.err == nil || req.offset < firstErr.offset { firstErr = offsetErr{offset: req.offset, err: normaliseError(unmarshalStatus(reqID, res.data))} break } case ssh_FXP_DATA: l, data := unmarshalUint32(data) if req.offset == writeOffset { nbytes, err := w.Write(data) copied += int64(nbytes) if err != nil { firstErr = offsetErr{offset: req.offset + uint64(nbytes), err: err} break } if nbytes < int(l) { firstErr = offsetErr{offset: req.offset + uint64(nbytes), err: io.ErrShortWrite} break } switch { case offset > fileSize: desiredInFlight = 1 case desiredInFlight < maxConcurrentRequests: desiredInFlight++ } writeOffset += uint64(nbytes) for pendingData, ok := pendingWrites[writeOffset]; ok; pendingData, ok = pendingWrites[writeOffset] { nbytes, err := w.Write(pendingData) if err != nil { firstErr = offsetErr{offset: writeOffset + uint64(nbytes), err: err} break } if nbytes < len(pendingData) { firstErr = offsetErr{offset: writeOffset + uint64(nbytes), err: io.ErrShortWrite} break } writeOffset += uint64(nbytes) inFlight-- } } else { // Don't write the data yet because // this response came in out of order // and we need to wait for responses // for earlier segments of the file. inFlight++ // Pending writes should still be considered inFlight. pendingWrites[req.offset] = data } default: firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)} break } } } if firstErr.err != io.EOF { return copied, firstErr.err } return copied, nil } // Stat returns the FileInfo structure describing file. If there is an // error. func (f *File) Stat() (os.FileInfo, error) { fs, err := f.c.fstat(f.handle) if err != nil { return nil, err } return fileInfoFromStat(fs, path.Base(f.path)), nil } // Write writes len(b) bytes to the File. It returns the number of bytes // written and an error, if any. Write returns a non-nil error when n != // len(b). func (f *File) Write(b []byte) (int, error) { // Split the write into multiple maxPacket sized concurrent writes // bounded by maxConcurrentRequests. This allows writes with a suitably // large buffer to transfer data at a much faster rate due to // overlapping round trip times. inFlight := 0 desiredInFlight := 1 offset := f.offset ch := make(chan result, 1) var firstErr error written := len(b) for len(b) > 0 || inFlight > 0 { for inFlight < desiredInFlight && len(b) > 0 && firstErr == nil { l := min(len(b), f.c.maxPacket) rb := b[:l] f.c.dispatchRequest(ch, sshFxpWritePacket{ ID: f.c.nextID(), Handle: f.handle, Offset: offset, Length: uint32(len(rb)), Data: rb, }) inFlight++ offset += uint64(l) b = b[l:] } if inFlight == 0 { break } select { case res := <-ch: inFlight-- if res.err != nil { firstErr = res.err break } switch res.typ { case ssh_FXP_STATUS: id, _ := unmarshalUint32(res.data) err := normaliseError(unmarshalStatus(id, res.data)) if err != nil && firstErr == nil { firstErr = err break } if desiredInFlight < maxConcurrentRequests { desiredInFlight++ } default: firstErr = unimplementedPacketErr(res.typ) break } } } // If error is non-nil, then there may be gaps in the data written to // the file so it's best to return 0 so the caller can't make any // incorrect assumptions about the state of the file. if firstErr != nil { written = 0 } f.offset += uint64(written) return written, firstErr } // ReadFrom reads data from r until EOF and writes it to the file. The return // value is the number of bytes read. Any error except io.EOF encountered // during the read is also returned. func (f *File) ReadFrom(r io.Reader) (int64, error) { inFlight := 0 desiredInFlight := 1 offset := f.offset ch := make(chan result, 1) var firstErr error read := int64(0) b := make([]byte, f.c.maxPacket) for inFlight > 0 || firstErr == nil { for inFlight < desiredInFlight && firstErr == nil { n, err := r.Read(b) if err != nil { firstErr = err } f.c.dispatchRequest(ch, sshFxpWritePacket{ ID: f.c.nextID(), Handle: f.handle, Offset: offset, Length: uint32(n), Data: b[:n], }) inFlight++ offset += uint64(n) read += int64(n) } if inFlight == 0 { break } select { case res := <-ch: inFlight-- if res.err != nil { firstErr = res.err break } switch res.typ { case ssh_FXP_STATUS: id, _ := unmarshalUint32(res.data) err := normaliseError(unmarshalStatus(id, res.data)) if err != nil && firstErr == nil { firstErr = err break } if desiredInFlight < maxConcurrentRequests { desiredInFlight++ } default: firstErr = unimplementedPacketErr(res.typ) break } } } if firstErr == io.EOF { firstErr = nil } // If error is non-nil, then there may be gaps in the data written to // the file so it's best to return 0 so the caller can't make any // incorrect assumptions about the state of the file. if firstErr != nil { read = 0 } f.offset += uint64(read) return read, firstErr } // Seek implements io.Seeker by setting the client offset for the next Read or // Write. It returns the next offset read. Seeking before or after the end of // the file is undefined. Seeking relative to the end calls Stat. func (f *File) Seek(offset int64, whence int) (int64, error) { switch whence { case os.SEEK_SET: f.offset = uint64(offset) case os.SEEK_CUR: f.offset = uint64(int64(f.offset) + offset) case os.SEEK_END: fi, err := f.Stat() if err != nil { return int64(f.offset), err } f.offset = uint64(fi.Size() + offset) default: return int64(f.offset), unimplementedSeekWhence(whence) } return int64(f.offset), nil } // Chown changes the uid/gid of the current file. func (f *File) Chown(uid, gid int) error { return f.c.Chown(f.path, uid, gid) } // Chmod changes the permissions of the current file. func (f *File) Chmod(mode os.FileMode) error { return f.c.Chmod(f.path, mode) } // Truncate sets the size of the current file. Although it may be safely assumed // that if the size is less than its current size it will be truncated to fit, // the SFTP protocol does not specify what behavior the server should do when setting // size greater than the current size. func (f *File) Truncate(size int64) error { return f.c.Truncate(f.path, size) } func min(a, b int) int { if a > b { return b } return a } // normaliseError normalises an error into a more standard form that can be // checked against stdlib errors like io.EOF or os.ErrNotExist. func normaliseError(err error) error { switch err := err.(type) { case *StatusError: switch err.Code { case ssh_FX_EOF: return io.EOF case ssh_FX_NO_SUCH_FILE: return os.ErrNotExist case ssh_FX_OK: return nil default: return err } default: return err } } func unmarshalStatus(id uint32, data []byte) error { sid, data := unmarshalUint32(data) if sid != id { return &unexpectedIDErr{id, sid} } code, data := unmarshalUint32(data) msg, data, err := unmarshalStringSafe(data) if err != nil { return err } lang, _, _ := unmarshalStringSafe(data) return &StatusError{ Code: code, msg: msg, lang: lang, } } func marshalStatus(b []byte, err StatusError) []byte { b = marshalUint32(b, err.Code) b = marshalString(b, err.msg) b = marshalString(b, err.lang) return b } // flags converts the flags passed to OpenFile into ssh flags. // Unsupported flags are ignored. func flags(f int) uint32 { var out uint32 switch f & os.O_WRONLY { case os.O_WRONLY: out |= ssh_FXF_WRITE case os.O_RDONLY: out |= ssh_FXF_READ } if f&os.O_RDWR == os.O_RDWR { out |= ssh_FXF_READ | ssh_FXF_WRITE } if f&os.O_APPEND == os.O_APPEND { out |= ssh_FXF_APPEND } if f&os.O_CREATE == os.O_CREATE { out |= ssh_FXF_CREAT } if f&os.O_TRUNC == os.O_TRUNC { out |= ssh_FXF_TRUNC } if f&os.O_EXCL == os.O_EXCL { out |= ssh_FXF_EXCL } return out }