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package sftp
import (
"bytes"
"encoding/binary"
"io"
"os"
"path"
"sync/atomic"
"syscall"
"time"
"github.com/kr/fs"
"github.com/pkg/errors"
"golang.org/x/crypto/ssh"
)
// InternalInconsistency indicates the packets sent and the data queued to be
// written to the file don't match up. It is an unusual error and usually is
// caused by bad behavior server side or connection issues. The error is
// limited in scope to the call where it happened, the client object is still
// OK to use as long as the connection is still open.
var InternalInconsistency = errors.New("internal inconsistency")
// A ClientOption is a function which applies configuration to a Client.
type ClientOption func(*Client) error
// MaxPacketChecked sets the maximum size of the payload, measured in bytes.
// This option only accepts sizes servers should support, ie. <= 32768 bytes.
//
// If you get the error "failed to send packet header: EOF" when copying a
// large file, try lowering this number.
//
// The default packet size is 32768 bytes.
func MaxPacketChecked(size int) ClientOption {
return func(c *Client) error {
if size < 1 {
return errors.Errorf("size must be greater or equal to 1")
}
if size > 32768 {
return errors.Errorf("sizes larger than 32KB might not work with all servers")
}
c.maxPacket = size
return nil
}
}
// MaxPacketUnchecked sets the maximum size of the payload, measured in bytes.
// It accepts sizes larger than the 32768 bytes all servers should support.
// Only use a setting higher than 32768 if your application always connects to
// the same server or after sufficiently broad testing.
//
// If you get the error "failed to send packet header: EOF" when copying a
// large file, try lowering this number.
//
// The default packet size is 32768 bytes.
func MaxPacketUnchecked(size int) ClientOption {
return func(c *Client) error {
if size < 1 {
return errors.Errorf("size must be greater or equal to 1")
}
c.maxPacket = size
return nil
}
}
// MaxPacket sets the maximum size of the payload, measured in bytes.
// This option only accepts sizes servers should support, ie. <= 32768 bytes.
// This is a synonym for MaxPacketChecked that provides backward compatibility.
//
// If you get the error "failed to send packet header: EOF" when copying a
// large file, try lowering this number.
//
// The default packet size is 32768 bytes.
func MaxPacket(size int) ClientOption {
return MaxPacketChecked(size)
}
// MaxConcurrentRequestsPerFile sets the maximum concurrent requests allowed for a single file.
//
// The default maximum concurrent requests is 64.
func MaxConcurrentRequestsPerFile(n int) ClientOption {
return func(c *Client) error {
if n < 1 {
return errors.Errorf("n must be greater or equal to 1")
}
c.maxConcurrentRequests = n
return nil
}
}
// NewClient creates a new SFTP client on conn, using zero or more option
// functions.
func NewClient(conn *ssh.Client, opts ...ClientOption) (*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 ...ClientOption) (*Client, error) {
sftp := &Client{
clientConn: clientConn{
conn: conn{
Reader: rd,
WriteCloser: wr,
},
inflight: make(map[uint32]chan<- result),
closed: make(chan struct{}),
},
maxPacket: 1 << 15,
maxConcurrentRequests: 64,
}
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
maxConcurrentRequests int
}
// 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. If you need more
// control over the flags/mode used to open the file see client.OpenFile.
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 "", normaliseError(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 "", normaliseError(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, normaliseError(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)
}
}
// RemoveDirectory removes a directory path.
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)
}
}
// PosixRename renames a file using the posix-rename@openssh.com extension
// which will replace newname if it already exists.
func (c *Client) PosixRename(oldname, newname string) error {
id := c.nextID()
typ, data, err := c.sendPacket(sshFxpPosixRenamePacket{
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)
}
}
// MkdirAll creates a directory named path, along with any necessary parents,
// and returns nil, or else returns an error.
// If path is already a directory, MkdirAll does nothing and returns nil.
// If path contains a regular file, an error is returned
func (c *Client) MkdirAll(path string) error {
// Most of this code mimics https://golang.org/src/os/path.go?s=514:561#L13
// Fast path: if we can tell whether path is a directory or file, stop with success or error.
dir, err := c.Stat(path)
if err == nil {
if dir.IsDir() {
return nil
}
return &os.PathError{Op: "mkdir", Path: path, Err: syscall.ENOTDIR}
}
// Slow path: make sure parent exists and then call Mkdir for path.
i := len(path)
for i > 0 && os.IsPathSeparator(path[i-1]) { // Skip trailing path separator.
i--
}
j := i
for j > 0 && !os.IsPathSeparator(path[j-1]) { // Scan backward over element.
j--
}
if j > 1 {
// Create parent
err = c.MkdirAll(path[0 : j-1])
if err != nil {
return err
}
}
// Parent now exists; invoke Mkdir and use its result.
err = c.Mkdir(path)
if err != nil {
// Handle arguments like "foo/." by
// double-checking that directory doesn't exist.
dir, err1 := c.Lstat(path)
if err1 == nil && dir.IsDir() {
return nil
}
return err
}
return nil
}
// applyOptions applies options functions to the Client.
// If an error is encountered, option processing ceases.
func (c *Client) applyOptions(opts ...ClientOption) 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
}
// Read reads up to len(b) bytes from the File. It returns the number of bytes
// read and an error, if any. Read follows io.Reader semantics, so when Read
// encounters an error or EOF condition after successfully reading n > 0 bytes,
// it returns the number of bytes read.
//
// To maximise throughput for transferring the entire file (especially
// over high latency links) it is recommended to use WriteTo rather
// than calling Read multiple times. io.Copy will do this
// automatically.
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
// maxConcurrentRequests buffer to deal with broadcastErr() floods
// also must have a buffer of max value of (desiredInFlight - inFlight)
ch := make(chan result, f.c.maxConcurrentRequests+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
}
res := <-ch
inFlight--
if res.err != nil {
firstErr = offsetErr{offset: 0, err: res.err}
continue
}
reqID, data := unmarshalUint32(res.data)
req, ok := reqs[reqID]
if !ok {
firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)}
continue
}
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)),
}
}
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 < f.c.maxConcurrentRequests {
desiredInFlight++
}
default:
firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)}
}
}
// 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.
//
// This method is preferred over calling Read multiple times to
// maximise throughput for transferring the entire file (especially
// over high latency links).
func (f *File) WriteTo(w io.Writer) (int64, error) {
fi, err := f.c.Stat(f.path)
if err != nil {
return 0, err
}
inFlight := 0
desiredInFlight := 1
offset := f.offset
writeOffset := offset
fileSize := uint64(fi.Size())
// see comment on same line in Read() above
ch := make(chan result, f.c.maxConcurrentRequests+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 {
if firstErr.err == nil {
for inFlight+len(pendingWrites) < desiredInFlight {
b := make([]byte, f.c.maxPacket)
sendReq(b, offset)
offset += uint64(f.c.maxPacket)
if offset > fileSize {
desiredInFlight = 1
}
}
}
if inFlight == 0 {
if firstErr.err == nil && len(pendingWrites) > 0 {
return copied, InternalInconsistency
}
break
}
res := <-ch
inFlight--
if res.err != nil {
firstErr = offsetErr{offset: 0, err: res.err}
continue
}
reqID, data := unmarshalUint32(res.data)
req, ok := reqs[reqID]
if !ok {
firstErr = offsetErr{offset: 0, err: errors.Errorf("sid: %v not found", reqID)}
continue
}
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))}
}
case ssh_FXP_DATA:
l, data := unmarshalUint32(data)
if req.offset == writeOffset {
nbytes, err := w.Write(data)
copied += int64(nbytes)
if err != nil {
// We will never receive another DATA with offset==writeOffset, so
// the loop will drain inFlight and then exit.
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 < f.c.maxConcurrentRequests:
desiredInFlight++
}
writeOffset += uint64(nbytes)
for {
pendingData, ok := pendingWrites[writeOffset]
if !ok {
break
}
// Give go a chance to free the memory.
delete(pendingWrites, writeOffset)
nbytes, err := w.Write(pendingData)
// Do not move writeOffset on error so subsequent iterations won't trigger
// any writes.
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)
}
} 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.
pendingWrites[req.offset] = data
}
default:
firstErr = offsetErr{offset: 0, err: unimplementedPacketErr(res.typ)}
}
}
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).
//
// To maximise throughput for transferring the entire file (especially
// over high latency links) it is recommended to use ReadFrom rather
// than calling Write multiple times. io.Copy will do this
// automatically.
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
// see comment on same line in Read() above
ch := make(chan result, f.c.maxConcurrentRequests+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
}
res := <-ch
inFlight--
if res.err != nil {
firstErr = res.err
continue
}
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 < f.c.maxConcurrentRequests {
desiredInFlight++
}
default:
firstErr = unimplementedPacketErr(res.typ)
}
}
// 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.
//
// This method is preferred over calling Write multiple times to
// maximise throughput for transferring the entire file (especially
// over high latency links).
func (f *File) ReadFrom(r io.Reader) (int64, error) {
inFlight := 0
desiredInFlight := 1
offset := f.offset
// see comment on same line in Read() above
ch := make(chan result, f.c.maxConcurrentRequests+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
}
res := <-ch
inFlight--
if res.err != nil {
firstErr = res.err
continue
}
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 < f.c.maxConcurrentRequests {
desiredInFlight++
}
default:
firstErr = unimplementedPacketErr(res.typ)
}
}
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 io.SeekStart:
f.offset = uint64(offset)
case io.SeekCurrent:
f.offset = uint64(int64(f.offset) + offset)
case io.SeekEnd:
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, _ := unmarshalStringSafe(data)
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
}
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