mirror of
https://github.com/restic/restic.git
synced 2024-09-07 11:59:25 +02:00
232 lines
5.4 KiB
Go
232 lines
5.4 KiB
Go
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package sftp
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import (
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"encoding"
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"io"
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"os"
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"path/filepath"
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"strconv"
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"sync"
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"syscall"
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"github.com/pkg/errors"
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)
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var maxTxPacket uint32 = 1 << 15
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type handleHandler func(string) string
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// Handlers contains the 4 SFTP server request handlers.
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type Handlers struct {
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FileGet FileReader
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FilePut FileWriter
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FileCmd FileCmder
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FileInfo FileInfoer
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}
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// RequestServer abstracts the sftp protocol with an http request-like protocol
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type RequestServer struct {
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*serverConn
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Handlers Handlers
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pktMgr packetManager
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openRequests map[string]Request
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openRequestLock sync.RWMutex
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handleCount int
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}
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// NewRequestServer creates/allocates/returns new RequestServer.
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// Normally there there will be one server per user-session.
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func NewRequestServer(rwc io.ReadWriteCloser, h Handlers) *RequestServer {
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svrConn := &serverConn{
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conn: conn{
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Reader: rwc,
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WriteCloser: rwc,
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},
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}
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return &RequestServer{
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serverConn: svrConn,
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Handlers: h,
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pktMgr: newPktMgr(svrConn),
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openRequests: make(map[string]Request),
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}
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}
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func (rs *RequestServer) nextRequest(r Request) string {
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rs.openRequestLock.Lock()
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defer rs.openRequestLock.Unlock()
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rs.handleCount++
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handle := strconv.Itoa(rs.handleCount)
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rs.openRequests[handle] = r
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return handle
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}
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func (rs *RequestServer) getRequest(handle string) (Request, bool) {
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rs.openRequestLock.RLock()
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defer rs.openRequestLock.RUnlock()
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r, ok := rs.openRequests[handle]
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return r, ok
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}
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func (rs *RequestServer) closeRequest(handle string) {
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rs.openRequestLock.Lock()
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defer rs.openRequestLock.Unlock()
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if r, ok := rs.openRequests[handle]; ok {
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r.close()
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delete(rs.openRequests, handle)
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}
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}
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// Close the read/write/closer to trigger exiting the main server loop
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func (rs *RequestServer) Close() error { return rs.conn.Close() }
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// Serve requests for user session
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func (rs *RequestServer) Serve() error {
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var wg sync.WaitGroup
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runWorker := func(ch requestChan) {
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wg.Add(1)
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go func() {
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defer wg.Done()
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if err := rs.packetWorker(ch); err != nil {
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rs.conn.Close() // shuts down recvPacket
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}
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}()
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}
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pktChan := rs.pktMgr.workerChan(runWorker)
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var err error
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var pkt requestPacket
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var pktType uint8
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var pktBytes []byte
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for {
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pktType, pktBytes, err = rs.recvPacket()
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if err != nil {
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break
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}
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pkt, err = makePacket(rxPacket{fxp(pktType), pktBytes})
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if err != nil {
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debug("makePacket err: %v", err)
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rs.conn.Close() // shuts down recvPacket
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break
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}
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pktChan <- pkt
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}
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close(pktChan) // shuts down sftpServerWorkers
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wg.Wait() // wait for all workers to exit
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return err
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}
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func (rs *RequestServer) packetWorker(pktChan chan requestPacket) error {
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for pkt := range pktChan {
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var rpkt responsePacket
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switch pkt := pkt.(type) {
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case *sshFxInitPacket:
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rpkt = sshFxVersionPacket{sftpProtocolVersion, nil}
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case *sshFxpClosePacket:
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handle := pkt.getHandle()
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rs.closeRequest(handle)
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rpkt = statusFromError(pkt, nil)
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case *sshFxpRealpathPacket:
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rpkt = cleanPath(pkt)
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case isOpener:
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handle := rs.nextRequest(requestFromPacket(pkt))
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rpkt = sshFxpHandlePacket{pkt.id(), handle}
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case *sshFxpFstatPacket:
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handle := pkt.getHandle()
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request, ok := rs.getRequest(handle)
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if !ok {
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rpkt = statusFromError(pkt, syscall.EBADF)
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} else {
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request = requestFromPacket(
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&sshFxpStatPacket{ID: pkt.id(), Path: request.Filepath})
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rpkt = rs.handle(request, pkt)
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}
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case *sshFxpFsetstatPacket:
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handle := pkt.getHandle()
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request, ok := rs.getRequest(handle)
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if !ok {
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rpkt = statusFromError(pkt, syscall.EBADF)
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} else {
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request = requestFromPacket(
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&sshFxpSetstatPacket{ID: pkt.id(), Path: request.Filepath,
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Flags: pkt.Flags, Attrs: pkt.Attrs,
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})
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rpkt = rs.handle(request, pkt)
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}
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case hasHandle:
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handle := pkt.getHandle()
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request, ok := rs.getRequest(handle)
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request.update(pkt)
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if !ok {
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rpkt = statusFromError(pkt, syscall.EBADF)
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} else {
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rpkt = rs.handle(request, pkt)
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}
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case hasPath:
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request := requestFromPacket(pkt)
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rpkt = rs.handle(request, pkt)
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default:
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return errors.Errorf("unexpected packet type %T", pkt)
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}
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err := rs.sendPacket(rpkt)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func cleanPath(pkt *sshFxpRealpathPacket) responsePacket {
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path := pkt.getPath()
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if !filepath.IsAbs(path) {
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path = "/" + path
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} // all paths are absolute
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cleaned_path := filepath.Clean(path)
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return &sshFxpNamePacket{
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ID: pkt.id(),
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NameAttrs: []sshFxpNameAttr{{
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Name: cleaned_path,
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LongName: cleaned_path,
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Attrs: emptyFileStat,
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}},
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}
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}
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func (rs *RequestServer) handle(request Request, pkt requestPacket) responsePacket {
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// fmt.Println("Request Method: ", request.Method)
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rpkt, err := request.handle(rs.Handlers)
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if err != nil {
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err = errorAdapter(err)
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rpkt = statusFromError(pkt, err)
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}
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return rpkt
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}
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// Wrap underlying connection methods to use packetManager
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func (rs *RequestServer) sendPacket(m encoding.BinaryMarshaler) error {
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if pkt, ok := m.(responsePacket); ok {
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rs.pktMgr.readyPacket(pkt)
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} else {
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return errors.Errorf("unexpected packet type %T", m)
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}
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return nil
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}
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func (rs *RequestServer) sendError(p ider, err error) error {
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return rs.sendPacket(statusFromError(p, err))
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}
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// os.ErrNotExist should convert to ssh_FX_NO_SUCH_FILE, but is not recognized
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// by statusFromError. So we convert to syscall.ENOENT which it does.
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func errorAdapter(err error) error {
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if err == os.ErrNotExist {
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return syscall.ENOENT
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}
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return err
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}
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