Function read_

lib/protocol/SFTP.js:2101–2183

(self, handle, buf, off, len, position, cb, req_)

}

function read_(self, handle, buf, off, len, position, cb, req_) {
  const maxDataLen = self._maxReadLen;
  const overflow = Math.max(len - maxDataLen, 0);

  if (overflow)
    len = maxDataLen;

  /*
    uint32     id
    string     handle
    uint64     offset
    uint32     len
  */
  const handleLen = handle.length;
  let p = 9;
  let pos = position;
  const out = Buffer.allocUnsafe(4 + 1 + 4 + 4 + handleLen + 8 + 4);

  writeUInt32BE(out, out.length - 4, 0);
  out[4] = REQUEST.READ;
  const reqid = self._writeReqid = (self._writeReqid + 1) & MAX_REQID;
  writeUInt32BE(out, reqid, 5);

  writeUInt32BE(out, handleLen, p);
  out.set(handle, p += 4);
  p += handleLen;
  for (let i = 7; i >= 0; --i) {
    out[p + i] = pos & 0xFF;
    pos /= 256;
  }
  writeUInt32BE(out, len, p += 8);

  if (typeof cb !== 'function')
    cb = noop;

  const req = (req_ || {
    nb: 0,
    position,
    off,
    origOff: off,
    len: undefined,
    overflow: undefined,
    cb: (err, data, nb) => {
      const len = req.len;
      const overflow = req.overflow;

      if (err) {
        if (cb._wantEOFError || err.code !== STATUS_CODE.EOF)
          return cb(err);
      } else if (nb > len) {
        return cb(new Error('Received more data than requested'));
      } else if (nb === len && overflow) {
        req.nb += nb;
        req.position += nb;
        req.off += nb;
        read_(self, handle, buf, req.off, overflow, req.position, cb, req);
        return;
      }