github.com/FISCO-BCOS/crypto@v0.0.0-20200202032121-bd8ab0b5d4f1/internal/poll/sendfile_windows.go (about)

     1  // Copyright 2011 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package poll
     6  
     7  import "syscall"
     8  
     9  // SendFile wraps the TransmitFile call.
    10  func SendFile(fd *FD, src syscall.Handle, n int64) (int64, error) {
    11  	if fd.kind == kindPipe {
    12  		// TransmitFile does not work with pipes
    13  		return 0, syscall.ESPIPE
    14  	}
    15  
    16  	if err := fd.writeLock(); err != nil {
    17  		return 0, err
    18  	}
    19  	defer fd.writeUnlock()
    20  
    21  	o := &fd.wop
    22  	o.qty = uint32(n)
    23  	o.handle = src
    24  
    25  	// TODO(brainman): skip calling syscall.Seek if OS allows it
    26  	curpos, err := syscall.Seek(o.handle, 0, 1)
    27  	if err != nil {
    28  		return 0, err
    29  	}
    30  
    31  	o.o.Offset = uint32(curpos)
    32  	o.o.OffsetHigh = uint32(curpos >> 32)
    33  
    34  	done, err := wsrv.ExecIO(o, func(o *operation) error {
    35  		return syscall.TransmitFile(o.fd.Sysfd, o.handle, o.qty, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
    36  	})
    37  	if err == nil {
    38  		// Some versions of Windows (Windows 10 1803) do not set
    39  		// file position after TransmitFile completes.
    40  		// So just use Seek to set file position.
    41  		_, err = syscall.Seek(o.handle, curpos+int64(done), 0)
    42  	}
    43  	return int64(done), err
    44  }