github.com/tidwall/go@v0.0.0-20170415222209-6694a6888b7d/src/net/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 net
     6  
     7  import (
     8  	"internal/poll"
     9  	"io"
    10  	"os"
    11  	"syscall"
    12  )
    13  
    14  // sendFile copies the contents of r to c using the TransmitFile
    15  // system call to minimize copies.
    16  //
    17  // if handled == true, sendFile returns the number of bytes copied and any
    18  // non-EOF error.
    19  //
    20  // if handled == false, sendFile performed no work.
    21  //
    22  // Note that sendfile for windows does not support >2GB file.
    23  func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
    24  	var n int64 = 0 // by default, copy until EOF
    25  
    26  	lr, ok := r.(*io.LimitedReader)
    27  	if ok {
    28  		n, r = lr.N, lr.R
    29  		if n <= 0 {
    30  			return 0, nil, true
    31  		}
    32  	}
    33  	f, ok := r.(*os.File)
    34  	if !ok {
    35  		return 0, nil, false
    36  	}
    37  
    38  	done, err := poll.SendFile(&fd.pfd, syscall.Handle(f.Fd()), n)
    39  
    40  	if err != nil {
    41  		return 0, wrapSyscallError("transmitfile", err), false
    42  	}
    43  	if lr != nil {
    44  		lr.N -= int64(done)
    45  	}
    46  	return int64(done), nil, true
    47  }