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Source file src/net/sendfile_solaris.go

Documentation: net

  // Copyright 2015 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  package net
  
  import (
  	"internal/poll"
  	"io"
  	"os"
  )
  
  // sendFile copies the contents of r to c using the sendfile
  // system call to minimize copies.
  //
  // if handled == true, sendFile returns the number of bytes copied and any
  // non-EOF error.
  //
  // if handled == false, sendFile performed no work.
  func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
  	// Solaris uses 0 as the "until EOF" value. If you pass in more bytes than the
  	// file contains, it will loop back to the beginning ad nauseam until it's sent
  	// exactly the number of bytes told to. As such, we need to know exactly how many
  	// bytes to send.
  	var remain int64 = 0
  
  	lr, ok := r.(*io.LimitedReader)
  	if ok {
  		remain, r = lr.N, lr.R
  		if remain <= 0 {
  			return 0, nil, true
  		}
  	}
  	f, ok := r.(*os.File)
  	if !ok {
  		return 0, nil, false
  	}
  
  	if remain == 0 {
  		fi, err := f.Stat()
  		if err != nil {
  			return 0, err, false
  		}
  
  		remain = fi.Size()
  	}
  
  	// The other quirk with Solaris's sendfile implementation is that it doesn't
  	// use the current position of the file -- if you pass it offset 0, it starts
  	// from offset 0. There's no way to tell it "start from current position", so
  	// we have to manage that explicitly.
  	pos, err := f.Seek(0, io.SeekCurrent)
  	if err != nil {
  		return 0, err, false
  	}
  
  	written, err = poll.SendFile(&c.pfd, int(f.Fd()), pos, remain)
  
  	if lr != nil {
  		lr.N = remain - written
  	}
  	return written, wrapSyscallError("sendfile", err), written > 0
  }
  

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