github.com/s1s1ty/go@v0.0.0-20180207192209-104445e3140f/src/net/sendfile_solaris.go (about)

     1  // Copyright 2015 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  )
    12  
    13  // sendFile copies the contents of r to c using the sendfile
    14  // system call to minimize copies.
    15  //
    16  // if handled == true, sendFile returns the number of bytes copied and any
    17  // non-EOF error.
    18  //
    19  // if handled == false, sendFile performed no work.
    20  func sendFile(c *netFD, r io.Reader) (written int64, err error, handled bool) {
    21  	// Solaris uses 0 as the "until EOF" value. If you pass in more bytes than the
    22  	// file contains, it will loop back to the beginning ad nauseam until it's sent
    23  	// exactly the number of bytes told to. As such, we need to know exactly how many
    24  	// bytes to send.
    25  	var remain int64 = 0
    26  
    27  	lr, ok := r.(*io.LimitedReader)
    28  	if ok {
    29  		remain, r = lr.N, lr.R
    30  		if remain <= 0 {
    31  			return 0, nil, true
    32  		}
    33  	}
    34  	f, ok := r.(*os.File)
    35  	if !ok {
    36  		return 0, nil, false
    37  	}
    38  
    39  	if remain == 0 {
    40  		fi, err := f.Stat()
    41  		if err != nil {
    42  			return 0, err, false
    43  		}
    44  
    45  		remain = fi.Size()
    46  	}
    47  
    48  	// The other quirk with Solaris's sendfile implementation is that it doesn't
    49  	// use the current position of the file -- if you pass it offset 0, it starts
    50  	// from offset 0. There's no way to tell it "start from current position", so
    51  	// we have to manage that explicitly.
    52  	pos, err := f.Seek(0, io.SeekCurrent)
    53  	if err != nil {
    54  		return 0, err, false
    55  	}
    56  
    57  	written, err = poll.SendFile(&c.pfd, int(f.Fd()), pos, remain)
    58  
    59  	if lr != nil {
    60  		lr.N = remain - written
    61  	}
    62  	return written, wrapSyscallError("sendfile", err), written > 0
    63  }