118 lines
2.7 KiB
Go
118 lines
2.7 KiB
Go
// 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 (
|
|
"io"
|
|
"os"
|
|
"syscall"
|
|
)
|
|
|
|
// Not strictly needed, but very helpful for debugging, see issue #10221.
|
|
//go:cgo_import_dynamic _ _ "libsendfile.so"
|
|
//go:cgo_import_dynamic _ _ "libsocket.so"
|
|
|
|
// maxSendfileSize is the largest chunk size we ask the kernel to copy
|
|
// at a time.
|
|
const maxSendfileSize int = 4 << 20
|
|
|
|
// 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
|
|
}
|
|
|
|
if err := c.writeLock(); err != nil {
|
|
return 0, err, true
|
|
}
|
|
defer c.writeUnlock()
|
|
|
|
dst := c.sysfd
|
|
src := int(f.Fd())
|
|
for remain > 0 {
|
|
n := maxSendfileSize
|
|
if int64(n) > remain {
|
|
n = int(remain)
|
|
}
|
|
pos1 := pos
|
|
n, err1 := syscall.Sendfile(dst, src, &pos1, n)
|
|
if err1 == syscall.EAGAIN || err1 == syscall.EINTR {
|
|
// partial write may have occurred
|
|
if n = int(pos1 - pos); n == 0 {
|
|
// nothing more to write
|
|
err1 = nil
|
|
}
|
|
}
|
|
if n > 0 {
|
|
pos += int64(n)
|
|
written += int64(n)
|
|
remain -= int64(n)
|
|
}
|
|
if n == 0 && err1 == nil {
|
|
break
|
|
}
|
|
if err1 == syscall.EAGAIN {
|
|
if err1 = c.pd.waitWrite(); err1 == nil {
|
|
continue
|
|
}
|
|
}
|
|
if err1 == syscall.EINTR {
|
|
continue
|
|
}
|
|
if err1 != nil {
|
|
// This includes syscall.ENOSYS (no kernel
|
|
// support) and syscall.EINVAL (fd types which
|
|
// don't implement sendfile)
|
|
err = err1
|
|
break
|
|
}
|
|
}
|
|
if lr != nil {
|
|
lr.N = remain
|
|
}
|
|
if err != nil {
|
|
err = os.NewSyscallError("sendfile", err)
|
|
}
|
|
return written, err, written > 0
|
|
}
|