You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: sendfile_solaris.go
    path of file: ./repos/gccrs/libgo/go/internal/poll
    
    the code of the file until where you have to start completion: // 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 poll

import "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 wraps the sendfile system call.
func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
	if err := dstFD.writeLock(); err != nil {
		return 0, err
	}
	defer dstFD.writeUnlock()
	if err := ds
    
func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
	if err := dstFD.writeLock(); err != nil {
		return 0, err
	}
	defer dstFD.writeUnlock()
	if err := dstFD.pd.prepareWrite(dstFD.isFile); err != nil {
		return 0, err
	}

	dst := dstFD.Sysfd
	var written int64
	var err error
	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
			n = int(pos1 - pos)
		}
		if n > 0 {
			pos += int64(n)
			written += int64(n)
			remain -= int64(n)
		} else if n == 0 && err1 == nil {
			break
		}
		if err1 == syscall.EAGAIN {
			if err1 = dstFD.pd.waitWrite(dstFD.isFile); 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
		}
	}
	return written, err
}