// sendFile copies the contents of r to c using the TransmitFile
// 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.
//
// Note that sendfile for windows does not suppport >2GB file.
func sendFile(fd *netFD, r io.Reader) (written int64, err error, handled bool) {
var n int64 = 0 // by default, copy until EOF
lr, ok := r.(*io.LimitedReader)
if ok {
n, r = lr.N, lr.R
if n <= 0 {
return 0, nil, true
}
}
f, ok := r.(*os.File)
if !ok {
return 0, nil, false
}
if err := fd.writeLock(); err != nil {
return 0, err, true
}
defer fd.writeUnlock()
o := &fd.wop
o.qty = uint32(n)
o.handle = syscall.Handle(f.Fd())
done, err := wsrv.ExecIO(o, "TransmitFile", func(o *operation) error {
return syscall.TransmitFile(o.fd.sysfd, o.handle, o.qty, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
})
if err != nil {
return 0, err, false
}
if lr != nil {
lr.N -= int64(done)
}
return int64(done), nil, true
}
func (o *sendfileOp) Submit() (errno int) {
return syscall.TransmitFile(o.fd.sysfd, o.src, o.n, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
}