// Copyright 2011 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 (
"io"
"syscall"
)
// SendFile wraps the TransmitFile call.
func SendFile(fd *FD, src uintptr, size int64) (written int64, err error, handled bool) {
defer func() {
TestHookDidSendFile(fd, 0, written, err, written > 0)
}()
if fd.kind == kindPipe {
// TransmitFile does not work with pipes
return 0, syscall.ESPIPE, false
}
hsrc := syscall.Handle(src)
if ft, _ := syscall.GetFileType(hsrc); ft == syscall.FILE_TYPE_PIPE {
return 0, syscall.ESPIPE, false
}
if err := fd.writeLock(); err != nil {
return 0, err, false
}
defer fd.writeUnlock()
// Get the file size so we don't read past the end of the file.
var fi syscall.ByHandleFileInformation
if err := syscall.GetFileInformationByHandle(hsrc, &fi); err != nil {
return 0, err, false
}
fileSize := int64(fi.FileSizeHigh)<<32 + int64(fi.FileSizeLow)
startpos, err := syscall.Seek(hsrc, 0, io.SeekCurrent)
if err != nil {
return 0, err, false
}
maxSize := fileSize - startpos
if size <= 0 {
size = maxSize
} else {
size = min(size, maxSize)
}
defer func() {
if written > 0 {
// Some versions of Windows (Windows 10 1803) do not set
// file position after TransmitFile completes.
// So just use Seek to set file position.
_, serr := syscall.Seek(hsrc, startpos+written, io.SeekStart)
if err != nil {
err = serr
}
}
}()
// TransmitFile can be invoked in one call with at most
// 2,147,483,646 bytes: the maximum value for a 32-bit integer minus 1.
// See https://docs.microsoft.com/en-us/windows/win32/api/mswsock/nf-mswsock-transmitfile
const maxChunkSizePerCall = int64(0x7fffffff - 1)
o := &fd.wop
o.handle = hsrc
for size > 0 {
chunkSize := maxChunkSizePerCall
if chunkSize > size {
chunkSize = size
}
off := startpos + written
o.o.Offset = uint32(off)
o.o.OffsetHigh = uint32(off >> 32)
n, err := execIO(o, func(o *operation) error {
o.qty = uint32(chunkSize)
return syscall.TransmitFile(o.fd.Sysfd, o.handle, o.qty, 0, &o.o, nil, syscall.TF_WRITE_BEHIND)
})
if err != nil {
return written, err, written > 0
}
size -= int64(n)
written += int64(n)
}
return written, nil, written > 0
}
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