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-rw-r--r--src/internal/poll/sendfile_windows.go81
1 files changed, 81 insertions, 0 deletions
diff --git a/src/internal/poll/sendfile_windows.go b/src/internal/poll/sendfile_windows.go
new file mode 100644
index 0000000..50c3ee8
--- /dev/null
+++ b/src/internal/poll/sendfile_windows.go
@@ -0,0 +1,81 @@
+// 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 syscall.Handle, n int64) (written int64, err error) {
+ if fd.kind == kindPipe {
+ // TransmitFile does not work with pipes
+ return 0, syscall.ESPIPE
+ }
+
+ if err := fd.writeLock(); err != nil {
+ return 0, err
+ }
+ defer fd.writeUnlock()
+
+ o := &fd.wop
+ o.handle = src
+
+ // TODO(brainman): skip calling syscall.Seek if OS allows it
+ curpos, err := syscall.Seek(o.handle, 0, io.SeekCurrent)
+ if err != nil {
+ return 0, err
+ }
+
+ if n <= 0 { // We don't know the size of the file so infer it.
+ // Find the number of bytes offset from curpos until the end of the file.
+ n, err = syscall.Seek(o.handle, -curpos, io.SeekEnd)
+ if err != nil {
+ return
+ }
+ // Now seek back to the original position.
+ if _, err = syscall.Seek(o.handle, curpos, io.SeekStart); err != nil {
+ return
+ }
+ }
+
+ // 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)
+
+ for n > 0 {
+ chunkSize := maxChunkSizePerCall
+ if chunkSize > n {
+ chunkSize = n
+ }
+
+ o.qty = uint32(chunkSize)
+ o.o.Offset = uint32(curpos)
+ o.o.OffsetHigh = uint32(curpos >> 32)
+
+ nw, err := execIO(o, 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 written, err
+ }
+
+ curpos += int64(nw)
+
+ // Some versions of Windows (Windows 10 1803) do not set
+ // file position after TransmitFile completes.
+ // So just use Seek to set file position.
+ if _, err = syscall.Seek(o.handle, curpos, io.SeekStart); err != nil {
+ return written, err
+ }
+
+ n -= int64(nw)
+ written += int64(nw)
+ }
+
+ return
+}