1 files changed, 55 insertions, 0 deletions
diff --git a/src/internal/poll/sendfile_linux.go b/src/internal/poll/sendfile_linux.go
new file mode 100644
index 0000000..d6442e8
--- /dev/null
+++ b/src/internal/poll/sendfile_linux.go
@@ -0,0 +1,55 @@
+// 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 "syscall"
+
+// 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, 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 := int(dstFD.Sysfd)
+	var written int64
+	var err error
+	for remain > 0 {
+		n := maxSendfileSize
+		if int64(n) > remain {
+			n = int(remain)
+		}
+		n, err1 := syscall.Sendfile(dst, src, nil, n)
+		if n > 0 {
+			written += int64(n)
+			remain -= int64(n)
+		} else if n == 0 && err1 == nil {
+			break
+		}
+		if err1 == syscall.EINTR {
+			continue
+		}
+		if err1 == syscall.EAGAIN {
+			if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil {
+				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
+}