Initial commit: Go 1.23 release state

src/internal/poll/sendfile_bsd.go

@@ -0,0 +1,59 @@
+// 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.
+
+//go:build darwin || dragonfly || freebsd
+
+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, pos, remain int64) (written int64, err error, handled bool) {
+	defer func() {
+		TestHookDidSendFile(dstFD, src, written, err, handled)
+	}()
+	if err := dstFD.writeLock(); err != nil {
+		return 0, err, false
+	}
+	defer dstFD.writeUnlock()
+
+	if err := dstFD.pd.prepareWrite(dstFD.isFile); err != nil {
+		return 0, err, false
+	}
+
+	dst := dstFD.Sysfd
+	for remain > 0 {
+		n := maxSendfileSize
+		if int64(n) > remain {
+			n = int(remain)
+		}
+		pos1 := pos
+		n, err = syscall.Sendfile(dst, src, &pos1, n)
+		if n > 0 {
+			pos += int64(n)
+			written += int64(n)
+			remain -= int64(n)
+		}
+		if err == syscall.EINTR {
+			continue
+		}
+		// This includes syscall.ENOSYS (no kernel
+		// support) and syscall.EINVAL (fd types which
+		// don't implement sendfile), and other errors.
+		// We should end the loop when there is no error
+		// returned from sendfile(2) or it is not a retryable error.
+		if err != syscall.EAGAIN {
+			break
+		}
+		if err = dstFD.pd.waitWrite(dstFD.isFile); err != nil {
+			break
+		}
+	}
+	handled = written != 0 || (err != syscall.ENOSYS && err != syscall.EINVAL)
+	return
+}