1 files changed, 22 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/base/mapfile_read.go b/src/cmd/compile/internal/base/mapfile_read.go
new file mode 100644
index 0000000000..01796a9bab
--- /dev/null
+++ b/src/cmd/compile/internal/base/mapfile_read.go
@@ -0,0 +1,22 @@
+// Copyright 2018 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 && !linux && !netbsd && !openbsd
+// +build !darwin,!dragonfly,!freebsd,!linux,!netbsd,!openbsd
+
+package base
+
+import (
+	"io"
+	"os"
+)
+
+func MapFile(f *os.File, offset, length int64) (string, error) {
+	buf := make([]byte, length)
+	_, err := io.ReadFull(io.NewSectionReader(f, offset, length), buf)
+	if err != nil {
+		return "", err
+	}
+	return string(buf), nil
+}