1 files changed, 36 insertions, 0 deletions
diff --git a/src/cmd/go/internal/mmap/mmap_unix.go b/src/cmd/go/internal/mmap/mmap_unix.go
new file mode 100644
index 0000000..53bcbb9
--- /dev/null
+++ b/src/cmd/go/internal/mmap/mmap_unix.go
@@ -0,0 +1,36 @@
+// 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 unix
+
+package mmap
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"syscall"
+)
+
+func mmapFile(f *os.File) (Data, error) {
+	st, err := f.Stat()
+	if err != nil {
+		return Data{}, err
+	}
+	size := st.Size()
+	pagesize := int64(os.Getpagesize())
+	if int64(int(size+(pagesize-1))) != size+(pagesize-1) {
+		return Data{}, fmt.Errorf("%s: too large for mmap", f.Name())
+	}
+	n := int(size)
+	if n == 0 {
+		return Data{f, nil}, nil
+	}
+	mmapLength := int(((size + pagesize - 1) / pagesize) * pagesize) // round up to page size
+	data, err := syscall.Mmap(int(f.Fd()), 0, mmapLength, syscall.PROT_READ, syscall.MAP_SHARED)
+	if err != nil {
+		return Data{}, &fs.PathError{Op: "mmap", Path: f.Name(), Err: err}
+	}
+	return Data{f, data[:n]}, nil
+}