51 lines
1.0 KiB
Go
51 lines
1.0 KiB
Go
//go:build darwin || dragonfly || freebsd || linux || nacl || netbsd || openbsd
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// +build darwin dragonfly freebsd linux nacl netbsd openbsd
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package mmap provides a way to memory-map a file.
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package mmap
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import (
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"os"
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"syscall"
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)
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// Map memory-maps a file.
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func Map(path string, sz int64) ([]byte, error) {
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f, err := os.Open(path)
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if err != nil {
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return nil, err
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}
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defer f.Close()
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fi, err := f.Stat()
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if err != nil {
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return nil, err
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} else if fi.Size() == 0 {
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return nil, nil
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}
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// Use file size if map size is not passed in.
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if sz == 0 {
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sz = fi.Size()
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}
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data, err := syscall.Mmap(int(f.Fd()), 0, int(sz), syscall.PROT_READ, syscall.MAP_SHARED)
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if err != nil {
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return nil, err
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}
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return data, nil
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}
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// Unmap closes the memory-map.
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func Unmap(data []byte) error {
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if data == nil {
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return nil
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}
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return syscall.Munmap(data)
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}
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