unix/mmap_unix_test.go

// Copyright 2014 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 aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris

package unix_test

import (
	"runtime"
	"testing"

	"golang.org/x/sys/unix"
)

func TestMmap(t *testing.T) {
	mmapProt := unix.PROT_NONE
	mprotectProt := unix.PROT_READ | unix.PROT_WRITE
	// On NetBSD PAX mprotect prohibits setting protection bits
	// missing from the original mmap call unless explicitly
	// requested with PROT_MPROTECT.
	if runtime.GOOS == "netbsd" {
		// PROT_MPROTECT(x) is defined as ((x) << 3):
		// https://github.com/NetBSD/src/blob/aba449a55bf91b44bc68f542edd9afa341962b89/sys/sys/mman.h#L73
		mmapProt = mprotectProt << 3
	}
	b, err := unix.Mmap(-1, 0, unix.Getpagesize(), mmapProt, unix.MAP_ANON|unix.MAP_PRIVATE)
	if err != nil {
		t.Fatalf("Mmap: %v", err)
	}
	if err := unix.Mprotect(b, mprotectProt); err != nil {
		t.Fatalf("Mprotect: %v", err)
	}

	b[0] = 42

	if runtime.GOOS == "aix" {
		t.Skip("msync returns invalid argument for AIX, skipping msync test")
	} else {
		if err := unix.Msync(b, unix.MS_SYNC); err != nil {
			t.Fatalf("Msync: %v", err)
		}
	}

	if err := unix.Madvise(b, unix.MADV_DONTNEED); err != nil {
		t.Fatalf("Madvise: %v", err)
	}
	if err := unix.Munmap(b); err != nil {
		t.Fatalf("Munmap: %v", err)
	}
}