1//===-- MmapUtils.h ---------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains compatibility-related preprocessor directives related
10// to mmap.
11//
12//===----------------------------------------------------------------------===//
13
14#ifdef __linux__
15#include <sys/mman.h>
16#include <sys/syscall.h>
17
18// Before kernel 4.17, Linux did not support MAP_FIXED_NOREPLACE, so if it is
19// not available, simplfy define it as MAP_FIXED which performs the same
20// function but does not guarantee existing mappings won't get clobbered.
21#ifndef MAP_FIXED_NOREPLACE
22#define MAP_FIXED_NOREPLACE MAP_FIXED
23#endif
24
25// Some 32-bit architectures don't have mmap and define mmap2 instead. The only
26// difference between the two syscalls is that mmap2's offset parameter is in
27// terms 4096 byte offsets rather than individual bytes, so for our purposes
28// they are effectively the same as all ofsets here are set to 0.
29#if defined(SYS_mmap2) && !defined(SYS_mmap)
30#define SYS_mmap SYS_mmap2
31#endif
32#endif // __linux__
33