chromium/third_party/abseil-cpp/absl/base/internal/direct_mmap.h

// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Functions for directly invoking mmap() via syscall, avoiding the case where
// mmap() has been locally overridden.

#ifndef ABSL_BASE_INTERNAL_DIRECT_MMAP_H_
#define ABSL_BASE_INTERNAL_DIRECT_MMAP_H_

#include "absl/base/config.h"

#ifdef ABSL_HAVE_MMAP

#include <sys/mman.h>

#ifdef __linux__

#include <sys/types.h>
#ifdef __BIONIC__
#include <sys/syscall.h>
#else
#include <syscall.h>
#endif

#include <linux/unistd.h>
#include <unistd.h>
#include <cerrno>
#include <cstdarg>
#include <cstdint>

#ifdef __mips__
// Include definitions of the ABI currently in use.
#if defined(__BIONIC__) || !defined(__GLIBC__)
// Android doesn't have sgidefs.h, but does have asm/sgidefs.h, which has the
// definitions we need.
#include <asm/sgidefs.h>
#else
#include <sgidefs.h>
#endif  // __BIONIC__ || !__GLIBC__
#endif  // __mips__

// SYS_mmap and SYS_munmap are not defined in Android.
#ifdef __BIONIC__
extern "C" void* __mmap2(void*, size_t, int, int, int, size_t);
#if defined(__NR_mmap) && !defined(SYS_mmap)
#define SYS_mmap …
#endif
#ifndef SYS_munmap
#define SYS_munmap …
#endif
#endif  // __BIONIC__

#if defined(__NR_mmap2) && !defined(SYS_mmap2)
#define SYS_mmap2 …
#endif

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace base_internal {

// Platform specific logic extracted from
// https://chromium.googlesource.com/linux-syscall-support/+/master/linux_syscall_support.h
inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
                        off_t offset) noexcept { … }

inline int DirectMunmap(void* start, size_t length) { … }

}  // namespace base_internal
ABSL_NAMESPACE_END
}  // namespace absl

#else  // !__linux__

// For non-linux platforms where we have mmap, just dispatch directly to the
// actual mmap()/munmap() methods.

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace base_internal {

inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
                        off_t offset) {
  return mmap(start, length, prot, flags, fd, offset);
}

inline int DirectMunmap(void* start, size_t length) {
  return munmap(start, length);
}

}  // namespace base_internal
ABSL_NAMESPACE_END
}  // namespace absl

#endif  // __linux__

#endif  // ABSL_HAVE_MMAP

#endif  // ABSL_BASE_INTERNAL_DIRECT_MMAP_H_