protected_pages.h | Explore in Territory

//===-- protected_pages.h -------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// This file provides protected pages that fault when accessing prior or past
// it. This is useful to check memory functions that must not access outside of
// the provided size limited buffer.
//===----------------------------------------------------------------------===//

#ifndef LIBC_TEST_SRC_STRING_MEMORY_UTILS_PROTECTED_PAGES_H
#define LIBC_TEST_SRC_STRING_MEMORY_UTILS_PROTECTED_PAGES_H

#include "src/__support/macros/properties/os.h" // LIBC_TARGET_OS_IS_LINUX
#if defined(LIBC_FULL_BUILD) || !defined(LIBC_TARGET_OS_IS_LINUX)
#error "Protected pages requires mmap and cannot be used in full build mode."
#endif // defined(LIBC_FULL_BUILD) || !defined(LIBC_TARGET_OS_IS_LINUX)

#include "src/__support/macros/attributes.h" // LIBC_INLINE
#include <stddef.h>                          // size_t
#include <stdint.h>                          // uint8_t
#include <sys/mman.h>                        // mmap, munmap
#include <unistd.h>                          // sysconf, _SC_PAGESIZE

// Returns mmap page size.
LIBC_INLINE size_t GetPageSize() { … }

// Represents a page of memory whose access can be configured throught the
// 'WithAccess' function. Accessing data above or below this page will trap as
// it is sandwiched between two pages with no read / write access.
struct Page { … };

// Allocates 5 consecutive pages that will trap if accessed.
// | page layout | access | page name |
// |-------------|--------|:---------:|
// | 0           | trap   |           |
// | 1           | custom |     A     |
// | 2           | trap   |           |
// | 3           | custom |     B     |
// | 4           | trap   |           |
//
// The pages A and B can be retrieved as with 'GetPageA' / 'GetPageB' and their
// accesses can be customized through the 'WithAccess' function.
struct ProtectedPages { … };

#endif // LIBC_TEST_SRC_STRING_MEMORY_UTILS_PROTECTED_PAGES_H
llvm/libc/test/src/string/memory_utils/protected_pages.h
