1  //===-- sanitizer_getauxval.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  // Common getauxval() guards and definitions.
      10  // getauxval() is not defined until glibc version 2.16, or until API level 21
      11  // for Android.
      12  // Implement the getauxval() compat function for NetBSD.
      13  //
      14  //===----------------------------------------------------------------------===//
      15  
      16  #ifndef SANITIZER_GETAUXVAL_H
      17  #define SANITIZER_GETAUXVAL_H
      18  
      19  #include "sanitizer_platform.h"
      20  #include "sanitizer_glibc_version.h"
      21  
      22  #if SANITIZER_LINUX || SANITIZER_FUCHSIA
      23  
      24  # if (__GLIBC_PREREQ(2, 16) || (SANITIZER_ANDROID && __ANDROID_API__ >= 21) || \
      25        SANITIZER_FUCHSIA) &&                                                    \
      26       !SANITIZER_GO
      27  #  define SANITIZER_USE_GETAUXVAL 1
      28  # else
      29  #  define SANITIZER_USE_GETAUXVAL 0
      30  # endif
      31  
      32  # if SANITIZER_USE_GETAUXVAL
      33  #  include <sys/auxv.h>
      34  # else
      35  // The weak getauxval definition allows to check for the function at runtime.
      36  // This is useful for Android, when compiled at a lower API level yet running
      37  // on a more recent platform that offers the function.
      38  extern "C" SANITIZER_WEAK_ATTRIBUTE unsigned long getauxval(unsigned long type);
      39  # endif
      40  
      41  #elif SANITIZER_NETBSD
      42  
      43  #define SANITIZER_USE_GETAUXVAL 1
      44  
      45  #include <dlfcn.h>
      46  #include <elf.h>
      47  
      48  static inline decltype(AuxInfo::a_v) getauxval(decltype(AuxInfo::a_type) type) {
      49    for (const AuxInfo *aux = (const AuxInfo *)_dlauxinfo();
      50         aux->a_type != AT_NULL; ++aux) {
      51      if (type == aux->a_type)
      52        return aux->a_v;
      53    }
      54  
      55    return 0;
      56  }
      57  
      58  #endif
      59  
      60  #endif // SANITIZER_GETAUXVAL_H