libcxx/test/std/input.output/iostream.objects/init.pass.cpp

   1 //===----------------------------------------------------------------------===//
   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 // Make sure that the iostreams are initialized before everything else.
  10 // This has been an issue when statically linking libc++ in some contexts.
  11 // See https://llvm.org/PR28954 for details.
  12 //
  13 // This test works by checking that std::{cin,cout,cerr} is the same in a
  14 // static object constructor and in the main function. It dumps the memory of
  15 // each stream in the static object constructor and compares it with the memory
  16 // in the main function.
  17 //
  18 // The assumption is that if there are no uses of the stream object (such as
  19 // construction), then its memory must be the same. In the case where the test
  20 // "fails" and we are actually accessing an uninitialized object when we perform
  21 // the memcpy, the behavior is technically undefined (so the test could still
  22 // pass).
  23
  24 #include <cassert>
  25 #include <cstring>
  26 #include <iostream>
  27
  28 #include "test_macros.h"
  29
  30 struct Checker {
  31     char *cerr_mem_dump;
  32     char *cin_mem_dump;
  33     char *cout_mem_dump;
  34     char *clog_mem_dump;
  35
  36     Checker()
  37         : cerr_mem_dump(new char[sizeof(std::cerr)])
  38         , cin_mem_dump(new char[sizeof(std::cin)])
  39         , cout_mem_dump(new char[sizeof(std::cout)])
  40         , clog_mem_dump(new char[sizeof(std::clog)])
  41      {
  42         std::memcpy(cerr_mem_dump, (char*)&std::cerr, sizeof(std::cerr));
  43         std::memcpy(cin_mem_dump, (char*)&std::cin, sizeof(std::cin));
  44         std::memcpy(cout_mem_dump, (char*)&std::cout, sizeof(std::cout));
  45         std::memcpy(clog_mem_dump, (char*)&std::clog, sizeof(std::clog));
  46     }
  47
  48     ~Checker() {
  49         delete[] cerr_mem_dump;
  50         delete[] cin_mem_dump;
  51         delete[] cout_mem_dump;
  52         delete[] clog_mem_dump;
  53     }
  54 };
  55 static Checker check;
  56
  57 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  58 struct WideChecker {
  59     char *wcerr_mem_dump;
  60     char *wcin_mem_dump;
  61     char *wcout_mem_dump;
  62     char *wclog_mem_dump;
  63
  64     WideChecker()
  65         : wcerr_mem_dump(new char[sizeof(std::wcerr)])
  66         , wcin_mem_dump(new char[sizeof(std::wcin)])
  67         , wcout_mem_dump(new char[sizeof(std::wcout)])
  68         , wclog_mem_dump(new char[sizeof(std::wclog)])
  69      {
  70         std::memcpy(wcerr_mem_dump, (char*)&std::wcerr, sizeof(std::wcerr));
  71         std::memcpy(wcin_mem_dump, (char*)&std::wcin, sizeof(std::wcin));
  72         std::memcpy(wcout_mem_dump, (char*)&std::wcout, sizeof(std::wcout));
  73         std::memcpy(wclog_mem_dump, (char*)&std::wclog, sizeof(std::wclog));
  74     }
  75
  76     ~WideChecker() {
  77         delete[] wcerr_mem_dump;
  78         delete[] wcin_mem_dump;
  79         delete[] wcout_mem_dump;
  80         delete[] wclog_mem_dump;
  81     }
  82 };
  83
  84 static WideChecker wide_check;
  85 #endif
  86
  87 int main(int, char**) {
  88     assert(std::memcmp(check.cerr_mem_dump, (char const*)&std::cerr, sizeof(std::cerr)) == 0);
  89     assert(std::memcmp(check.cin_mem_dump, (char const*)&std::cin, sizeof(std::cin)) == 0);
  90     assert(std::memcmp(check.cout_mem_dump, (char const*)&std::cout, sizeof(std::cout)) == 0);
  91     assert(std::memcmp(check.clog_mem_dump, (char const*)&std::clog, sizeof(std::clog)) == 0);
  92
  93 #ifndef TEST_HAS_NO_WIDE_CHARACTERS
  94     assert(std::memcmp(wide_check.wcerr_mem_dump, (char const*)&std::wcerr, sizeof(std::wcerr)) == 0);
  95     assert(std::memcmp(wide_check.wcin_mem_dump, (char const*)&std::wcin, sizeof(std::wcin)) == 0);
  96     assert(std::memcmp(wide_check.wcout_mem_dump, (char const*)&std::wcout, sizeof(std::wcout)) == 0);
  97     assert(std::memcmp(wide_check.wclog_mem_dump, (char const*)&std::wclog, sizeof(std::wclog)) == 0);
  98 #endif
  99     return 0;
 100 }