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 }
101