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 struct Checker {
29     char *cerr_mem_dump;
30     char *cin_mem_dump;
31     char *cout_mem_dump;
32     char *clog_mem_dump;
33 
34     char *wcerr_mem_dump;
35     char *wcin_mem_dump;
36     char *wcout_mem_dump;
37     char *wclog_mem_dump;
38 
39     Checker()
40         : cerr_mem_dump(new char[sizeof(std::cerr)])
41         , cin_mem_dump(new char[sizeof(std::cin)])
42         , cout_mem_dump(new char[sizeof(std::cout)])
43         , clog_mem_dump(new char[sizeof(std::clog)])
44 
45         , wcerr_mem_dump(new char[sizeof(std::wcerr)])
46         , wcin_mem_dump(new char[sizeof(std::wcin)])
47         , wcout_mem_dump(new char[sizeof(std::wcout)])
48         , wclog_mem_dump(new char[sizeof(std::wclog)])
49      {
50         std::memcpy(cerr_mem_dump, (char*)&std::cerr, sizeof(std::cerr));
51         std::memcpy(cin_mem_dump, (char*)&std::cin, sizeof(std::cin));
52         std::memcpy(cout_mem_dump, (char*)&std::cout, sizeof(std::cout));
53         std::memcpy(clog_mem_dump, (char*)&std::clog, sizeof(std::clog));
54 
55         std::memcpy(wcerr_mem_dump, (char*)&std::wcerr, sizeof(std::wcerr));
56         std::memcpy(wcin_mem_dump, (char*)&std::wcin, sizeof(std::wcin));
57         std::memcpy(wcout_mem_dump, (char*)&std::wcout, sizeof(std::wcout));
58         std::memcpy(wclog_mem_dump, (char*)&std::wclog, sizeof(std::wclog));
59     }
60 
61     ~Checker() {
62         delete[] cerr_mem_dump;
63         delete[] cin_mem_dump;
64         delete[] cout_mem_dump;
65         delete[] clog_mem_dump;
66 
67         delete[] wcerr_mem_dump;
68         delete[] wcin_mem_dump;
69         delete[] wcout_mem_dump;
70         delete[] wclog_mem_dump;
71     }
72 };
73 
74 static Checker check;
75 
76 int main(int, char**) {
77     assert(std::memcmp(check.cerr_mem_dump, (char const*)&std::cerr, sizeof(std::cerr)) == 0);
78     assert(std::memcmp(check.cin_mem_dump, (char const*)&std::cin, sizeof(std::cin)) == 0);
79     assert(std::memcmp(check.cout_mem_dump, (char const*)&std::cout, sizeof(std::cout)) == 0);
80     assert(std::memcmp(check.clog_mem_dump, (char const*)&std::clog, sizeof(std::clog)) == 0);
81 
82     assert(std::memcmp(check.wcerr_mem_dump, (char const*)&std::wcerr, sizeof(std::wcerr)) == 0);
83     assert(std::memcmp(check.wcin_mem_dump, (char const*)&std::wcin, sizeof(std::wcin)) == 0);
84     assert(std::memcmp(check.wcout_mem_dump, (char const*)&std::wcout, sizeof(std::wcout)) == 0);
85     assert(std::memcmp(check.wclog_mem_dump, (char const*)&std::wclog, sizeof(std::wclog)) == 0);
86     return 0;
87 }
88