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