This revision was not accepted when it landed; it landed in state "Needs Review". This revision was landed with ongoing or failed builds. This revision was automatically updated to reflect the committed changes. Closed by commit rG39faf428164a: [libc++] Ensure streams are initialized early (authored by ldionne).
Changed prior to commit: https://reviews.llvm.org/D31413?vs=292261&id=292262#toc Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D31413/new/ https://reviews.llvm.org/D31413 Files: libcxx/src/iostream.cpp libcxx/test/std/input.output/iostream.objects/init.pass.cpp
Index: libcxx/test/std/input.output/iostream.objects/init.pass.cpp =================================================================== --- /dev/null +++ libcxx/test/std/input.output/iostream.objects/init.pass.cpp @@ -0,0 +1,88 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// + +// UNSUPPORTED: libcpp-has-no-stdin, libcpp-has-no-stdout + +// Make sure that the iostreams are initialized before everything else. +// This has been an issue when statically linking libc++ in some contexts. +// See https://llvm.org/PR28954 for details. +// +// This test works by checking that std::{cin,cout,cerr} is the same in a +// static object constructor and in the main function. It dumps the memory of +// each stream in the static object constructor and compares it with the memory +// in the main function. +// +// The assumption is that if there are no uses of the stream object (such as +// construction), then its memory must be the same. In the case where the test +// "fails" and we are actually accessing an uninitialized object when we perform +// the memcpy, the behavior is technically undefined (so the test could still +// pass). + +#include <cassert> +#include <cstring> +#include <iostream> + +struct Checker { + char *cerr_mem_dump; + char *cin_mem_dump; + char *cout_mem_dump; + char *clog_mem_dump; + + char *wcerr_mem_dump; + char *wcin_mem_dump; + char *wcout_mem_dump; + char *wclog_mem_dump; + + Checker() + : cerr_mem_dump(new char[sizeof(std::cerr)]) + , cin_mem_dump(new char[sizeof(std::cin)]) + , cout_mem_dump(new char[sizeof(std::cout)]) + , clog_mem_dump(new char[sizeof(std::clog)]) + + , wcerr_mem_dump(new char[sizeof(std::wcerr)]) + , wcin_mem_dump(new char[sizeof(std::wcin)]) + , wcout_mem_dump(new char[sizeof(std::wcout)]) + , wclog_mem_dump(new char[sizeof(std::wclog)]) + { + std::memcpy(cerr_mem_dump, (char*)&std::cerr, sizeof(std::cerr)); + std::memcpy(cin_mem_dump, (char*)&std::cin, sizeof(std::cin)); + std::memcpy(cout_mem_dump, (char*)&std::cout, sizeof(std::cout)); + std::memcpy(clog_mem_dump, (char*)&std::clog, sizeof(std::clog)); + + std::memcpy(wcerr_mem_dump, (char*)&std::wcerr, sizeof(std::wcerr)); + std::memcpy(wcin_mem_dump, (char*)&std::wcin, sizeof(std::wcin)); + std::memcpy(wcout_mem_dump, (char*)&std::wcout, sizeof(std::wcout)); + std::memcpy(wclog_mem_dump, (char*)&std::wclog, sizeof(std::wclog)); + } + + ~Checker() { + delete[] cerr_mem_dump; + delete[] cin_mem_dump; + delete[] cout_mem_dump; + delete[] clog_mem_dump; + + delete[] wcerr_mem_dump; + delete[] wcin_mem_dump; + delete[] wcout_mem_dump; + delete[] wclog_mem_dump; + } +}; + +static Checker check; + +int main() { + assert(std::memcmp(check.cerr_mem_dump, (char const*)&std::cerr, sizeof(std::cerr)) == 0); + assert(std::memcmp(check.cin_mem_dump, (char const*)&std::cin, sizeof(std::cin)) == 0); + assert(std::memcmp(check.cout_mem_dump, (char const*)&std::cout, sizeof(std::cout)) == 0); + assert(std::memcmp(check.clog_mem_dump, (char const*)&std::clog, sizeof(std::clog)) == 0); + + assert(std::memcmp(check.wcerr_mem_dump, (char const*)&std::wcerr, sizeof(std::wcerr)) == 0); + assert(std::memcmp(check.wcin_mem_dump, (char const*)&std::wcin, sizeof(std::wcin)) == 0); + assert(std::memcmp(check.wcout_mem_dump, (char const*)&std::wcout, sizeof(std::wcout)) == 0); + assert(std::memcmp(check.wclog_mem_dump, (char const*)&std::wclog, sizeof(std::wclog)) == 0); +} Index: libcxx/src/iostream.cpp =================================================================== --- libcxx/src/iostream.cpp +++ libcxx/src/iostream.cpp @@ -77,7 +77,7 @@ #endif ; -_LIBCPP_HIDDEN ios_base::Init __start_std_streams; +_LIBCPP_HIDDEN ios_base::Init __start_std_streams __attribute__((init_priority(101))); // On Windows the TLS storage for locales needs to be initialized before we create // the standard streams, otherwise it may not be alive during program termination
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