+
−/* This Source Code Form is subject to the terms of the Mozilla Public
+
− * License, v. 2.0. If a copy of the MPL was not distributed with this
+
− * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
−
+
−#include <ostream>
+
−#include <istream>
+
−#include <sstream>
+
−#include <memory>
+
−#include <string>
+
−#include <stdarg.h>
+
−#include <stdio.h>
+
−#include <mozilla/Assertions.h>
+
−#include <cxxabi.h>
+
−
+
−/*
+
−   GLIBCXX_3.4.19 is from gcc 4.8.1 (199309)
+
−   GLIBCXX_3.4.20 is from gcc 4.9.0 (199307)
+
−   GLIBCXX_3.4.21 is from gcc 5.0 (210290)
+
−   GLIBCXX_3.4.22 is from gcc 6.0 (222482)
+
−   GLIBCXX_3.4.23 is from gcc 7
+
−   GLIBCXX_3.4.24 is from gcc 8
+
−   GLIBCXX_3.4.25 is from gcc 8
+
−   GLIBCXX_3.4.26 is from gcc 9
+
−   GLIBCXX_3.4.27 is from gcc 10
+
−   GLIBCXX_3.4.28 is from gcc 10
+
−   GLIBCXX_3.4.29 is from gcc 11
+
−
+
−This file adds the necessary compatibility tricks to avoid symbols with
+
−version GLIBCXX_3.4.20 and bigger, keeping binary compatibility with
+
−libstdc++ 4.8.1.
+
−
+
−WARNING: all symbols from this file must be defined weak when they
+
−overlap with libstdc++.
+
−*/
+
−
+
−namespace std {
+
−
+
−/* We shouldn't be throwing exceptions at all, but it sadly turns out
+
−   we call STL (inline) functions that do. This avoids the GLIBCXX_3.4.20
+
−   symbol version. */
+
−void __attribute__((weak)) __throw_out_of_range_fmt(char const* fmt, ...) {
+
−  va_list ap;
+
−  char buf[1024];  // That should be big enough.
+
−
+
−  va_start(ap, fmt);
+
−  vsnprintf(buf, sizeof(buf), fmt, ap);
+
−  buf[sizeof(buf) - 1] = 0;
+
−  va_end(ap);
+
−
+
−  __throw_range_error(buf);
+
−}
+
−
+
−}  // namespace std
+
−
+
−namespace __cxxabiv1 {
+
−/* Calls to this function are added by the compiler itself on `new Class[n]`
+
− * calls. This avoids the GLIBCXX_3.4.20 symbol version. */
+
−extern "C" void __attribute__((weak)) __cxa_throw_bad_array_new_length() {
+
−  MOZ_CRASH();
+
−}
+
−}  // namespace __cxxabiv1
+
−
+
−#if _GLIBCXX_RELEASE >= 11
+
−namespace std {
+
−
+
−/* This avoids the GLIBCXX_3.4.29 symbol version. */
+
−void __attribute__((weak)) __throw_bad_array_new_length() { MOZ_CRASH(); }
+
−
+
−}  // namespace std
+
−#endif
+
−
+
−/* While we generally don't build with exceptions, we have some host tools
+
− * that do use them. libstdc++ from GCC 5.0 added exception constructors with
+
− * char const* argument. Older versions only have a constructor with
+
− * std::string. This avoids the GLIBCXX_3.4.21 symbol version. */
+
−namespace std {
+
−__attribute__((weak)) runtime_error::runtime_error(char const* s)
+
−    : runtime_error(std::string(s)) {}
+
−__attribute__((weak)) out_of_range::out_of_range(char const* s)
+
−    : out_of_range(std::string(s)) {}
+
−__attribute__((weak)) invalid_argument::invalid_argument(char const* s)
+
−    : invalid_argument(std::string(s)) {}
+
−}  // namespace std
+
−
+
−/* Expose the definitions for the old ABI, allowing us to call its functions */
+
−#define _GLIBCXX_THREAD_ABI_COMPAT 1
+
−#include <thread>
+
−
+
−namespace std {
+
−/* The old ABI has a thread::_M_start_thread(shared_ptr<_Impl_base>),
+
− * while the new has thread::_M_start_thread(unique_ptr<_State>, void(*)()).
+
− * There is an intermediate ABI at version 3.4.21, with
+
− * thread::_M_start_thread(shared_ptr<_Impl_base>, void(*)()).
+
− * The void(*)() parameter is only there to keep a reference to pthread_create
+
− * on the caller side, and is unused in the implementation
+
− * We're creating an entry point for the new and intermediate ABIs, and make
+
− * them call the old ABI. This avoids the GLIBCXX_3.4.21 symbol version. */
+
−__attribute__((weak)) void thread::_M_start_thread(shared_ptr<_Impl_base> impl,
+
−                                                   void (*)()) {
+
−  _M_start_thread(std::move(impl));
+
−}
+
−
+
−/* We need a _Impl_base-derived class wrapping a _State to call the old ABI
+
− * from what we got by diverting the new API. This avoids the GLIBCXX_3.4.22
+
− * symbol version. */
+
−struct StateWrapper : public thread::_Impl_base {
+
−  unique_ptr<thread::_State> mState;
+
−
+
−  StateWrapper(unique_ptr<thread::_State> aState) : mState(std::move(aState)) {}
+
−
+
−  void _M_run() override { mState->_M_run(); }
+
−};
+
−
+
−/* This avoids the GLIBCXX_3.4.22 symbol version. */
+
−__attribute__((weak)) void thread::_M_start_thread(unique_ptr<_State> aState,
+
−                                                   void (*)()) {
+
−  auto impl = std::make_shared<StateWrapper>(std::move(aState));
+
−  _M_start_thread(std::move(impl));
+
−}
+
−
+
−/* For some reason this is a symbol exported by new versions of libstdc++,
+
− * even though the destructor is default there too. This avoids the
+
− * GLIBCXX_3.4.22 symbol version. */
+
−__attribute__((weak)) thread::_State::~_State() = default;
+
−
+
−#if _GLIBCXX_RELEASE >= 9
+
−// Ideally we'd define
+
−//    bool _Sp_make_shared_tag::_S_eq(const type_info& ti) noexcept
+
−// but we wouldn't be able to change its visibility because of the existing
+
−// definition in C++ headers. We do need to change its visibility because we
+
−// don't want it to be shadowing the one provided by libstdc++ itself, because
+
−// it doesn't support RTTI. Not supporting RTTI doesn't matter for Firefox
+
−// itself because it's built with RTTI disabled.
+
−// So we define via the mangled symbol.
+
−// This avoids the GLIBCXX_3.4.26 symbol version.
+
−extern "C" __attribute__((visibility("hidden"))) bool
+
−_ZNSt19_Sp_make_shared_tag5_S_eqERKSt9type_info(const type_info*) noexcept {
+
−  return false;
+
−}
+
−#endif
+
−
+
−}  // namespace std
+
−
+
−namespace std {
+
−/* Instantiate this template to avoid GLIBCXX_3.4.21 symbol versions
+
− * depending on optimization level */
+
−template basic_ios<char, char_traits<char>>::operator bool() const;
+
−}  // namespace std
+
−
+
−#if !defined(MOZ_ASAN) && !defined(MOZ_TSAN)
+
−/* operator delete with size is only available in CXXAPI_1.3.9, equivalent to
+
− * GLIBCXX_3.4.21. */
+
−void operator delete(void* ptr, size_t size) noexcept(true) {
+
−  ::operator delete(ptr);
+
−}
+
−#endif
+
−
+
−namespace std {
+
−/* Instantiate this template to avoid GLIBCXX_3.4.23 symbol versions
+
− * depending on optimization level */
+
−template basic_string<char, char_traits<char>, allocator<char>>::basic_string(
+
−    const basic_string&, size_t, const allocator<char>&);
+
−
+
−#if _GLIBCXX_RELEASE >= 9
+
−// This avoids the GLIBCXX_3.4.26 symbol version.
+
−template basic_stringstream<char, char_traits<char>,
+
−                            allocator<char>>::basic_stringstream();
+
−
+
−template basic_ostringstream<char, char_traits<char>,
+
−                             allocator<char>>::basic_ostringstream();
+
−#endif
+
−
+
−#if _GLIBCXX_RELEASE >= 11
+
−// This avoids the GLIBCXX_3.4.29 symbol version.
+
−template void basic_string<char, char_traits<char>, allocator<char>>::reserve();
+
−
+
−template void
+
−basic_string<wchar_t, char_traits<wchar_t>, allocator<wchar_t>>::reserve();
+
−#endif
+
−
+
−}  // namespace std
+
−
+
−/* The __cxa_thread_atexit_impl symbol is only available on GLIBC 2.18, but we
+
− * want things to keep working on 2.17. It's not actually used directly from
+
− * C++ code, but through __cxa_thead_atexit in libstdc++. The problem we have,
+
− * though, is that rust's libstd also uses it, introducing a dependency we
+
− * don't actually want. Fortunately, we can fall back to libstdc++'s wrapper
+
− * (which, on systems without __cxa_thread_atexit_impl, has its own compatible
+
− * implementation).
+
− * The __cxa_thread_atexit symbol itself is marked CXXABI_1.3.7, which is
+
− * equivalent to GLIBCXX_3.4.18.
+
− */
+
−extern "C" int __cxa_thread_atexit_impl(void (*dtor)(void*), void* obj,
+
−                                        void* dso_handle) {
+
−  return __cxxabiv1::__cxa_thread_atexit(dtor, obj, dso_handle);
+
−}