crashpad/client/crashpad_info.cc

// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "client/crashpad_info.h"

#include <mach-o/loader.h>

#include "util/stdlib/cxx.h"

#if CXX_LIBRARY_VERSION >= 2011
#include <type_traits>
#endif

namespace {

static const uint32_t kCrashpadInfoVersion = 1;

}  // namespace

namespace crashpad {

#if CXX_LIBRARY_VERSION >= 2011 || DOXYGEN
// In C++11, check that CrashpadInfo has standard layout, which is what is
// actually important.
static_assert(std::is_standard_layout<CrashpadInfo>::value,
              "CrashpadInfo must be standard layout");
#else
// In C++98 (ISO 14882), section 9.5.1 says that a union cannot have a member
// with a non-trivial ctor, copy ctor, dtor, or assignment operator. Use this
// property to ensure that CrashpadInfo remains POD. This doesn’t work for C++11
// because the requirements for unions have been relaxed.
union Compile_Assert {
  CrashpadInfo Compile_Assert__CrashpadInfo_must_be_pod;
};
#endif

// Put the structure in __DATA,__crashpad_info where it can be easily found
// without having to consult the symbol table. The “used” attribute prevents it
// from being dead-stripped. This isn’t placed in an unnamed namespace:
// hopefully, this will catch attempts to place multiple copies of this
// structure into the same module. If that’s attempted, and the name of the
// symbol is the same in each translation unit, it will result in a linker
// error, which is better than having multiple structures show up.
//
// This may result in a static module initializer in debug-mode builds, but
// because it’s POD, no code should need to run to initialize this under
// release-mode optimization.
__attribute__((section(SEG_DATA ",__crashpad_info"),
               used,
               visibility("hidden"))) CrashpadInfo g_crashpad_info;

// static
CrashpadInfo* CrashpadInfo::GetCrashpadInfo() {
  return &g_crashpad_info;
}

CrashpadInfo::CrashpadInfo()
    : signature_(kSignature),
      size_(sizeof(*this)),
      version_(kCrashpadInfoVersion),
      padding_0_(0),
      simple_annotations_(nullptr) {
}

const uint32_t CrashpadInfo::kSignature;

}  // namespace crashpad