Add crashpad_info, MachOImageAnnotationsReader, and its test

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>
+
+#if CXX_LIBRARY_VERSION >= 2011
+#include <type_traits>
+#endif
+
+namespace {
+
+static const uint32_t kCrashpadInfoVersion = 1;
+
+}  // namespace
+
+namespace crashpad {
+
+#if CXX_LIBRARY_VERSION >= 2011
+// 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