win: Implement CRASHPAD_SIMULATE_CRASH()

snapshot/win/exception_snapshot_win.cc

 // Copyright 2015 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,
@@ skipping 116 matching lines @@
     const ProcessReaderWin& process_reader,
     WinVMAddress exception_pointers_address,
     ContextType* context_record) {
   ExceptionPointersType exception_pointers;
   if (!process_reader.ReadMemory(exception_pointers_address,
                                  sizeof(exception_pointers),
                                  &exception_pointers)) {
     LOG(ERROR) << "EXCEPTION_POINTERS read failed";
     return false;
   }
+
+  if (!process_reader.ReadMemory(
+          static_cast<WinVMAddress>(exception_pointers.ContextRecord),
+          sizeof(*context_record),
+          context_record)) {
+    LOG(ERROR) << "ContextRecord";
+    return false;
+  }
+
   if (!exception_pointers.ExceptionRecord) {
-    LOG(ERROR) << "null ExceptionRecord";
-    return false;
+    LOG(INFO) << "null ExceptionRecord, not capturing any exception";

[Mark Mentovai, 2015/09/23 20:00:52]

This is fully expected now, I don’t think we need to log anything when this
happens. But this should have a comment saying that it happens for simulated
crashes.

[scottmg, 2015/09/24 19:16:52]

Done.

+    return true;
   }
 
   ExceptionRecordType first_record;
   if (!process_reader.ReadMemory(
           static_cast<WinVMAddress>(exception_pointers.ExceptionRecord),
           sizeof(first_record),
           &first_record)) {
     LOG(ERROR) << "ExceptionRecord";
     return false;
   }
   exception_code_ = first_record.ExceptionCode;
   exception_flags_ = first_record.ExceptionFlags;
   exception_address_ = first_record.ExceptionAddress;
   for (DWORD i = 0; i < first_record.NumberParameters; ++i)
     codes_.push_back(first_record.ExceptionInformation[i]);
   if (first_record.ExceptionRecord) {
     // https://code.google.com/p/crashpad/issues/detail?id=43
     LOG(WARNING) << "dropping chained ExceptionRecord";
   }
 
-  if (!process_reader.ReadMemory(
-          static_cast<WinVMAddress>(exception_pointers.ContextRecord),
-          sizeof(*context_record),
-          context_record)) {
-    LOG(ERROR) << "ContextRecord";
-    return false;
-  }
-
   return true;
 }
 
 }  // namespace internal
 }  // namespace crashpad