path: root/components/crash/content/app/breakpad_win.cc

// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/crash/content/app/breakpad_win.h"

#include <windows.h>
#include <shellapi.h>
#include <stddef.h>
#include <tchar.h>
#include <userenv.h>
#include <winnt.h>

#include <algorithm>
#include <map>
#include <vector>

#include "base/base_switches.h"
#include "base/command_line.h"
#include "base/debug/crash_logging.h"
#include "base/debug/dump_without_crashing.h"
#include "base/environment.h"
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/numerics/safe_conversions.h"
#include "base/strings/string16.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/strings/stringprintf.h"
#include "base/strings/utf_string_conversions.h"
#include "base/synchronization/lock.h"
#include "base/win/pe_image.h"
#include "base/win/registry.h"
#include "base/win/win_util.h"
#include "breakpad/src/client/windows/common/ipc_protocol.h"
#include "breakpad/src/client/windows/handler/exception_handler.h"
#include "components/crash/content/app/crash_keys_win.h"
#include "components/crash/content/app/crash_reporter_client.h"
#include "components/crash/content/app/hard_error_handler_win.h"
#include "components/crash/core/common/crash_keys.h"
#include "content/public/common/result_codes.h"
#include "sandbox/win/src/nt_internals.h"
#include "sandbox/win/src/sidestep/preamble_patcher.h"

// userenv.dll is required for GetProfileType().
#pragma comment(lib, "userenv.lib")

#pragma intrinsic(_AddressOfReturnAddress)
#pragma intrinsic(_ReturnAddress)

#ifdef _WIN64
// See http://msdn.microsoft.com/en-us/library/ddssxxy8.aspx
typedef struct _UNWIND_INFO {
  unsigned char Version : 3;
  unsigned char Flags : 5;
  unsigned char SizeOfProlog;
  unsigned char CountOfCodes;
  unsigned char FrameRegister : 4;
  unsigned char FrameOffset : 4;
  ULONG ExceptionHandler;
} UNWIND_INFO, *PUNWIND_INFO;
#endif

namespace breakpad {

using crash_reporter::GetCrashReporterClient;

namespace {

// Minidump with stacks, PEB, TEB, and unloaded module list.
const MINIDUMP_TYPE kSmallDumpType = static_cast<MINIDUMP_TYPE>(
    MiniDumpWithProcessThreadData |  // Get PEB and TEB.
    MiniDumpWithUnloadedModules);  // Get unloaded modules when available.

// Minidump with all of the above, plus memory referenced from stack.
const MINIDUMP_TYPE kLargerDumpType = static_cast<MINIDUMP_TYPE>(
    MiniDumpWithProcessThreadData |  // Get PEB and TEB.
    MiniDumpWithUnloadedModules |  // Get unloaded modules when available.
    MiniDumpWithIndirectlyReferencedMemory);  // Get memory referenced by stack.

// Large dump with all process memory.
const MINIDUMP_TYPE kFullDumpType = static_cast<MINIDUMP_TYPE>(
    MiniDumpWithFullMemory |  // Full memory from process.
    MiniDumpWithProcessThreadData |  // Get PEB and TEB.
    MiniDumpWithHandleData |  // Get all handle information.
    MiniDumpWithUnloadedModules);  // Get unloaded modules when available.

const char kPipeNameVar[] = "CHROME_BREAKPAD_PIPE_NAME";

const wchar_t kGoogleUpdatePipeName[] = L"\\\\.\\pipe\\GoogleCrashServices\\";
const wchar_t kChromePipeName[] = L"\\\\.\\pipe\\ChromeCrashServices";

// This is the well known SID for the system principal.
const wchar_t kSystemPrincipalSid[] =L"S-1-5-18";

google_breakpad::ExceptionHandler* g_breakpad = NULL;
google_breakpad::ExceptionHandler* g_dumphandler_no_crash = NULL;

#if !defined(_WIN64)
EXCEPTION_POINTERS g_surrogate_exception_pointers = {0};
EXCEPTION_RECORD g_surrogate_exception_record = {0};
CONTEXT g_surrogate_context = {0};
#endif  // !defined(_WIN64)

typedef NTSTATUS (WINAPI* NtTerminateProcessPtr)(HANDLE ProcessHandle,
                                                 NTSTATUS ExitStatus);
char* g_real_terminate_process_stub = NULL;

}  // namespace

// Dumps the current process memory.
extern "C" void __declspec(dllexport) __cdecl DumpProcess() {
  if (g_breakpad) {
    g_breakpad->WriteMinidump();
  }
}

// Used for dumping a process state when there is no crash.
extern "C" void __declspec(dllexport) __cdecl DumpProcessWithoutCrash() {
  if (g_dumphandler_no_crash) {
    g_dumphandler_no_crash->WriteMinidump();
  }
}

namespace {

// We need to prevent ICF from folding DumpForHangDebuggingThread() and
// DumpProcessWithoutCrashThread() together, since that makes them
// indistinguishable in crash dumps. We do this by making the function
// bodies unique, and prevent optimization from shuffling things around.
MSVC_DISABLE_OPTIMIZE()
MSVC_PUSH_DISABLE_WARNING(4748)

DWORD WINAPI DumpProcessWithoutCrashThread(void*) {
  DumpProcessWithoutCrash();
  return 0;
}

// The following two functions do exactly the same thing as the two above. But
// we want the signatures to be different so that we can easily track them in
// crash reports.
// TODO(yzshen): Remove when enough information is collected and the hang rate
// of pepper/renderer processes is reduced.
DWORD WINAPI DumpForHangDebuggingThread(void*) {
  DumpProcessWithoutCrash();
  VLOG(1) << "dumped for hang debugging";
  return 0;
}

MSVC_POP_WARNING()
MSVC_ENABLE_OPTIMIZE()

}  // namespace

// Injects a thread into a remote process to dump state when there is no crash.
extern "C" HANDLE __declspec(dllexport) __cdecl
InjectDumpProcessWithoutCrash(HANDLE process) {
  return CreateRemoteThread(process, NULL, 0, DumpProcessWithoutCrashThread,
                            0, 0, NULL);
}

extern "C" HANDLE __declspec(dllexport) __cdecl
InjectDumpForHangDebugging(HANDLE process) {
  return CreateRemoteThread(process, NULL, 0, DumpForHangDebuggingThread,
                            0, 0, NULL);
}

// Returns a string containing a list of all modifiers for the loaded profile.
std::wstring GetProfileType() {
  std::wstring profile_type;
  DWORD profile_bits = 0;
  if (::GetProfileType(&profile_bits)) {
    static const struct {
      DWORD bit;
      const wchar_t* name;
    } kBitNames[] = {
      { PT_MANDATORY, L"mandatory" },
      { PT_ROAMING, L"roaming" },
      { PT_TEMPORARY, L"temporary" },
    };
    for (size_t i = 0; i < arraysize(kBitNames); ++i) {
      const DWORD this_bit = kBitNames[i].bit;
      if ((profile_bits & this_bit) != 0) {
        profile_type.append(kBitNames[i].name);
        profile_bits &= ~this_bit;
        if (profile_bits != 0)
          profile_type.append(L", ");
      }
    }
  } else {
    DWORD last_error = ::GetLastError();
    base::SStringPrintf(&profile_type, L"error %u", last_error);
  }
  return profile_type;
}

namespace {

// This callback is used when we want to get a dump without crashing the
// process.
bool DumpDoneCallbackWhenNoCrash(const wchar_t*, const wchar_t*, void*,
                                 EXCEPTION_POINTERS* ex_info,
                                 MDRawAssertionInfo*, bool succeeded) {
  GetCrashReporterClient()->RecordCrashDumpAttemptResult(
      false /* is_real_crash */, succeeded);
  return true;
}

// This callback is executed when the browser process has crashed, after
// the crash dump has been created. We need to minimize the amount of work
// done here since we have potentially corrupted process. Our job is to
// spawn another instance of chrome which will show a 'chrome has crashed'
// dialog. This code needs to live in the exe and thus has no access to
// facilities such as the i18n helpers.
bool DumpDoneCallback(const wchar_t*, const wchar_t*, void*,
                      EXCEPTION_POINTERS* ex_info,
                      MDRawAssertionInfo*, bool succeeded) {
  GetCrashReporterClient()->RecordCrashDumpAttemptResult(
      true /* is_real_crash */, succeeded);
  // Check if the exception is one of the kind which would not be solved
  // by simply restarting chrome. In this case we show a message box with
  // and exit silently. Remember that chrome is in a crashed state so we
  // can't show our own UI from this process.
  if (HardErrorHandler(ex_info))
    return true;

  if (!GetCrashReporterClient()->AboutToRestart())
    return true;

  // Now we just start chrome browser with the same command line.
  STARTUPINFOW si = {sizeof(si)};
  PROCESS_INFORMATION pi;
  if (::CreateProcessW(NULL, ::GetCommandLineW(), NULL, NULL, FALSE,
                       CREATE_UNICODE_ENVIRONMENT, NULL, NULL, &si, &pi)) {
    ::CloseHandle(pi.hProcess);
    ::CloseHandle(pi.hThread);
  }
  // After this return we will be terminated. The actual return value is
  // not used at all.
  return true;
}

// flag to indicate that we are already handling an exception.
volatile LONG handling_exception = 0;

// This callback is used when there is no crash. Note: Unlike the
// |FilterCallback| below this does not do dupe detection. It is upto the caller
// to implement it.
bool FilterCallbackWhenNoCrash(
    void*, EXCEPTION_POINTERS*, MDRawAssertionInfo*) {
  GetCrashReporterClient()->RecordCrashDumpAttempt(false);
  return true;
}

// This callback is executed when the Chrome process has crashed and *before*
// the crash dump is created. To prevent duplicate crash reports we
// make every thread calling this method, except the very first one,
// go to sleep.
bool FilterCallback(void*, EXCEPTION_POINTERS*, MDRawAssertionInfo*) {
  // Capture every thread except the first one in the sleep. We don't
  // want multiple threads to concurrently report exceptions.
  if (::InterlockedCompareExchange(&handling_exception, 1, 0) == 1) {
    ::Sleep(INFINITE);
  }
  GetCrashReporterClient()->RecordCrashDumpAttempt(true);
  return true;
}

// Previous unhandled filter. Will be called if not null when we
// intercept a crash.
LPTOP_LEVEL_EXCEPTION_FILTER previous_filter = NULL;

// Exception filter used when breakpad is not enabled. We just display
// the "Do you want to restart" message and then we call the previous filter.
long WINAPI ChromeExceptionFilter(EXCEPTION_POINTERS* info) {
  DumpDoneCallback(NULL, NULL, NULL, info, NULL, false);

  if (previous_filter)
    return previous_filter(info);

  return EXCEPTION_EXECUTE_HANDLER;
}

// Exception filter for the service process used when breakpad is not enabled.
// We just display the "Do you want to restart" message and then die
// (without calling the previous filter).
long WINAPI ServiceExceptionFilter(EXCEPTION_POINTERS* info) {
  DumpDoneCallback(NULL, NULL, NULL, info, NULL, false);
  return EXCEPTION_EXECUTE_HANDLER;
}

#if !defined(COMPONENT_BUILD)
// Installed via base::debug::SetCrashKeyReportingFunctions.
void SetCrashKeyValueForBaseDebug(const base::StringPiece& key,
                                  const base::StringPiece& value) {
  DCHECK(CrashKeysWin::keeper());
  CrashKeysWin::keeper()->SetCrashKeyValue(base::UTF8ToUTF16(key),
                                           base::UTF8ToUTF16(value));
}

// Installed via base::debug::SetCrashKeyReportingFunctions.
void ClearCrashKeyForBaseDebug(const base::StringPiece& key) {
  DCHECK(CrashKeysWin::keeper());
  CrashKeysWin::keeper()->ClearCrashKeyValue(base::UTF8ToUTF16(key));
}
#endif  // !defined(COMPONENT_BUILD)

}  // namespace

// NOTE: This function is used by SyzyASAN to annotate crash reports. If you
// change the name or signature of this function you will break SyzyASAN
// instrumented releases of Chrome. Please contact syzygy-team@chromium.org
// before doing so!
extern "C" void __declspec(dllexport) __cdecl SetCrashKeyValueImpl(
    const wchar_t* key, const wchar_t* value) {
  CrashKeysWin* keeper = CrashKeysWin::keeper();
  if (!keeper)
    return;

  // TODO(siggi): This doesn't look quite right - there's NULL deref potential
  //    here, and an implicit std::wstring conversion. Fixme.
  keeper->SetCrashKeyValue(key, value);
}

extern "C" void __declspec(dllexport) __cdecl ClearCrashKeyValueImpl(
    const wchar_t* key) {
  CrashKeysWin* keeper = CrashKeysWin::keeper();
  if (!keeper)
    return;

  // TODO(siggi): This doesn't look quite right - there's NULL deref potential
  //    here, and an implicit std::wstring conversion. Fixme.
  keeper->ClearCrashKeyValue(key);
}

static bool WrapMessageBoxWithSEH(const wchar_t* text, const wchar_t* caption,
                                  UINT flags, bool* exit_now) {
  // We wrap the call to MessageBoxW with a SEH handler because it some
  // machines with CursorXP, PeaDict or with FontExplorer installed it crashes
  // uncontrollably here. Being this a best effort deal we better go away.
  __try {
    *exit_now = (IDOK != ::MessageBoxW(NULL, text, caption, flags));
  } __except(EXCEPTION_EXECUTE_HANDLER) {
    // Its not safe to continue executing, exit silently here.
    ::TerminateProcess(::GetCurrentProcess(),
                       GetCrashReporterClient()->GetResultCodeRespawnFailed());
  }

  return true;
}

// This function is executed by the child process that DumpDoneCallback()
// spawned and basically just shows the 'chrome has crashed' dialog if
// the CHROME_CRASHED environment variable is present.
bool ShowRestartDialogIfCrashed(bool* exit_now) {
  base::string16 message;
  base::string16 title;
  bool is_rtl_locale;
  if (!GetCrashReporterClient()->ShouldShowRestartDialog(
          &title, &message, &is_rtl_locale)) {
    return false;
  }

  // If the UI layout is right-to-left, we need to pass the appropriate MB_XXX
  // flags so that an RTL message box is displayed.
  UINT flags = MB_OKCANCEL | MB_ICONWARNING;
  if (is_rtl_locale)
    flags |= MB_RIGHT | MB_RTLREADING;

  return WrapMessageBoxWithSEH(message.c_str(), title.c_str(), flags, exit_now);
}

extern "C" void __declspec(dllexport) TerminateProcessWithoutDump() {
  // Patched stub exists based on conditions (See InitCrashReporter).
  // As a side note this function also gets called from
  // WindowProcExceptionFilter.
  if (g_real_terminate_process_stub == NULL) {
    ::TerminateProcess(::GetCurrentProcess(), content::RESULT_CODE_KILLED);
  } else {
    NtTerminateProcessPtr real_terminate_proc =
        reinterpret_cast<NtTerminateProcessPtr>(
            static_cast<char*>(g_real_terminate_process_stub));
    real_terminate_proc(::GetCurrentProcess(), content::RESULT_CODE_KILLED);
  }
}

// Crashes the process after generating a dump for the provided exception. Note
// that the crash reporter should be initialized before calling this function
// for it to do anything.
// NOTE: This function is used by SyzyASAN to invoke a crash. If you change the
// the name or signature of this function you will break SyzyASAN instrumented
// releases of Chrome. Please contact syzygy-team@chromium.org before doing so!
extern "C" int __declspec(dllexport) CrashForException(
    EXCEPTION_POINTERS* info) {
  if (g_breakpad) {
    g_breakpad->WriteMinidumpForException(info);
    TerminateProcessWithoutDump();
  }
  return EXCEPTION_CONTINUE_SEARCH;
}

#ifndef _WIN64
static NTSTATUS WINAPI HookNtTerminateProcess(HANDLE ProcessHandle,
                                              NTSTATUS ExitStatus) {
  if (g_breakpad &&
      (ProcessHandle == ::GetCurrentProcess() || ProcessHandle == NULL)) {
    NT_TIB* tib = reinterpret_cast<NT_TIB*>(NtCurrentTeb());
    void* address_on_stack = _AddressOfReturnAddress();
    if (address_on_stack < tib->StackLimit ||
        address_on_stack > tib->StackBase) {
      g_surrogate_exception_record.ExceptionAddress = _ReturnAddress();
      g_surrogate_exception_record.ExceptionCode = DBG_TERMINATE_PROCESS;
      g_surrogate_exception_record.ExceptionFlags = EXCEPTION_NONCONTINUABLE;
      CrashForException(&g_surrogate_exception_pointers);
    }
  }

  NtTerminateProcessPtr real_proc =
      reinterpret_cast<NtTerminateProcessPtr>(
          static_cast<char*>(g_real_terminate_process_stub));
  return real_proc(ProcessHandle, ExitStatus);
}

static void InitTerminateProcessHooks() {
  NtTerminateProcessPtr terminate_process_func_address =
      reinterpret_cast<NtTerminateProcessPtr>(::GetProcAddress(
          ::GetModuleHandle(L"ntdll.dll"), "NtTerminateProcess"));
  if (terminate_process_func_address == NULL)
    return;

  DWORD old_protect = 0;
  if (!::VirtualProtect(terminate_process_func_address, 5,
                        PAGE_EXECUTE_READWRITE, &old_protect))
    return;

  g_real_terminate_process_stub = reinterpret_cast<char*>(VirtualAllocEx(
      ::GetCurrentProcess(), NULL, sidestep::kMaxPreambleStubSize,
      MEM_COMMIT, PAGE_EXECUTE_READWRITE));
  if (g_real_terminate_process_stub == NULL)
    return;

  g_surrogate_exception_pointers.ContextRecord = &g_surrogate_context;
  g_surrogate_exception_pointers.ExceptionRecord =
      &g_surrogate_exception_record;

  sidestep::SideStepError patch_result =
      sidestep::PreamblePatcher::Patch(
          terminate_process_func_address, HookNtTerminateProcess,
          g_real_terminate_process_stub, sidestep::kMaxPreambleStubSize);
  if (patch_result != sidestep::SIDESTEP_SUCCESS) {
    CHECK(::VirtualFreeEx(::GetCurrentProcess(), g_real_terminate_process_stub,
                    0, MEM_RELEASE));
    CHECK(::VirtualProtect(terminate_process_func_address, 5, old_protect,
                           &old_protect));
    return;
  }

  DWORD dummy = 0;
  CHECK(::VirtualProtect(terminate_process_func_address,
                         5,
                         old_protect,
                         &dummy));
  CHECK(::VirtualProtect(g_real_terminate_process_stub,
                         sidestep::kMaxPreambleStubSize,
                         old_protect,
                         &old_protect));
}
#endif

static void InitPipeNameEnvVar(bool is_per_user_install) {
  scoped_ptr<base::Environment> env(base::Environment::Create());
  if (env->HasVar(kPipeNameVar)) {
    // The Breakpad pipe name is already configured: nothing to do.
    return;
  }

  // Check whether configuration management controls crash reporting.
  bool crash_reporting_enabled = true;
  bool controlled_by_policy =
      GetCrashReporterClient()->ReportingIsEnforcedByPolicy(
          &crash_reporting_enabled);

  const base::CommandLine& command = *base::CommandLine::ForCurrentProcess();
  bool use_crash_service = !controlled_by_policy &&
                           (command.HasSwitch(switches::kNoErrorDialogs) ||
                            GetCrashReporterClient()->IsRunningUnattended());

  std::wstring pipe_name;
  if (use_crash_service) {
    // Crash reporting is done by crash_service.exe.
    pipe_name = kChromePipeName;
  } else {
    // We want to use the Google Update crash reporting. We need to check if the
    // user allows it first (in case the administrator didn't already decide
    // via policy).
    if (!controlled_by_policy)
      crash_reporting_enabled =
          GetCrashReporterClient()->GetCollectStatsConsent();

    if (!crash_reporting_enabled) {
      // Crash reporting is disabled, don't set the environment variable.
      return;
    }

    // Build the pipe name. It can be either:
    // System-wide install: "NamedPipe\GoogleCrashServices\S-1-5-18"
    // Per-user install: "NamedPipe\GoogleCrashServices\<user SID>"
    std::wstring user_sid;
    if (is_per_user_install) {
      if (!base::win::GetUserSidString(&user_sid)) {
        return;
      }
    } else {
      user_sid = kSystemPrincipalSid;
    }

    pipe_name = kGoogleUpdatePipeName;
    pipe_name += user_sid;
  }
  env->SetVar(kPipeNameVar, base::UTF16ToASCII(pipe_name));
}

void InitDefaultCrashCallback(LPTOP_LEVEL_EXCEPTION_FILTER filter) {
  previous_filter = SetUnhandledExceptionFilter(filter);
}

void InitCrashReporter(const std::string& process_type_switch) {
  // The maximum lengths specified by breakpad include the trailing NULL, so the
  // actual length of the chunk is one less.
  static_assert(google_breakpad::CustomInfoEntry::kValueMaxLength - 1 ==
                crash_keys::kChunkMaxLength, "kChunkMaxLength mismatch");
  static_assert(crash_keys::kSmallSize <= crash_keys::kChunkMaxLength,
                "crash key chunk size too small");
  const base::CommandLine& command = *base::CommandLine::ForCurrentProcess();
  if (command.HasSwitch(switches::kDisableBreakpad))
    return;

  // Disable the message box for assertions.
  _CrtSetReportMode(_CRT_ASSERT, 0);

  base::string16 process_type = base::ASCIIToUTF16(process_type_switch);
  if (process_type.empty())
    process_type = L"browser";

  wchar_t exe_path[MAX_PATH];
  exe_path[0] = 0;
  GetModuleFileNameW(NULL, exe_path, MAX_PATH);

  bool is_per_user_install =
      GetCrashReporterClient()->GetIsPerUserInstall(base::FilePath(exe_path));

  // This is intentionally leaked.
  CrashKeysWin* keeper = new CrashKeysWin();

  google_breakpad::CustomClientInfo* custom_info =
      keeper->GetCustomInfo(exe_path, process_type, GetProfileType(),
                            base::CommandLine::ForCurrentProcess(),
                            GetCrashReporterClient());

#if !defined(COMPONENT_BUILD)
  // chrome/common/child_process_logging_win.cc registers crash keys for
  // chrome.dll. In a component build, that is sufficient as chrome.dll and
  // chrome.exe share a copy of base (in base.dll).
  // In a static build, the EXE must separately initialize the crash keys
  // configuration as it has its own statically linked copy of base.
  base::debug::SetCrashKeyReportingFunctions(&SetCrashKeyValueForBaseDebug,
                                             &ClearCrashKeyForBaseDebug);
  GetCrashReporterClient()->RegisterCrashKeys();
#endif

  google_breakpad::ExceptionHandler::MinidumpCallback callback = NULL;
  LPTOP_LEVEL_EXCEPTION_FILTER default_filter = NULL;
  // We install the post-dump callback only for the browser and service
  // processes. It spawns a new browser/service process.
  if (process_type == L"browser") {
    callback = &DumpDoneCallback;
    default_filter = &ChromeExceptionFilter;
  } else if (process_type == L"service") {
    callback = &DumpDoneCallback;
    default_filter = &ServiceExceptionFilter;
  }

  if (GetCrashReporterClient()->ShouldCreatePipeName(process_type))
    InitPipeNameEnvVar(is_per_user_install);

  if (process_type == L"browser")
    GetCrashReporterClient()->InitBrowserCrashDumpsRegKey();

  scoped_ptr<base::Environment> env(base::Environment::Create());
  std::string pipe_name_ascii;
  if (!env->GetVar(kPipeNameVar, &pipe_name_ascii)) {
    // Breakpad is not enabled.  Configuration is managed or the user
    // did not allow Google Update to send crashes.  We need to use
    // our default crash handler instead, but only for the
    // browser/service processes.
    if (default_filter)
      InitDefaultCrashCallback(default_filter);
    return;
  }
  base::string16 pipe_name = base::ASCIIToUTF16(pipe_name_ascii);

#ifdef _WIN64
  // The protocol for connecting to the out-of-process Breakpad crash
  // reporter is different for x86-32 and x86-64: the message sizes
  // are different because the message struct contains a pointer.  As
  // a result, there are two different named pipes to connect to.  The
  // 64-bit one is distinguished with an "-x64" suffix.
  pipe_name += L"-x64";
#endif

  // Get the alternate dump directory. We use the temp path.
  wchar_t temp_dir[MAX_PATH] = {0};
  ::GetTempPathW(MAX_PATH, temp_dir);

  MINIDUMP_TYPE dump_type = kSmallDumpType;
  // Capture full memory if explicitly instructed to.
  if (command.HasSwitch(switches::kFullMemoryCrashReport))
    dump_type = kFullDumpType;
  else if (GetCrashReporterClient()->GetShouldDumpLargerDumps(
               is_per_user_install))
    dump_type = kLargerDumpType;

  g_breakpad = new google_breakpad::ExceptionHandler(temp_dir, &FilterCallback,
                   callback, NULL,
                   google_breakpad::ExceptionHandler::HANDLER_ALL,
                   dump_type, pipe_name.c_str(), custom_info);

  // Now initialize the non crash dump handler.
  g_dumphandler_no_crash = new google_breakpad::ExceptionHandler(temp_dir,
      &FilterCallbackWhenNoCrash,
      &DumpDoneCallbackWhenNoCrash,
      NULL,
      // Set the handler to none so this handler would not be added to
      // |handler_stack_| in |ExceptionHandler| which is a list of exception
      // handlers.
      google_breakpad::ExceptionHandler::HANDLER_NONE,
      dump_type, pipe_name.c_str(), custom_info);

  // Set the DumpWithoutCrashingFunction for this instance of base.lib.  Other
  // executable images linked with base should set this again for
  // DumpWithoutCrashing to function correctly.
  // See chrome_main.cc for example.
  base::debug::SetDumpWithoutCrashingFunction(&DumpProcessWithoutCrash);

  if (g_breakpad->IsOutOfProcess()) {
    // Tells breakpad to handle breakpoint and single step exceptions.
    // This might break JIT debuggers, but at least it will always
    // generate a crashdump for these exceptions.
    g_breakpad->set_handle_debug_exceptions(true);

#ifndef _WIN64
    if (process_type != L"browser" &&
        !GetCrashReporterClient()->IsRunningUnattended()) {
      // Initialize the hook TerminateProcess to catch unexpected exits.
      InitTerminateProcessHooks();
    }
#endif
  }
}

void ConsumeInvalidHandleExceptions() {
  if (g_breakpad) {
    g_breakpad->set_consume_invalid_handle_exceptions(true);
  }
  if (g_dumphandler_no_crash) {
    g_dumphandler_no_crash->set_consume_invalid_handle_exceptions(true);
  }
}

// If the user has disabled crash reporting uploads and restarted Chrome, the
// restarted instance will still contain the pipe environment variable, which
// will allow the restarted process to still upload crash reports. This function
// clears the environment variable, so that the restarted Chrome, which inherits
// its environment from the current Chrome, will no longer contain the variable.
extern "C" void __declspec(dllexport) __cdecl
      ClearBreakpadPipeEnvironmentVariable() {
  scoped_ptr<base::Environment> env(base::Environment::Create());
  env->UnSetVar(kPipeNameVar);
}

#ifdef _WIN64
int CrashForExceptionInNonABICompliantCodeRange(
    PEXCEPTION_RECORD ExceptionRecord,
    ULONG64 EstablisherFrame,
    PCONTEXT ContextRecord,
    PDISPATCHER_CONTEXT DispatcherContext) {
  EXCEPTION_POINTERS info = { ExceptionRecord, ContextRecord };
  return CrashForException(&info);
}

struct ExceptionHandlerRecord {
  RUNTIME_FUNCTION runtime_function;
  UNWIND_INFO unwind_info;
  unsigned char thunk[12];
};

extern "C" void __declspec(dllexport) __cdecl
RegisterNonABICompliantCodeRange(void* start, size_t size_in_bytes) {
  ExceptionHandlerRecord* record =
      reinterpret_cast<ExceptionHandlerRecord*>(start);

  // We assume that the first page of the code range is executable and
  // committed and reserved for breakpad. What could possibly go wrong?

  // All addresses are 32bit relative offsets to start.
  record->runtime_function.BeginAddress = 0;
  record->runtime_function.EndAddress =
      base::checked_cast<DWORD>(size_in_bytes);
  record->runtime_function.UnwindData =
      offsetof(ExceptionHandlerRecord, unwind_info);

  // Create unwind info that only specifies an exception handler.
  record->unwind_info.Version = 1;
  record->unwind_info.Flags = UNW_FLAG_EHANDLER;
  record->unwind_info.SizeOfProlog = 0;
  record->unwind_info.CountOfCodes = 0;
  record->unwind_info.FrameRegister = 0;
  record->unwind_info.FrameOffset = 0;
  record->unwind_info.ExceptionHandler =
      offsetof(ExceptionHandlerRecord, thunk);

  // Hardcoded thunk.
  // mov imm64, rax
  record->thunk[0] = 0x48;
  record->thunk[1] = 0xb8;
  void* handler = &CrashForExceptionInNonABICompliantCodeRange;
  memcpy(&record->thunk[2], &handler, 8);

  // jmp rax
  record->thunk[10] = 0xff;
  record->thunk[11] = 0xe0;

  // Protect reserved page against modifications.
  DWORD old_protect;
  CHECK(VirtualProtect(
      start, sizeof(ExceptionHandlerRecord), PAGE_EXECUTE_READ, &old_protect));
  CHECK(RtlAddFunctionTable(
      &record->runtime_function, 1, reinterpret_cast<DWORD64>(start)));
}

extern "C" void __declspec(dllexport) __cdecl
UnregisterNonABICompliantCodeRange(void* start) {
  ExceptionHandlerRecord* record =
      reinterpret_cast<ExceptionHandlerRecord*>(start);

  CHECK(RtlDeleteFunctionTable(&record->runtime_function));
}
#endif

}  // namespace breakpad