245 lines
9.8 KiB
C++
245 lines
9.8 KiB
C++
// Copyright 2014 The Crashpad Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "handler/mac/exception_handler_server.h"
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#include <utility>
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#include "base/logging.h"
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#include "base/mac/mach_logging.h"
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#include "util/mach/composite_mach_message_server.h"
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#include "util/mach/mach_extensions.h"
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#include "util/mach/mach_message.h"
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#include "util/mach/mach_message_server.h"
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#include "util/mach/notify_server.h"
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namespace crashpad {
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namespace {
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class ExceptionHandlerServerRun : public UniversalMachExcServer::Interface,
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public NotifyServer::DefaultInterface {
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public:
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ExceptionHandlerServerRun(
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mach_port_t exception_port,
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mach_port_t notify_port,
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bool launchd,
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UniversalMachExcServer::Interface* exception_interface)
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: UniversalMachExcServer::Interface(),
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NotifyServer::DefaultInterface(),
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mach_exc_server_(this),
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notify_server_(this),
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composite_mach_message_server_(),
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exception_interface_(exception_interface),
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exception_port_(exception_port),
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notify_port_(notify_port),
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running_(true),
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launchd_(launchd) {
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composite_mach_message_server_.AddHandler(&mach_exc_server_);
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composite_mach_message_server_.AddHandler(¬ify_server_);
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}
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ExceptionHandlerServerRun(const ExceptionHandlerServerRun&) = delete;
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ExceptionHandlerServerRun& operator=(const ExceptionHandlerServerRun&) =
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delete;
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~ExceptionHandlerServerRun() {
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}
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void Run() {
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DCHECK(running_);
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kern_return_t kr;
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if (!launchd_) {
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// Request that a no-senders notification for exception_port_ be sent to
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// notify_port_.
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mach_port_t previous;
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kr = mach_port_request_notification(mach_task_self(),
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exception_port_,
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MACH_NOTIFY_NO_SENDERS,
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0,
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notify_port_,
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MACH_MSG_TYPE_MAKE_SEND_ONCE,
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&previous);
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MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_request_notification";
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base::mac::ScopedMachSendRight previous_owner(previous);
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}
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// A single CompositeMachMessageServer will dispatch both exception messages
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// and the no-senders notification. Put both receive rights into a port set.
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//
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// A single receive right can’t be used because the notification request
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// requires a send-once right, which would prevent the no-senders condition
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// from ever existing. Using distinct receive rights also allows the handler
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// methods to ensure that the messages they process were sent by a holder of
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// the proper send right.
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base::mac::ScopedMachPortSet server_port_set(
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NewMachPort(MACH_PORT_RIGHT_PORT_SET));
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CHECK(server_port_set.is_valid());
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kr = mach_port_insert_member(
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mach_task_self(), exception_port_, server_port_set.get());
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MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_insert_member";
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kr = mach_port_insert_member(
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mach_task_self(), notify_port_, server_port_set.get());
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MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_insert_member";
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// Run the server in kOneShot mode so that running_ can be reevaluated after
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// each message. Receipt of a valid no-senders notification causes it to be
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// set to false.
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while (running_) {
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// This will result in a call to CatchMachException() or
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// DoMachNotifyNoSenders() as appropriate.
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mach_msg_return_t mr =
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MachMessageServer::Run(&composite_mach_message_server_,
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server_port_set.get(),
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kMachMessageReceiveAuditTrailer,
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MachMessageServer::kOneShot,
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MachMessageServer::kReceiveLargeIgnore,
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kMachMessageTimeoutWaitIndefinitely);
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// MACH_SEND_INVALID_DEST occurs when attempting to reply to a dead name.
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// This can happen if a mach_exc or exc client disappears before a reply
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// can be sent to it. That’s unusal for kernel-generated requests, but can
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// easily happen if a task sends its own exception request (as
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// SimulateCrash() does) and dies before the reply is sent.
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MACH_CHECK(mr == MACH_MSG_SUCCESS || mr == MACH_SEND_INVALID_DEST, mr)
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<< "MachMessageServer::Run";
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}
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}
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// UniversalMachExcServer::Interface:
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kern_return_t CatchMachException(exception_behavior_t behavior,
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exception_handler_t exception_port,
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thread_t thread,
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task_t task,
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exception_type_t exception,
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const mach_exception_data_type_t* code,
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mach_msg_type_number_t code_count,
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thread_state_flavor_t* flavor,
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ConstThreadState old_state,
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mach_msg_type_number_t old_state_count,
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thread_state_t new_state,
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mach_msg_type_number_t* new_state_count,
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const mach_msg_trailer_t* trailer,
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bool* destroy_complex_request) override {
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if (exception_port != exception_port_) {
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LOG(WARNING) << "exception port mismatch";
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return KERN_FAILURE;
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}
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return exception_interface_->CatchMachException(behavior,
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exception_port,
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thread,
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task,
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exception,
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code,
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code_count,
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flavor,
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old_state,
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old_state_count,
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new_state,
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new_state_count,
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trailer,
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destroy_complex_request);
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}
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// NotifyServer::DefaultInterface:
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kern_return_t DoMachNotifyNoSenders(
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notify_port_t notify,
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mach_port_mscount_t mscount,
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const mach_msg_trailer_t* trailer) override {
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if (notify != notify_port_) {
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// The message was received as part of a port set. This check ensures that
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// only the authorized sender of the no-senders notification is able to
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// stop the exception server. Otherwise, a malicious client would be able
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// to craft and send a no-senders notification via its exception port, and
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// cause the handler to stop processing exceptions and exit.
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LOG(WARNING) << "notify port mismatch";
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return KERN_FAILURE;
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}
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running_ = false;
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return KERN_SUCCESS;
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}
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private:
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UniversalMachExcServer mach_exc_server_;
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NotifyServer notify_server_;
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CompositeMachMessageServer composite_mach_message_server_;
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UniversalMachExcServer::Interface* exception_interface_; // weak
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mach_port_t exception_port_; // weak
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mach_port_t notify_port_; // weak
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bool running_;
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bool launchd_;
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};
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} // namespace
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ExceptionHandlerServer::ExceptionHandlerServer(
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base::mac::ScopedMachReceiveRight receive_port,
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bool launchd)
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: receive_port_(std::move(receive_port)),
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notify_port_(NewMachPort(MACH_PORT_RIGHT_RECEIVE)),
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launchd_(launchd) {
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CHECK(receive_port_.is_valid());
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CHECK(notify_port_.is_valid());
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}
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ExceptionHandlerServer::~ExceptionHandlerServer() {
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}
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void ExceptionHandlerServer::Run(
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UniversalMachExcServer::Interface* exception_interface) {
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ExceptionHandlerServerRun run(
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receive_port_.get(), notify_port_.get(), launchd_, exception_interface);
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run.Run();
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}
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void ExceptionHandlerServer::Stop() {
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// Cause the exception handler server to stop running by sending it a
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// synthesized no-senders notification.
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//
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// mach_no_senders_notification_t defines the receive side of this structure,
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// with a trailer element that’s undesirable for the send side.
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struct {
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mach_msg_header_t header;
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NDR_record_t ndr;
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mach_msg_type_number_t mscount;
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} no_senders_notification = {};
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no_senders_notification.header.msgh_bits =
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MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND_ONCE, 0);
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no_senders_notification.header.msgh_size = sizeof(no_senders_notification);
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no_senders_notification.header.msgh_remote_port = notify_port_.get();
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no_senders_notification.header.msgh_local_port = MACH_PORT_NULL;
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no_senders_notification.header.msgh_id = MACH_NOTIFY_NO_SENDERS;
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no_senders_notification.ndr = NDR_record;
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no_senders_notification.mscount = 0;
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kern_return_t kr = mach_msg(&no_senders_notification.header,
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MACH_SEND_MSG,
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sizeof(no_senders_notification),
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0,
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MACH_PORT_NULL,
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MACH_MSG_TIMEOUT_NONE,
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MACH_PORT_NULL);
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MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_msg";
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}
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} // namespace crashpad
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