mirror of
https://github.com/chromium/crashpad.git
synced 2025-03-10 06:36:02 +00:00
7413569ea6
The bug and linked code review has more of the history, but we’ve been tempted to remove the loop outright a couple of times already before realizing that it serves an important purpose. Hopefully this comment will protect our future selves from going on the same fool’s errand. BUG=crashpad:75 R=scottmg@chromium.org Review URL: https://codereview.chromium.org/1427643010 .
95 lines
3.4 KiB
C++
95 lines
3.4 KiB
C++
// 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,
|
||
// 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 "util/win/registration_protocol_win.h"
|
||
|
||
#include <windows.h>
|
||
|
||
#include "base/logging.h"
|
||
#include "util/win/scoped_handle.h"
|
||
|
||
namespace crashpad {
|
||
|
||
bool SendToCrashHandlerServer(const base::string16& pipe_name,
|
||
const crashpad::ClientToServerMessage& message,
|
||
crashpad::ServerToClientMessage* response) {
|
||
// Retry CreateFile() in a loop. If the handler isn’t actively waiting in
|
||
// ConnectNamedPipe() on a pipe instance because it’s busy doing something
|
||
// else, CreateFile() will fail with ERROR_PIPE_BUSY. WaitNamedPipe() waits
|
||
// until a pipe instance is ready, but there’s no way to wait for this
|
||
// condition and atomically open the client side of the pipe in a single
|
||
// operation. CallNamedPipe() implements similar retry logic to this, also in
|
||
// user-mode code.
|
||
//
|
||
// This loop is only intended to retry on ERROR_PIPE_BUSY. Notably, if the
|
||
// handler is so lazy that it hasn’t even called CreateNamedPipe() yet,
|
||
// CreateFile() will fail with ERROR_FILE_NOT_FOUND, and this function is
|
||
// expected to fail without retrying anything. If the handler is started at
|
||
// around the same time as its client, something external to this code must be
|
||
// done to guarantee correct ordering. When the client starts the handler
|
||
// itself, CrashpadClient::StartHandler() provides this synchronization.
|
||
for (int tries = 0;;) {
|
||
ScopedFileHANDLE pipe(
|
||
CreateFile(pipe_name.c_str(),
|
||
GENERIC_READ | GENERIC_WRITE,
|
||
0,
|
||
nullptr,
|
||
OPEN_EXISTING,
|
||
SECURITY_SQOS_PRESENT | SECURITY_IDENTIFICATION,
|
||
nullptr));
|
||
if (!pipe.is_valid()) {
|
||
if (++tries == 5 || GetLastError() != ERROR_PIPE_BUSY) {
|
||
PLOG(ERROR) << "CreateFile";
|
||
return false;
|
||
}
|
||
|
||
if (!WaitNamedPipe(pipe_name.c_str(), 1000) &&
|
||
GetLastError() != ERROR_SEM_TIMEOUT) {
|
||
PLOG(ERROR) << "WaitNamedPipe";
|
||
return false;
|
||
}
|
||
|
||
continue;
|
||
}
|
||
|
||
DWORD mode = PIPE_READMODE_MESSAGE;
|
||
if (!SetNamedPipeHandleState(pipe.get(), &mode, nullptr, nullptr)) {
|
||
PLOG(ERROR) << "SetNamedPipeHandleState";
|
||
return false;
|
||
}
|
||
DWORD bytes_read = 0;
|
||
BOOL result = TransactNamedPipe(
|
||
pipe.get(),
|
||
// This is [in], but is incorrectly declared non-const.
|
||
const_cast<crashpad::ClientToServerMessage*>(&message),
|
||
sizeof(message),
|
||
response,
|
||
sizeof(*response),
|
||
&bytes_read,
|
||
nullptr);
|
||
if (!result) {
|
||
PLOG(ERROR) << "TransactNamedPipe";
|
||
return false;
|
||
}
|
||
if (bytes_read != sizeof(*response)) {
|
||
LOG(ERROR) << "TransactNamedPipe: expected " << sizeof(*response)
|
||
<< ", observed " << bytes_read;
|
||
return false;
|
||
}
|
||
return true;
|
||
}
|
||
}
|
||
|
||
} // namespace crashpad
|