Files
flameshot/external/singleapplication/singleapplication.cpp
2020-10-31 20:05:06 -05:00

286 lines
9.1 KiB
C++

// The MIT License (MIT)
//
// Copyright (c) Itay Grudev 2015 - 2020
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#include <QtCore/QByteArray>
#include <QtCore/QElapsedTimer>
#include <QtCore/QSharedMemory>
#include "singleapplication.h"
#include "singleapplication_p.h"
/**
* @brief Constructor. Checks and fires up LocalServer or closes the program
* if another instance already exists
* @param argc
* @param argv
* @param allowSecondary Whether to enable secondary instance support
* @param options Optional flags to toggle specific behaviour
* @param timeout Maximum time blocking functions are allowed during app load
*/
SingleApplication::SingleApplication(int& argc,
char* argv[],
bool allowSecondary,
Options options,
int timeout)
: app_t(argc, argv)
, d_ptr(new SingleApplicationPrivate(this))
{
Q_D(SingleApplication);
#if defined(Q_OS_ANDROID) || defined(Q_OS_IOS)
// On Android and iOS since the library is not supported fallback to
// standard QApplication behaviour by simply returning at this point.
qWarning()
<< "SingleApplication is not supported on Android and iOS systems.";
return;
#endif
// Store the current mode of the program
d->options = options;
// Generating an application ID used for identifying the shared memory
// block and QLocalServer
d->genBlockServerName();
// To mitigate QSharedMemory issues with large amount of processes
// attempting to attach at the same time
d->randomSleep();
#ifdef Q_OS_UNIX
// By explicitly attaching it and then deleting it we make sure that the
// memory is deleted even after the process has crashed on Unix.
d->memory = new QSharedMemory(d->blockServerName);
d->memory->attach();
delete d->memory;
#endif
// Guarantee thread safe behaviour with a shared memory block.
d->memory = new QSharedMemory(d->blockServerName);
// Create a shared memory block
if (d->memory->create(sizeof(InstancesInfo))) {
// Initialize the shared memory block
if (!d->memory->lock()) {
qCritical()
<< "SingleApplication: Unable to lock memory block after create.";
abortSafely();
}
d->initializeMemoryBlock();
} else {
if (d->memory->error() == QSharedMemory::AlreadyExists) {
// Attempt to attach to the memory segment
if (!d->memory->attach()) {
qCritical() << "SingleApplication: Unable to attach to shared "
"memory block.";
abortSafely();
}
if (!d->memory->lock()) {
qCritical() << "SingleApplication: Unable to lock memory block "
"after attach.";
abortSafely();
}
} else {
qCritical() << "SingleApplication: Unable to create block.";
abortSafely();
}
}
auto* inst = static_cast<InstancesInfo*>(d->memory->data());
QElapsedTimer time;
time.start();
// Make sure the shared memory block is initialised and in consistent state
while (true) {
// If the shared memory block's checksum is valid continue
if (d->blockChecksum() == inst->checksum)
break;
// If more than 5s have elapsed, assume the primary instance crashed and
// assume it's position
if (time.elapsed() > 5000) {
qWarning() << "SingleApplication: Shared memory block has been in "
"an inconsistent state from more than 5s. Assuming "
"primary instance failure.";
d->initializeMemoryBlock();
}
// Otherwise wait for a random period and try again. The random sleep
// here limits the probability of a collision between two racing apps
// and allows the app to initialise faster
if (!d->memory->unlock()) {
qDebug()
<< "SingleApplication: Unable to unlock memory for random wait.";
qDebug() << d->memory->errorString();
}
d->randomSleep();
if (!d->memory->lock()) {
qCritical()
<< "SingleApplication: Unable to lock memory after random wait.";
abortSafely();
}
}
if (inst->primary == false) {
d->startPrimary();
if (!d->memory->unlock()) {
qDebug() << "SingleApplication: Unable to unlock memory after "
"primary start.";
qDebug() << d->memory->errorString();
}
return;
}
// Check if another instance can be started
if (allowSecondary) {
d->startSecondary();
if (d->options & Mode::SecondaryNotification) {
d->connectToPrimary(timeout,
SingleApplicationPrivate::SecondaryInstance);
}
if (!d->memory->unlock()) {
qDebug() << "SingleApplication: Unable to unlock memory after "
"secondary start.";
qDebug() << d->memory->errorString();
}
return;
}
if (!d->memory->unlock()) {
qDebug()
<< "SingleApplication: Unable to unlock memory at end of execution.";
qDebug() << d->memory->errorString();
}
d->connectToPrimary(timeout, SingleApplicationPrivate::NewInstance);
delete d;
::exit(EXIT_SUCCESS);
}
SingleApplication::~SingleApplication()
{
Q_D(SingleApplication);
delete d;
}
/**
* Checks if the current application instance is primary.
* @return Returns true if the instance is primary, false otherwise.
*/
bool SingleApplication::isPrimary()
{
Q_D(SingleApplication);
return d->server != nullptr;
}
/**
* Checks if the current application instance is secondary.
* @return Returns true if the instance is secondary, false otherwise.
*/
bool SingleApplication::isSecondary()
{
Q_D(SingleApplication);
return d->server == nullptr;
}
/**
* Allows you to identify an instance by returning unique consecutive instance
* ids. It is reset when the first (primary) instance of your app starts and
* only incremented afterwards.
* @return Returns a unique instance id.
*/
quint32 SingleApplication::instanceId()
{
Q_D(SingleApplication);
return d->instanceNumber;
}
/**
* Returns the OS PID (Process Identifier) of the process running the primary
* instance. Especially useful when SingleApplication is coupled with OS.
* specific APIs.
* @return Returns the primary instance PID.
*/
qint64 SingleApplication::primaryPid()
{
Q_D(SingleApplication);
return d->primaryPid();
}
/**
* Returns the username the primary instance is running as.
* @return Returns the username the primary instance is running as.
*/
QString SingleApplication::primaryUser()
{
Q_D(SingleApplication);
return d->primaryUser();
}
/**
* Returns the username the current instance is running as.
* @return Returns the username the current instance is running as.
*/
QString SingleApplication::currentUser()
{
Q_D(SingleApplication);
return d->getUsername();
}
/**
* Sends message to the Primary Instance.
* @param message The message to send.
* @param timeout the maximum timeout in milliseconds for blocking functions.
* @return true if the message was sent successfuly, false otherwise.
*/
bool SingleApplication::sendMessage(const QByteArray& message, int timeout)
{
Q_D(SingleApplication);
// Nobody to connect to
if (isPrimary())
return false;
// Make sure the socket is connected
if (!d->connectToPrimary(timeout, SingleApplicationPrivate::Reconnect))
return false;
d->socket->write(message);
bool dataWritten = d->socket->waitForBytesWritten(timeout);
d->socket->flush();
return dataWritten;
}
/**
* Cleans up the shared memory block and exits with a failure.
* This function halts program execution.
*/
void SingleApplication::abortSafely()
{
Q_D(SingleApplication);
qCritical() << "SingleApplication: " << d->memory->error()
<< d->memory->errorString();
delete d;
::exit(EXIT_FAILURE);
}