refactor: Get process IDs by iterating /proc. Improve readability in JsonConnection option handling. (#843)

Co-authored-by: brindosch <edeltraud70@gmx.de>

src/hyperiond/detectProcess.h

@@ -1,8 +1,11 @@
 #pragma once
 
-#include <QString>
-#include <QProcess>
 #include <QByteArray>
+#include <QDir>
+#include <QFile>
+#include <QRegExp>
+#include <QString>
+#include <QTextStream>
 
 #ifdef WIN32
 // psapi.h requires windows.h to be included
@@ -12,7 +15,6 @@
 
 unsigned int getProcessIdsByProcessName(const char *processName, QStringList &listOfPids)
 {
-
 	// Clear content of returned list of PIDS
 	listOfPids.clear();
 
@@ -57,33 +59,36 @@ unsigned int getProcessIdsByProcessName(const char *processName, QStringList &li
 		}
 	}
 
-	return listOfPids.count();
-
 #else
 
-	// Run pgrep, which looks through the currently running processses and lists the process IDs
-	// which match the selection criteria to stdout.
-	QProcess process;
-	process.start("pgrep", QStringList() << processName);
-	process.waitForReadyRead();
+	QDir dir("/proc");
+	dir.setFilter(QDir::Dirs);
+	dir.setSorting(QDir::Name | QDir::Reversed);
 
-	QByteArray bytes = process.readAllStandardOutput();
+	for (const QString & pid : dir.entryList()) {
+		QRegExp regexp("\\d*");
+		if (!regexp.exactMatch(pid))
+		{
+			/* Not a number, can not be PID */
+			continue;
+		}
 
-	process.terminate();
-	process.waitForFinished();
-	process.kill();
+		QFile cmdline("/proc/" + pid + "/cmdline");
+		if (!cmdline.open(QFile::ReadOnly | QFile::Text))
+		{
+			/* Can not open cmdline file */
+			continue;
+		}
 
-	// Output is something like "2472\n2323" for multiple instances
-	if (bytes.isEmpty())
-		return 0;
-
-	#if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
-		listOfPids = QString(bytes).split("\n", Qt::SkipEmptyParts);
-	#else
-		listOfPids = QString(bytes).split("\n", QString::SkipEmptyParts);
-	#endif
-
-	return listOfPids.count();
+		QTextStream in(&cmdline);
+		QString command = in.readAll();
+		if (command.startsWith(processName))
+		{
+			listOfPids.push_back(pid);
+		}
+	}
 
 #endif
+
+	return listOfPids.count();
 }

src/hyperiond/main.cpp

@@ -153,7 +153,6 @@ int main(int argc, char** argv)
 	Logger::setLogLevel(Logger::WARNING);
 
 	// check if we are running already an instance
-	// TODO Do not use pgrep on linux, instead iter /proc
 	// TODO Allow one session per user
 	// http://www.qtcentre.org/threads/44489-Get-Process-ID-for-a-running-application
 	QStringList listOfPids;
@@ -196,8 +195,8 @@ int main(int argc, char** argv)
 	BooleanOption & silentOption        = parser.add<BooleanOption> ('s', "silent", "do not print any outputs");
 	BooleanOption & verboseOption       = parser.add<BooleanOption> ('v', "verbose", "Increase verbosity");
 	BooleanOption & debugOption         = parser.add<BooleanOption> ('d', "debug", "Show debug messages");
-                                          parser.add<BooleanOption> (0x0, "desktop", "show systray on desktop");
-	                                      parser.add<BooleanOption> (0x0, "service", "force hyperion to start as console service");
+					      parser.add<BooleanOption> (0x0, "desktop", "show systray on desktop");
+					      parser.add<BooleanOption> (0x0, "service", "force hyperion to start as console service");
 	Option        & exportEfxOption     = parser.add<Option>        (0x0, "export-effects", "export effects to given path");
 
 	parser.process(*qApp);

src/hyperiond/systray.cpp

@@ -88,7 +88,7 @@ void SysTray::createTrayIcon()
 		connect(efxAction, SIGNAL(triggered()), this, SLOT(setEffect()));
 		_trayIconEfxMenu->addAction(efxAction);
 	}
-	
+
 	_trayIconMenu->addAction(settingsAction);
 	_trayIconMenu->addSeparator();
 	_trayIconMenu->addAction(colorAction);
@@ -104,7 +104,7 @@ void SysTray::createTrayIcon()
 void SysTray::setColor(const QColor & color)
 {
 	std::vector<ColorRgb> rgbColor{ ColorRgb{ (uint8_t)color.red(), (uint8_t)color.green(), (uint8_t)color.blue() } };
- 
+
  	_hyperion->setColor(1 ,rgbColor, 0);
 }
 
@@ -149,7 +149,7 @@ void SysTray::settings()
 	#endif
 
 	QDesktopServices::openUrl(QUrl("http://localhost:"+QString::number(_webPort)+"/", QUrl::TolerantMode));
-	
+
 	#ifndef _WIN32
 	// restoring stdout
 	::dup2(saved_stdout, STDOUT_FILENO);