Initialise QBtCommandLineParameters members from environment

This allows to pass options via environment variables. The variable name
is constructed from parameter name by transforming the name to upper
case and prefixing "QBT_".

src/app/options.cpp

@@ -33,7 +33,10 @@
 #include "options.h"
 
 #include <iostream>
+
+#include <QDebug>
 #include <QFileInfo>
+#include <QProcessEnvironment>
 
 #ifdef Q_OS_WIN
 #include <QMessageBox>
@@ -41,26 +44,56 @@
 
 #include "base/utils/misc.h"
 
-QBtCommandLineParameters::QBtCommandLineParameters()
+namespace
+{
+    bool isBoolEnvVarSetToTrue(const QProcessEnvironment &env, const QString &var)
+    {
+        QString val = env.value(var);
+        // we accept "1" and "true" (upper or lower cased) as boolean 'true' values
+        return (val == QLatin1String("1") || val.toUpper() == QLatin1String("TRUE"));
+    }
+
+    int readIntlEnvVar(const QProcessEnvironment &env, const QString &var, int defaultValue)
+    {
+        QString val = env.value(var);
+        if (val.isEmpty()) return defaultValue;
+        bool ok;
+        int res = val.toInt(&ok);
+        if (!ok) {
+            qDebug() << QObject::tr("Expected integer number in environment variable '%1', but got '%2'")
+                .arg(var).arg(val);
+            return defaultValue;
+        }
+        return res;
+    }
+
+    QString envVarNameForParameter(const char *parameterName)
+    {
+        return QLatin1String("QBT_") +
+               QString(QLatin1String(parameterName)).toUpper().replace(QLatin1Char('-'), QLatin1Char('_'));
+    }
+}
+
+QBtCommandLineParameters::QBtCommandLineParameters(const QProcessEnvironment &env)
     : showHelp(false)
 #ifndef Q_OS_WIN
     , showVersion(false)
 #endif
 #ifndef DISABLE_GUI
-    , noSplash(false)
+    , noSplash(isBoolEnvVarSetToTrue(env, envVarNameForParameter("no-splash")))
 #else
-    , shouldDaemonize(false)
+    , shouldDaemonize(isBoolEnvVarSetToTrue(env, envVarNameForParameter("daemon")))
 #endif
-    , webUiPort(-1)
-    , profileDir()
-    , portableMode(false)
-    , configurationName()
+    , webUiPort(readIntlEnvVar(env, envVarNameForParameter("webui-port"), -1))
+    , profileDir(env.value(envVarNameForParameter("profile")))
+    , portableMode(isBoolEnvVarSetToTrue(env, envVarNameForParameter("portable")))
+    , configurationName(env.value(envVarNameForParameter("configuration")))
 {
 }
 
 QBtCommandLineParameters parseCommandLine(const QStringList &args)
 {
-    QBtCommandLineParameters result;
+    QBtCommandLineParameters result {QProcessEnvironment::systemEnvironment()};
 
     for (int i = 1; i < args.count(); ++i) {
         const QString &arg = args[i];
@@ -189,4 +222,3 @@ void displayUsage(const QString& prgName)
     msgBox.exec();
 #endif
 }
-

src/app/options.h

@@ -38,6 +38,8 @@
 #include <QString>
 #include <QStringList>
 
+class QProcessEnvironment;
+
 struct QBtCommandLineParameters
 {
     bool showHelp;
@@ -56,7 +58,7 @@ struct QBtCommandLineParameters
     QStringList torrents;
     QString unknownParameter;
 
-    QBtCommandLineParameters();
+    QBtCommandLineParameters(const QProcessEnvironment&);
 };
 
 class CommandLineParameterError: public std::runtime_error