qgsrunprocess.cpp

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/***************************************************************************
                          qgsrunprocess.cpp
 
 A class that runs an external program
 
                             -------------------
    begin                : Jan 2005
    copyright            : (C) 2005 by Gavin Macaulay
    email                : gavin at macaulay dot co dot nz
 ***************************************************************************/
 
/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsrunprocess.h"
 
#include "qgis.h"
#include "qgsapplication.h"
#include "qgsfeedback.h"
#include "qgslogger.h"
#include "qgsmessageoutput.h"
 
#include <QApplication>
#include <QMessageBox>
#include <QProcess>
#include <QTextCodec>
 
#include "moc_qgsrunprocess.cpp"
 
#if QT_CONFIG( process )
QgsRunProcess::QgsRunProcess( const QString &action, bool capture )
 
{
  // Make up a string from the command and arguments that we'll use
  // for display purposes
  QgsDebugMsgLevel( "Running command: " + action, 2 );
 
  mCommand = action;
 
  QStringList arguments = QProcess::splitCommand( action );
  const QString command = arguments.value( 0 );
  if ( !arguments.isEmpty() )
    arguments.removeFirst();
 
  mProcess = std::make_unique<QProcess>();
 
  if ( capture )
  {
    connect( mProcess.get(), &QProcess::errorOccurred, this, &QgsRunProcess::processError );
    connect( mProcess.get(), &QProcess::readyReadStandardOutput, this, &QgsRunProcess::stdoutAvailable );
    connect( mProcess.get(), &QProcess::readyReadStandardError, this, &QgsRunProcess::stderrAvailable );
    // We only care if the process has finished if we are capturing
    // the output from the process, hence this connect() call is
    // inside the capture if() statement.
    connect( mProcess.get(), static_cast< void ( QProcess::* )( int, QProcess::ExitStatus ) >( &QProcess::finished ), this, &QgsRunProcess::processExit );
 
    // Use QgsMessageOutput for displaying output to user
    // It will delete itself when the dialog box is closed.
    mOutput = QgsMessageOutput::createMessageOutput();
    mOutput->setTitle( action );
    mOutput->setMessage( tr( "<b>Starting %1…</b>" ).arg( action ), Qgis::StringFormat::Html );
    mOutput->showMessage( false ); // non-blocking
 
    // get notification of delete if it's derived from QObject
    QObject *mOutputObj = dynamic_cast<QObject *>( mOutput );
    if ( mOutputObj )
    {
      connect( mOutputObj, &QObject::destroyed, this, &QgsRunProcess::dialogGone );
    }
 
    // start the process!
    mProcess->start( command, arguments );
  }
  else
  {
    if ( !QProcess::startDetached( command, arguments ) ) // let the program run by itself
    {
      QMessageBox::critical( nullptr, tr( "Action" ), tr( "Unable to run command\n%1" ).arg( action ), QMessageBox::Ok, Qt::NoButton );
    }
    // We're not capturing the output from the process, so we don't
    // need to exist anymore.
    die();
  }
}
 
QgsRunProcess::~QgsRunProcess()
{}
 
void QgsRunProcess::die()
{
  // safe way to do "delete this" for QObjects
  deleteLater();
}
 
void QgsRunProcess::stdoutAvailable()
{
  const QByteArray bytes( mProcess->readAllStandardOutput() );
  QTextCodec *codec = QTextCodec::codecForLocale();
  const QString line( codec->toUnicode( bytes ) );
 
  // Add the new output to the dialog box
  mOutput->appendMessage( line );
}
 
void QgsRunProcess::stderrAvailable()
{
  const QByteArray bytes( mProcess->readAllStandardOutput() );
  QTextCodec *codec = QTextCodec::codecForLocale();
  const QString line( codec->toUnicode( bytes ) );
 
  // Add the new output to the dialog box, but color it red
  mOutput->appendMessage( "<font color=red>" + line + "</font>" );
}
 
void QgsRunProcess::processExit( int, QProcess::ExitStatus )
{
  // Because we catch the dialog box going (the dialogGone()
  // function), and delete this instance, control will only pass to
  // this function if the dialog box still exists when the process
  // exits, so it's always safe to use the pointer to the dialog box
  // (unless it was never created in the first case, which is what the
  // test against 0 is for).
 
  if ( mOutput )
  {
    mOutput->appendMessage( "<b>" + tr( "Done" ) + "</b>" );
  }
 
  // Since the dialog box takes care of deleting itself, and the
  // process has gone, there's no need for this instance to stay
  // around, so we disappear too.
  die();
}
 
void QgsRunProcess::dialogGone()
{
  // The dialog has gone, so the user is no longer interested in the
  // output from the process. Since the process will run happily
  // without the QProcess object, this instance and its data can then
  // go too, but disconnect the signals to prevent further functions in this
  // class being called after it has been deleted (Qt seems not to be
  // disconnecting them itself)
 
  mOutput = nullptr;
 
  disconnect( mProcess.get(), &QProcess::errorOccurred, this, &QgsRunProcess::processError );
  disconnect( mProcess.get(), &QProcess::readyReadStandardOutput, this, &QgsRunProcess::stdoutAvailable );
  disconnect( mProcess.get(), &QProcess::readyReadStandardError, this, &QgsRunProcess::stderrAvailable );
  disconnect( mProcess.get(), static_cast< void ( QProcess::* )( int, QProcess::ExitStatus ) >( &QProcess::finished ), this, &QgsRunProcess::processExit );
 
  die();
}
 
void QgsRunProcess::processError( QProcess::ProcessError err )
{
  if ( err == QProcess::FailedToStart )
  {
    QgsMessageOutput *output = mOutput ? mOutput : QgsMessageOutput::createMessageOutput();
    output->setMessage( tr( "Unable to run command %1" ).arg( mCommand ), Qgis::StringFormat::PlainText );
    // Didn't work, so no need to hang around
    die();
  }
  else
  {
    QgsDebugError( "Got error: " + QString( "%d" ).arg( err ) );
  }
}
 
QStringList QgsRunProcess::splitCommand( const QString &command )
{
  return QProcess::splitCommand( command );
}
#else
QgsRunProcess::QgsRunProcess( const QString &action, bool )
{
  Q_UNUSED( action )
  QgsDebugError( "Skipping command: " + action );
}
 
QgsRunProcess::~QgsRunProcess()
{}
 
QStringList QgsRunProcess::splitCommand( const QString & )
{
  return QStringList();
}
#endif
 
 
//
// QgsBlockingProcess
//
 
#if QT_CONFIG( process )
QgsBlockingProcess::QgsBlockingProcess( const QString &process, const QStringList &arguments )
  : QObject()
  , mProcess( process )
  , mArguments( arguments )
{}
 
int QgsBlockingProcess::run( QgsFeedback *feedback )
{
  const bool requestMadeFromMainThread = QThread::currentThread() == QCoreApplication::instance()->thread();
 
  int result = 0;
  QProcess::ExitStatus exitStatus = QProcess::NormalExit;
  QProcess::ProcessError error = QProcess::UnknownError;
 
  const std::function<void()> runFunction = [this, &result, &exitStatus, &error, feedback]() {
    // this function will always be run in worker threads -- either the blocking call is being made in a worker thread,
    // or the blocking call has been made from the main thread and we've fired up a new thread for this function
    Q_ASSERT( QThread::currentThread() != QgsApplication::instance()->thread() );
 
    QProcess p;
    const QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
    p.setProcessEnvironment( env );
 
    QEventLoop loop;
    // connecting to aboutToQuit avoids an on-going process to remain stalled
    // when QThreadPool::globalInstance()->waitForDone()
    // is called at process termination
    connect( qApp, &QCoreApplication::aboutToQuit, &loop, &QEventLoop::quit, Qt::DirectConnection );
 
    if ( feedback )
      QObject::connect( feedback, &QgsFeedback::canceled, &p, [&p] {
#ifdef Q_OS_WIN
        // From the qt docs:
        // "Console applications on Windows that do not run an event loop, or whose
        // event loop does not handle the WM_CLOSE message, can only be terminated by calling kill()."
        p.kill();
#else
      p.terminate();
#endif
      } );
    connect(
      &p,
      qOverload< int, QProcess::ExitStatus >( &QProcess::finished ),
      this,
      [&loop, &result, &exitStatus]( int res, QProcess::ExitStatus st ) {
        result = res;
        exitStatus = st;
        loop.quit();
      },
      Qt::DirectConnection
    );
 
    connect( &p, &QProcess::readyReadStandardOutput, &p, [&p, this] {
      const QByteArray ba = p.readAllStandardOutput();
      mStdoutHandler( ba );
    } );
    connect( &p, &QProcess::readyReadStandardError, &p, [&p, this] {
      const QByteArray ba = p.readAllStandardError();
      mStderrHandler( ba );
    } );
    p.start( mProcess, mArguments, QProcess::Unbuffered | QProcess::ReadWrite );
    if ( !p.waitForStarted() )
    {
      result = 1;
      exitStatus = QProcess::NormalExit;
      error = p.error();
    }
    else
    {
      loop.exec();
    }
 
    mStdoutHandler( p.readAllStandardOutput() );
    mStderrHandler( p.readAllStandardError() );
  };
 
  if ( requestMadeFromMainThread )
  {
    auto processThread = std::make_unique<ProcessThread>( runFunction );
    processThread->start();
    // wait for thread to gracefully exit
    processThread->wait();
  }
  else
  {
    runFunction();
  }
 
  mExitStatus = exitStatus;
  mProcessError = error;
  return result;
}
 
QProcess::ExitStatus QgsBlockingProcess::exitStatus() const
{
  return mExitStatus;
};
 
QProcess::ProcessError QgsBlockingProcess::processError() const
{
  return mProcessError;
};
#endif // QT_CONFIG(process)