Qt4.8 m_process->waitForFinished()

m_process->waitForFinished(-1)

bool QProcess::waitForFinished ( int msecs = 30000 ) Blocks until the process has finished and the finished() signal has been emitted, or until msecs milliseconds have passed.

If msecs is -1, this function will not time out.

С уважением, ваш персональный гугл.