[machineid] Use entropy service

- Most of the code was error-checking, just replace the open-read
   with a call to the service instead.
 - It's not an error if /dev/urandom doesn't exist in the source system
   (there may be other good random sources, and otherwise we have the
   low-quality random fallback).

src/modules/machineid/Workers.cpp

@@ -3,7 +3,7 @@
  *   Copyright 2014, Kevin Kofler <kevin.kofler@chello.at>
  *   Copyright 2016, Philip Müller <philm@manjaro.org>
  *   Copyright 2017, Alf Gaida <agaida@siduction.org>
- *   Copyright 2019, Adriaan de Groot <groot@kde.org>
+ *   Copyright 2019-2020, Adriaan de Groot <groot@kde.org>
  *
  *   Calamares is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 #include "Workers.h"
 
 #include "utils/CalamaresUtilsSystem.h"
+#include "utils/Entropy.h"
 #include "utils/Logger.h"
 
 #include <QFile>
@@ -99,12 +100,6 @@ getUrandomPoolSize()
 Calamares::JobResult
 createNewEntropy( int poolSize, const QString& rootMountPoint, const QString& fileName )
 {
-    QFile urandom( "/dev/urandom" );
-    if ( urandom.exists() && urandom.open( QIODevice::ReadOnly ) )
-    {
-        QByteArray data = urandom.read( poolSize );
-        urandom.close();
-
     QFile entropyFile( rootMountPoint + fileName );
     if ( entropyFile.exists() )
     {
@@ -117,6 +112,9 @@ createNewEntropy( int poolSize, const QString& rootMountPoint, const QString& fi
             QObject::tr( "File not found" ),
             QObject::tr( "Could not create new random file <pre>%1</pre>." ).arg( fileName ) );
     }
+
+    QByteArray data;
+    CalamaresUtils::EntropySource source = CalamaresUtils::getEntropy( poolSize, data );
     entropyFile.write( data );
     entropyFile.close();
     if ( entropyFile.size() < data.length() )
@@ -127,11 +125,11 @@ createNewEntropy( int poolSize, const QString& rootMountPoint, const QString& fi
     {
         cWarning() << "Entropy data is" << data.length() << "bytes, rather than poolSize" << poolSize;
     }
-        return Calamares::JobResult::ok();
+    if ( source != CalamaresUtils::EntropySource::URandom )
+    {
+        cWarning() << "Entropy data for pool is low-quality.";
     }
-    return Calamares::JobResult::error(
-        QObject::tr( "File not found" ),
-        QObject::tr( "Could not read random file <pre>%1</pre>." ).arg( QStringLiteral( "/dev/urandom" ) ) );
+    return Calamares::JobResult::ok();
 }