Avoid potential rounding errors

src/modules/partition/CreatePartitionDialog.cpp

@@ -20,6 +20,7 @@
 
 #include <PartitionInfo.h>
 #include <ui_CreatePartitionDialog.h>
+#include <utils/Logger.h>
 
 // CalaPM
 #include <core/device.h>
@@ -93,19 +94,33 @@ CreatePartitionDialog::createPartitionInfo()
                  );
     }
 
-    // FIXME: Check rounding errors here
-    qint64 last = m_minSector + qint64( m_ui->sizeSpinBox->value() ) * 1024 * 1024 / m_device->logicalSectorSize();
+    qint64 lastSector;
+    int mbSize = m_ui->sizeSpinBox->value();
+    if ( mbSize == m_ui->sizeSpinBox->maximum() ) {
+        // If we are at the maximum value, select the last sector to avoid
+        // potential rounding errors which could leave a few sectors at the end
+        // unused
+        lastSector = m_maxSector;
+    } else {
+        lastSector = m_minSector + qint64( mbSize ) * 1024 * 1024 / m_device->logicalSectorSize();
+        Q_ASSERT( lastSector <= m_maxSector );
+        if ( lastSector > m_maxSector )
+        {
+            cDebug() << "lastSector (" << lastSector << ") > m_maxSector (" << m_maxSector << "). This should not happen!";
+            lastSector = m_maxSector;
+        }
+    }
 
     FileSystem::Type type = m_role.has( PartitionRole::Extended )
                             ? FileSystem::Extended
                             : FileSystem::typeForName( m_ui->fsComboBox->currentText() );
-    FileSystem* fs = FileSystemFactory::create( type, m_minSector, last );
+    FileSystem* fs = FileSystemFactory::create( type, m_minSector, lastSector );
 
     auto partition = new Partition(
         m_parent,
         *m_device,
         m_role,
-        fs, m_minSector, last,
+        fs, m_minSector, lastSector,
         QString() /* path */,
         PartitionTable::FlagNone /* availableFlags */,
         QString() /* mountPoint */,