partition: simplify Arm code

- introduce a helper function for accessing the globalstorage value
- add consts and calculate the initial gap in a single expression

src/modules/partition/core/PartUtils.cpp

@@ -441,17 +441,16 @@ runOsprober( DeviceModel* dm )
 }
 
 bool
-isEfiSystem()
+isArmSystem()
 {
     Calamares::GlobalStorage* gs = Calamares::JobQueue::instance()->globalStorage();
-    if ( gs->contains( "armInstall" ) && gs->value( "armInstall" ).toBool() )
-    {
-        return true;
-    }
-    else
-    {
-        return QDir( "/sys/firmware/efi/efivars" ).exists();
-    }
+    return gs->contains( "armInstall" ) && gs->value( "armInstall" ).toBool() );
+}
+
+bool
+isEfiSystem()
+{
+    return isArmSystem() || QDir( "/sys/firmware/efi/efivars" ).exists();
 }
 
 bool

src/modules/partition/core/PartUtils.h

@@ -77,6 +77,11 @@ bool canBeResized( DeviceModel* dm, const QString& partitionPath, const Logger::
  */
 OsproberEntryList runOsprober( DeviceModel* dm );
 
+/**
+ * @brief Is this an ARM-based system? Set in the configuration file
+ */
+bool isArmSystem();
+
 /**
  * @brief Is this system EFI-enabled? Decides based on /sys/firmware/efi
  */

src/modules/partition/core/PartitionActions.cpp

@@ -89,22 +89,15 @@ doAutopartition( PartitionCoreModule* core, Device* dev, Choices::AutoPartitionO
 {
     Calamares::GlobalStorage* gs = Calamares::JobQueue::instance()->globalStorage();
 
-    bool isEfi = PartUtils::isEfiSystem();
+    const bool isEfi = PartUtils::isEfiSystem();
 
     // Partition sizes are expressed in MiB, should be multiples of
     // the logical sector size (usually 512B). EFI starts with 2MiB
     // empty and a EFI boot partition, while BIOS starts at
     // the 1MiB boundary (usually sector 2048).
     // ARM empty sectors are 16 MiB in size.
-    int empty_space_sizeB;
-    if ( gs->contains( "armInstall" ) && gs->value( "armInstall" ).toBool() )
-    {
-        empty_space_sizeB = 16_MiB;
-    }
-    else
-    {
-        empty_space_sizeB = isEfi ? 2_MiB : 1_MiB;
-    }
+    const int empty_space_sizeB = PartUtils::isArmSystem() ? 16_MiB : ( isEfi ? 2_MiB : 1_MiB );
+
     // Since sectors count from 0, if the space is 2048 sectors in size,
     // the first free sector has number 2048 (and there are 2048 sectors
     // before that one, numbered 0..2047).