disk: implement Sizeable interface for PartitionTable and Partition

In our model a partition table has a size to represent the disk size.
Also each individual partition has a size, so they both implement the
Sizeable interface.

Co-Authored-By: Achilleas Koutsou <achilleas@koutsou.net>

internal/disk/partition.go

@@ -22,16 +22,6 @@ func (p *Partition) IsContainer() bool {
 	return true
 }
 
-// Ensure the partition has at least the given size. Will do nothing
-// if the partition is already larger. Returns if the size changed.
-func (p *Partition) EnsureSize(s uint64) bool {
-	if s > p.Size {
-		p.Size = s
-		return true
-	}
-	return false
-}
-
 // Converts Partition to osbuild.QEMUPartition that encodes the same partition.
 func (p *Partition) QEMUPartition() osbuild.QEMUPartition {
 	var fs *osbuild.QEMUFilesystem
@@ -62,3 +52,17 @@ func (p *Partition) GetChild(n uint) Entity {
 	}
 	return p.Filesystem
 }
+
+func (p *Partition) GetSize() uint64 {
+	return p.Size
+}
+
+// Ensure the partition has at least the given size. Will do nothing
+// if the partition is already larger. Returns if the size changed.
+func (p *Partition) EnsureSize(s uint64) bool {
+	if s > p.Size {
+		p.Size = s
+		return true
+	}
+	return false
+}

internal/disk/partition_table.go

@@ -313,6 +313,18 @@ func (pt *PartitionTable) GetChild(n uint) Entity {
 	return &pt.Partitions[n]
 }
 
+func (pt *PartitionTable) GetSize() uint64 {
+	return pt.Size
+}
+
+func (pt *PartitionTable) EnsureSize(s uint64) bool {
+	if s > pt.Size {
+		pt.Size = s
+		return true
+	}
+	return false
+}
+
 // Dynamically calculate and update the start point for each of the existing
 // partitions. Adjusts the overall size of image to either the supplied
 // value in `size` or to the sum of all partitions if that is lager.