disk: honour maximum number of partitions

Return an error if the maximum numbers of partitions has been
reached and thus creating further partitions would result in
errors.
Currently we limit MBR partition types to 4 as we dont support
logical partitions and GPT layouts to 128. According to the
UEFI specificatio (2.8) a minimum of 16384 bytes are reserved
for the partition entries array. Each entry is 128 bytes wide
thus resulting in at least 128 entries; we choose this to be
the maximum as well for now.

internal/disk/customizations.go

@@ -42,7 +42,10 @@ func CreatePartitionTable(
 		if part != nil {
 			part.EnsureSize(sectors)
 		} else {
-			table.CreateFilesystem(m.Mountpoint, sectors)
+			err := table.CreateFilesystem(m.Mountpoint, sectors)
+			if err != nil {
+				return PartitionTable{}, err
+			}
 		}
 	}
 

internal/disk/disk.go

@@ -7,6 +7,7 @@ package disk
 import (
 	"encoding/hex"
 	"errors"
+	"fmt"
 	"io"
 	"math/rand"
 	"sort"
@@ -279,7 +280,7 @@ func (pt *PartitionTable) BootFilesystem() *Filesystem {
 
 // Create a new filesystem within the partition table at the given mountpoint
 // with the given minimum size in sectors.
-func (pt *PartitionTable) CreateFilesystem(mountpoint string, size uint64) {
+func (pt *PartitionTable) CreateFilesystem(mountpoint string, size uint64) error {
 	filesystem := Filesystem{
 		Type:         "xfs",
 		Mountpoint:   mountpoint,
@@ -293,11 +294,23 @@ func (pt *PartitionTable) CreateFilesystem(mountpoint string, size uint64) {
 		Filesystem: &filesystem,
 	}
 
+	n := len(pt.Partitions)
+	var maxNo int
+
 	if pt.Type == "gpt" {
 		partition.Type = FilesystemDataGUID
+		maxNo = 128
+	} else {
+		maxNo = 4
+	}
+
+	if n == maxNo {
+		return fmt.Errorf("maximum number of partitions reached (%d)", maxNo)
 	}
 
 	pt.Partitions = append(pt.Partitions, partition)
+
+	return nil
 }
 
 // Generate all needed UUIDs for all the partiton and filesystems

internal/distro/rhel85/distro_test.go

@@ -684,10 +684,13 @@ func TestDistro_MountpointsWithArbitraryDepthAllowed(t *testing.T) {
 			imgType, _ := arch.GetImageType(imgTypeName)
 			testPackageSpecSets := distro_test_common.GetTestingPackageSpecSets("kernel", arch.Name(), imgType.PayloadPackageSets())
 			_, err := imgType.Manifest(bp.Customizations, distro.ImageOptions{}, nil, testPackageSpecSets, 0)
-			if strings.HasPrefix(imgTypeName, "edge-") {
+			layout := imgType.PartitionType()
+			if layout == "" || strings.HasPrefix(imgTypeName, "edge-") {
 				continue
-			} else {
+			} else if layout == "gpt" {
 				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, "maximum number of partitions reached (4)")
 			}
 		}
 	}

internal/distro/rhel86/distro_test.go

@@ -693,10 +693,13 @@ func TestDistro_MountpointsWithArbitraryDepthAllowed(t *testing.T) {
 			imgType, _ := arch.GetImageType(imgTypeName)
 			testPackageSpecSets := distro_test_common.GetTestingPackageSpecSets("kernel", arch.Name(), imgType.PayloadPackageSets())
 			_, err := imgType.Manifest(bp.Customizations, distro.ImageOptions{}, nil, testPackageSpecSets, 0)
-			if strings.HasPrefix(imgTypeName, "edge-") {
+			layout := imgType.PartitionType()
+			if layout == "" || strings.HasPrefix(imgTypeName, "edge-") {
 				continue
-			} else {
+			} else if layout == "gpt" {
 				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, "maximum number of partitions reached (4)")
 			}
 		}
 	}

internal/distro/rhel90/distro_test.go

@@ -654,8 +654,12 @@ func TestDistro_CustomFileSystemSubDirectories(t *testing.T) {
 			imgType, _ := arch.GetImageType(imgTypeName)
 			testPackageSpecSets := distro_test_common.GetTestingPackageSpecSets("kernel", arch.Name(), imgType.PayloadPackageSets())
 			_, err := imgType.Manifest(bp.Customizations, distro.ImageOptions{}, nil, testPackageSpecSets, 0)
+			layout := imgType.PartitionType()
 			if strings.HasPrefix(imgTypeName, "edge-") {
 				continue
+			} else if layout == "dos" && arch.Name() == distro.Ppc64leArchName {
+				// PPC64LE uses mbr and has 3 partitions defined in the base layout
+				assert.EqualError(t, err, "maximum number of partitions reached (4)")
 			} else {
 				assert.NoError(t, err)
 			}
@@ -693,10 +697,13 @@ func TestDistro_MountpointsWithArbitraryDepthAllowed(t *testing.T) {
 			imgType, _ := arch.GetImageType(imgTypeName)
 			testPackageSpecSets := distro_test_common.GetTestingPackageSpecSets("kernel", arch.Name(), imgType.PayloadPackageSets())
 			_, err := imgType.Manifest(bp.Customizations, distro.ImageOptions{}, nil, testPackageSpecSets, 0)
-			if strings.HasPrefix(imgTypeName, "edge-") {
+			layout := imgType.PartitionType()
+			if layout == "" || strings.HasPrefix(imgTypeName, "edge-") {
 				continue
-			} else {
+			} else if layout == "gpt" {
 				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, "maximum number of partitions reached (4)")
 			}
 		}
 	}

internal/distro/rhel90beta/distro_test.go

@@ -686,10 +686,13 @@ func TestDistro_MountpointsWithArbitraryDepthAllowed(t *testing.T) {
 			imgType, _ := arch.GetImageType(imgTypeName)
 			testPackageSpecSets := distro_test_common.GetTestingPackageSpecSets("kernel", arch.Name(), imgType.PayloadPackageSets())
 			_, err := imgType.Manifest(bp.Customizations, distro.ImageOptions{}, nil, testPackageSpecSets, 0)
-			if strings.HasPrefix(imgTypeName, "edge-") {
+			layout := imgType.PartitionType()
+			if layout == "" || strings.HasPrefix(imgTypeName, "edge-") {
 				continue
-			} else {
+			} else if layout == "gpt" {
 				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, "maximum number of partitions reached (4)")
 			}
 		}
 	}