actions/image-partition: check label length in verify stage

[vigneshraman]

The partition name (label) can be up to 11 characters long for vfat
and 16 characters long for ext3/4.

When partition name length is longer than 11 characters for vfat,
it fails with below message,
==== image-partition ====
cmdline: [mkfs.vfat -F32 -n efi456789012 /dev/vda1]
Formatting partition 1 | mkfs.vfat: Label can be no longer than 11 characters
Formatting partition 1 | mkfs.fat 4.2 (2021-01-31)
Action image-partition failed at stage Run, error: exit status 1

When partition name length is longer than 16 characters for ext2/3/4,
it shows the below warning message,
cmdline: [mkfs.ext4 -L root567890123456789 /dev/vda2]
Formatting partition 2 | Warning: label too long; will be truncated to 'root567890123456'

In case the partition name is longer than 11 for vfat, name is truncated
to 11 characters and a warning message is reported. In case of ext3/4,
it is truncated to 16 characters.

Originally-by: Christopher Obbard [email protected]
Signed-off-by: Vignesh Raman [email protected]

[obbardc]

rather than exiting, would it be better to trim the label and report a warning?
also, the docs will probably need to be changed.

[vigneshraman]

rather than exiting, would it be better to trim the label and report a warning?

@obbardc, yes it would be better to trim and report warning in case of vfat. For ext3/4, the label will be truncated to 16 characters by mkfs.ext4 and a warning is reported. So we can ignore ext3/4 case ?

also, the docs will probably need to be changed.

Sure, will check this. Thanks.

[obbardc]

you shouldn't check that here, you should check it after: for idx, _ := range i.Partitions {

you should probably also determine the label there, something like (untested):

for idx, _ := range i.Partitions {
		if p.Name == "" {
			return fmt.Errorf("Partition without a name")
		}

		// moved this code from the Run() function...
		if p.PartitionType == "gpt" {
			if p.PartLabel == "" {
				p.PartLabel = p.Name
			}

			var maxLength int = 0
			switch p.FS {
				case "vfat":
					maxLength = 11
				case "ext2":
					maxLength = 16
				case "ext3":
					maxLength = 16
			}
			if maxLength > 0 {
					truncated := p.PartLabel[0:maxLength]
					log.Printf("Warning: partition label for %s '%s' is too long; truncated to '%s'", p.Name, p.PartLabel, truncated)
					p.PartLabel = truncated
			}
		}

		// check for duplicate partition names
		for j := idx + 1; j < len(i.Partitions); j++ {
			if i.Partitions[j].Name == p.Name {
				return fmt.Errorf("Partition %s already exists", p.Name)
			}
		}
}

[vigneshraman]

@obbardc, this was added here since we need to check both m.Partition and p.Name. Can we do the above check before if m.Partition == p.Name check ? Do we need to truncate m.Partition also ?

[obbardc]

spurious change

[obbardc]

also, can we have a look at the maximum lengths for the other filesystems ?

[vigneshraman]

Sure. Will check for btrfs, xfs, reiserfs, jfs.

[obbardc]

Suggested change

	long for ext2/3/4. Name should be same as partition name in mount points.
	long for ext2/3/4. Any longer labels will be automatically truncated.

also; the length should probably be moved to the partlabel documentation

[obbardc]

Suggested change

	unique. The partition name can be up to 11 characters long for vfat and 16 characters
	unique. The partition label can be up to 11 characters long for vfat and 16 characters

[obbardc]

you can also remove duplicate code in Run():

		if p.PartLabel == "" {
			p.PartLabel = p.Name
		}

[vigneshraman]

Closing this PR. New proposed changes are in #271