launch: Add add_drive 'label' option.

New API: list-disk-labels

Allow the user to pass an optional disk label when adding a drive.

This is passed through to qemu / libvirt using the disk serial field,
and from there to the appliance which exposes it through udev,
creating a special alias of the device /dev/disk/guestfs/<label>.
Partitions are named /dev/disk/guestfs/<label><partnum>.

virtio-blk and virtio-scsi limit the serial field to 20 bytes.  We
further limit the name to maximum 20 ASCII characters in [a-zA-Z].

list-devices and list-partitions are not changed: these calls still
return raw block device names.  However a new call, list-disk-labels,
returns a hash table allowing callers to map between disk labels, and
block device and partition names.

This commit also includes a test.

1 files changed, 27 insertions, 1 deletions

diff --git a/generator/actions.ml b/generator/actions.ml
index 713c7162..25d28098 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -1184,7 +1184,7 @@ not all belong to a single logical operating system
 
   { defaults with
     name = "add_drive";
-    style = RErr, [String "filename"], [OBool "readonly"; OString "format"; OString "iface"; OString "name"];
+    style = RErr, [String "filename"], [OBool "readonly"; OString "format"; OString "iface"; OString "name"; OString "label"];
     once_had_no_optargs = true;
     fish_alias = ["add"]; config_only = true;
     shortdesc = "add an image to examine or modify";
@@ -1238,6 +1238,15 @@ The name the drive had in the original guest, e.g. C</dev/sdb>.
 This is used as a hint to the guest inspection process if
 it is available.
 
+=item C<label>
+
+Give the disk a label.  The label should be a unique, short
+string using I<only> ASCII characters C<[a-zA-Z]>.
+As well as its usual name in the API (such as C</dev/sda>),
+the drive will also be named C</dev/disk/guestfs/I<label>>.
+
+See L<guestfs(3)/DISK LABELS>.
+
 =back" };
 
   { defaults with
@@ -9925,6 +9934,23 @@ on C<device>.  The optional C<blockscount> is the size of the
 filesystem in blocks.  If omitted it defaults to the size of
 C<device>." (* XXX document optional args properly *) };
 
+  { defaults with
+    name = "list_disk_labels";
+    style = RHashtable "labels", [], [];
+    proc_nr = Some 369;
+    tests = [];
+    shortdesc = "mapping of disk labels to devices";
+    longdesc = "\
+If you add drives using the optional C<label> parameter
+of C<guestfs_add_drive_opts>, you can use this call to
+map between disk labels, and raw block device and partition
+names (like C</dev/sda> and C</dev/sda1>).
+
+This returns a hashtable, where keys are the disk labels
+(I<without> the C</dev/disk/guestfs> prefix), and the values
+are the full raw block device and partition names
+(eg. C</dev/sda> and C</dev/sda1>)." };
+
 ]
 
 (* Non-API meta-commands available only in guestfish.