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, 5 insertions, 1 deletions

diff --git a/src/launch-appliance.c b/src/launch-appliance.c
index 531faefd..378f1211 100644
--- a/src/launch-appliance.c
+++ b/src/launch-appliance.c
@@ -908,6 +908,8 @@ qemu_drive_param (guestfs_h *g, const struct drive *drv, size_t index)
     len += strlen (drv->iface);
   if (drv->format)
     len += strlen (drv->format);
+  if (drv->disk_label)
+    len += strlen (drv->disk_label);
 
   r = safe_malloc (g, len);
 
@@ -930,11 +932,13 @@ qemu_drive_param (guestfs_h *g, const struct drive *drv, size_t index)
   else
     iface = "virtio";
 
-  snprintf (&r[i], len-i, "%s%s%s%s,id=hd%zu,if=%s",
+  snprintf (&r[i], len-i, "%s%s%s%s%s%s,id=hd%zu,if=%s",
             drv->readonly ? ",snapshot=on" : "",
             drv->use_cache_none ? ",cache=none" : "",
             drv->format ? ",format=" : "",
             drv->format ? drv->format : "",
+            drv->disk_label ? ",serial=" : "",
+            drv->disk_label ? drv->disk_label : "",
             index,
             iface);