[Libguestfs] [PATCH 3/3] resize: Preserve GPT GUID so we don't break EFI bootloaders (RHBZ#1189284).

[Richard W.M. Jones]

When copying disks that use EFI, we created a new partition table,
randomizing the GPT GUID of the first partition.  Since EFI may store
the GUID in its NVRAM variables, this could make the guest unbootable.
---
 resize/resize.ml | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/resize/resize.ml b/resize/resize.ml
index 871c6a4..84fd6d4 100644
--- a/resize/resize.ml
+++ b/resize/resize.ml
@@ -50,6 +50,7 @@ type partition = {
   p_id : partition_id;           (* Partition (MBR/GPT) ID. *)
   p_type : partition_content;    (* Content type and content size. *)
   p_label : string option;       (* Label/name. *)
+  p_guid : string option;        (* Partition GUID (GPT only). *)
 
   (* What we're going to do: *)
   mutable p_operation : partition_operation;
@@ -93,6 +94,11 @@ let rec debug_partition p =
     (match p.p_label with
     | Some label -> label
     | None -> "(none)"
+    );
+  printf "\tGUID: %s\n"
+    (match p.p_guid with
+    | Some guid -> guid
+    | None -> "(none)"
     )
 and string_of_partition_content = function
   | ContentUnknown -> "unknown data"
@@ -479,10 +485,16 @@ read the man page virt-resize(1).
           let label =
             try Some (g#part_get_name "/dev/sda" part_num)
             with G.Error _ -> None in
+          let guid =
+            match parttype with
+            | MBR -> None
+            | GPT ->
+              try Some (g#part_get_gpt_guid "/dev/sda" part_num)
+              with G.Error _ -> None in
 
           { p_name = name; p_part = part;
             p_bootable = bootable; p_id = id; p_type = typ;
-            p_label = label;
+            p_label = label; p_guid = guid;
             p_operation = OpCopy; p_target_partnum = 0;
             p_target_start = 0L; p_target_end = 0L }
       ) parts in
@@ -1068,7 +1080,7 @@ read the man page virt-resize(1).
           p_part = { G.part_num = 0l; part_start = 0L; part_end = 0L;
                      part_size = 0L };
           p_bootable = false; p_id = No_ID; p_type = ContentUnknown;
-          p_label = None;
+          p_label = None; p_guid = None;
 
           (* Target information is meaningful. *)
           p_operation = OpIgnore;
@@ -1167,6 +1179,12 @@ read the man page virt-resize(1).
       | None -> ()
       );
 
+      (match p.p_guid with
+      | Some guid ->
+        g#part_set_gpt_guid "/dev/sdb" p.p_target_partnum guid;
+      | None -> ()
+      );
+
       match parttype, p.p_id with
       | GPT, GPT_Type gpt_type ->
         g#part_set_gpt_type "/dev/sdb" p.p_target_partnum gpt_type
-- 
2.1.0