[Libguestfs] [PATCH 3/4] v2v: win >= 8: simplify registry patching

[Roman Kagan]

It turned out (by trial and error) that for Windows >= 8 / 2012, even
though the PnP system uses names related to the original driver's .inf
file for certain entries under DriverDatabase registry subtree, this
doesn't have to hold for the storage driver to make it boot.

So use our own artificial names there and simplify the surrounding code.
This will also make sure the added entries don't confilct with those
generated by PnP proper once the driver is installed, and that the
entries are easy to look up in the eventual registry.

The name chosen to refer to the driver -- "guestor" -- is intentionally
different from the original "viostor" both to avoid collisions and to
naturally expand to other relevant drivers (e.g. "vioscsi") later on.

Tested on

Win 8 x32
Win 8 x64
Win 8.1 x32
Win 8.1 x64
Win 2012R2 x64
Win 10 x64

Signed-off-by: Roman Kagan <rkagan at virtuozzo.com>
---
 v2v/windows_virtio.ml | 51 +++++++++++----------------------------------------
 1 file changed, 11 insertions(+), 40 deletions(-)

diff --git a/v2v/windows_virtio.ml b/v2v/windows_virtio.ml
index 738fa11..c76a677 100644
--- a/v2v/windows_virtio.ml
+++ b/v2v/windows_virtio.ml
@@ -166,38 +166,9 @@ and add_viostor_to_driver_database g root arch current_cs =
    * one must add keys into the DriverDatabase.
    *)
 
-  let viostor_inf =
-    let arch =
-      match arch with
-      | "x86_64" -> "amd64"
-      | "i386" | "i486" | "i585" | "i686" -> "x86"
-      | _ ->
-         error (f_"when adding viostor to the DriverDatabase, unknown architecture: %s") arch in
-    (* XXX I don't know what the significance of the c863.. string is.  It
-     * may even be random.
-     *)
-    sprintf "viostor.inf_%s_%s" arch "c86329aaeb0a7904" in
-
-  let scsi_adapter_guid = "{4d36e97b-e325-11ce-bfc1-08002be10318}" in
-  (* There should be a key
-   *   HKLM\SYSTEM\DriverDatabase\DeviceIds\<scsi_adapter_guid>
-   * We want to add:
-   *   "oem1.inf"=hex(0):
-   * but if we find "oem1.inf" we'll add "oem2.inf" (etc).
-   *)
-  let oem_inf =
-    let path = [ "DriverDatabase"; "DeviceIds"; scsi_adapter_guid ] in
-    match Windows.get_node g root path with
-    | None ->
-       error (f_"cannot find HKLM\\SYSTEM\\DriverDatabase\\DeviceIds\\%s in the guest registry") scsi_adapter_guid
-    | Some node ->
-       let rec loop node i =
-         let oem_inf = sprintf "oem%d.inf" i in
-         let value = g#hivex_node_get_value node oem_inf in
-         if value = 0_L then oem_inf else loop node (i+1)
-       in
-       let oem_inf = loop node 1 in
-       oem_inf in
+  let drv_inf = "guestor.inf" in
+  let drv_inf_label = drv_inf ^ "_tmp" in
+  let drv_config = "guestor_conf" in
 
   let regedits = [
       [ current_cs; "Services"; "viostor" ],
@@ -207,21 +178,21 @@ and add_viostor_to_driver_database g root arch current_cs =
         "Start", REG_DWORD 0x0_l;
         "Type", REG_DWORD 0x1_l ];
 
-      [ "DriverDatabase"; "DriverInfFiles"; oem_inf ],
-      [ "", REG_MULTI_SZ [ viostor_inf ];
-        "Active", REG_SZ viostor_inf;
-        "Configurations", REG_MULTI_SZ [ "rhelscsi_inst" ]
+      [ "DriverDatabase"; "DriverInfFiles"; drv_inf ],
+      [ "", REG_MULTI_SZ [ drv_inf_label ];
+        "Active", REG_SZ drv_inf_label;
+        "Configurations", REG_MULTI_SZ [ drv_config ]
       ];
 
       [ "DriverDatabase"; "DeviceIds"; "PCI"; "VEN_1AF4&DEV_1001&SUBSYS_00021AF4&REV_00" ],
-      [ oem_inf, REG_BINARY "\x01\xff\x00\x00" ];
+      [ drv_inf, REG_BINARY "\x01\xff\x00\x00" ];
 
-      [ "DriverDatabase"; "DriverPackages"; viostor_inf; "Configurations"; "rhelscsi_inst" ],
+      [ "DriverDatabase"; "DriverPackages"; drv_inf_label; "Configurations"; drv_config ],
       [ "ConfigFlags", REG_DWORD 0_l;
         "Service", REG_SZ "viostor" ];
 
-      [ "DriverDatabase"; "DriverPackages"; viostor_inf; "Descriptors"; "PCI"; "VEN_1AF4&DEV_1001&SUBSYS_00021AF4&REV_00" ],
-      [ "Configuration", REG_SZ "rhelscsi_inst" ]
+      [ "DriverDatabase"; "DriverPackages"; drv_inf_label; "Descriptors"; "PCI"; "VEN_1AF4&DEV_1001&SUBSYS_00021AF4&REV_00" ],
+      [ "Configuration", REG_SZ drv_config ]
     ] in
 
   reg_import g root regedits
-- 
2.5.5