LVM2 PV detection.

[virt-top.git] / virt-df / virt_df_lvm2.ml

diff --git a/virt-df/virt_df_lvm2.ml b/virt-df/virt_df_lvm2.ml
index d01a5a8..9355597 100644 (file)
--- a/virt-df/virt_df_lvm2.ml
+++ b/virt-df/virt_df_lvm2.ml
@@ -22,18 +22,43 @@
 
 open Printf
 open Virt_df_gettext.Gettext
+open Virt_df
 
-(* Int64 operators for convenience. *)
-let (+^) = Int64.add
-let (-^) = Int64.sub
-let ( *^ ) = Int64.mul
-let (/^) = Int64.div
+let sector_size = 512
+let sector_size64 = 512L
 
-let probe_lvm2 target part_type fd start size =
-  Virt_df.ProbeFailed (s_ "LVM2 not supported yet")
+let pv_label_offset = sector_size64
+
+(* Probe to see if it's an LVM2 PV.  Look for the "LABELONE" label. *)
+let rec probe_pv dev =
+  try ignore (read_pv_label dev); true
+  with _ -> false
+
+and read_pv_label dev =
+  (* Load the second sector. *)
+  let bits = dev#read_bitstring pv_label_offset sector_size in
+
+  Bitmatch.hexdump_bitstring stdout bits;
+
+  bitmatch bits with
+  | labelone : 8*8 : bitstring;                (* "LABELONE" *)
+    padding : 16*8 : bitstring;
+    lvm2_ver : 8*8 : bitstring;                (* "LVM2 001" *)
+    uuid : 32*8 : bitstring            (* UUID *)
+      when Bitmatch.string_of_bitstring labelone = "LABELONE" &&
+       Bitmatch.string_of_bitstring lvm2_ver = "LVM2 001" ->
+    uuid
+  | _ ->
+    invalid_arg (sprintf "read_pv_label: %s: not an LVM2 physical volume"
+                  dev#name)
+
+(* We are passed a list of devices which we previously identified
+ * as PVs belonging to us.  From these produce a list of all LVs
+ * (as devices) and return them.  Note that we don't try to detect
+ * what is on these LVs - that will be done in the main code.
+ *)
+let list_lvs devs = []
 
 (* Register with main code. *)
 let () =
-  Virt_df.fs_register
-    [ 0x8e ]                           (* Partition type. *)
-    probe_lvm2
+  lvm_type_register "LVM2" probe_pv list_lvs