From bf03017c3a390f75130d810bed403008abcbe7f4 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Thu, 1 Jan 1970 00:00:00 +0000 Subject: [PATCH] Read out metadata offset & length from PV header. --- virt-df/virt_df_lvm2.ml | 54 ++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 42 insertions(+), 12 deletions(-) diff --git a/virt-df/virt_df_lvm2.ml b/virt-df/virt_df_lvm2.ml index dc97656..abc247e 100644 --- a/virt-df/virt_df_lvm2.ml +++ b/virt-df/virt_df_lvm2.ml @@ -29,29 +29,58 @@ let plugin_name = "LVM2" let sector_size = 512 let sector_size64 = 512L -let pv_label_offset = sector_size64 - (* Probe to see if it's an LVM2 PV. Look for the "LABELONE" label. *) let rec probe_pv lvm_plugin_id dev = try - let uuid = read_pv_label dev in + let uuid, metadata_offset, metadata_length = read_pv_label dev in + if debug then + eprintf "LVM2 detected UUID %s md offset 0x%lx len %ld\n%!" + uuid metadata_offset metadata_length; { lvm_plugin_id = lvm_plugin_id; pv_uuid = uuid } with _ -> raise Not_found and read_pv_label dev = - (* Load the second sector. *) - let bits = dev#read_bitstring pv_label_offset sector_size in + (* Load the first 8 sectors. I found by experimentation that + * the second sector contains the header ("LABELONE" etc) and + * the nineth sector contains some additional information about + * the location of the current metadata. + *) + let bits = dev#read_bitstring 0L (9 * sector_size) in - (*Bitmatch.hexdump_bitstring stdout bits;*) + Bitmatch.hexdump_bitstring stdout bits; bitmatch bits with - | labelone : 8*8 : bitstring; (* "LABELONE" *) - padding : 16*8 : bitstring; + | sector0 : sector_size*8 : bitstring; (* sector 0 *) + labelone : 8*8 : bitstring; (* "LABELONE" *) + padding : 16*8 : bitstring; (* Seems to contain something. *) lvm2_ver : 8*8 : bitstring; (* "LVM2 001" *) - uuid : 32*8 : bitstring (* UUID *) + uuid : 32*8 : bitstring; (* UUID *) + padding2 : (sector_size-64)*8 : bitstring; (* to end of second sector *) + sector234567 : sector_size*8 * 6 : bitstring; (* sectors 2-6 *) + padding3 : 0x28*8 : bitstring; (* start of sector 8 *) + metadata_offset : 32 : littleendian;(* metadata offset *) + padding4 : 4*8 : bitstring; + metadata_length : 32 : littleendian (* length of metadata (bytes) *) when Bitmatch.string_of_bitstring labelone = "LABELONE" && - Bitmatch.string_of_bitstring lvm2_ver = "LVM2 001" -> - Bitmatch.string_of_bitstring uuid + Bitmatch.string_of_bitstring lvm2_ver = "LVM2 001" -> + let metadata_offset = metadata_offset +* 0x1000_l in + + (* Check the metadata offset & length look reasonable for this + * device. Otherwise maybe it's a newer or older header which + * we don't really understand properly. + *) + let () = + let size = + if dev#size <= Int64.of_int32 Int32.max_int then Int64.to_int32 dev#size + else Int32.max_int in + if metadata_offset < 0x1200_l || metadata_offset >= size + || metadata_length < 0_l || metadata_offset+*metadata_length >= size + then + invalid_arg "read_pv_label: bad metadata offset or length" in + + Bitmatch.string_of_bitstring uuid, metadata_offset, metadata_length + + | _ -> invalid_arg (sprintf "read_pv_label: %s: not an LVM2 physical volume" dev#name) @@ -61,7 +90,8 @@ and read_pv_label dev = * (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 = [] +let list_lvs devs = + [] (* Register with main code. *) let () = -- 1.8.3.1