1 (* 'df' command for virtual domains.
3 (C) Copyright 2007 Richard W.M. Jones, Red Hat Inc.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 Support for Master Boot Record partition scheme.
27 open Virt_df_gettext.Gettext
31 let sector_size64 = 512L
33 (* Maximum number of extended partitions possible. *)
34 let max_extended_partitions = 100
36 (* Device representing a single partition. It just acts as an offset
37 * into the underlying device.
40 * (1) 'start'/'size' are measured in sectors.
41 * (2) 'partno' is the partition number, starting at 1
42 * (cf. /dev/hda1 is the first partition).
43 * (3) 'dev' is the underlying block device.
45 class partition_device partno start size dev =
46 let devname = dev#name in
47 let name = sprintf "%s%d" devname partno in
48 let start = start *^ sector_size64 in
49 let size = size *^ sector_size64 in
51 inherit offset_device name start size dev
55 {{:http://en.wikipedia.org/wiki/Master_boot_record}master boot record}
56 (if it is one) and read the partitions.
58 @raise Not_found if it is not an MBR.
60 let rec probe_mbr dev =
61 (* Read the first sector. *)
63 try dev#read_bitstring 0L sector_size
64 with exn -> raise Not_found in
66 (* Does this match a likely-looking MBR? *)
68 | { _ : 3568 : bitstring; (* padding to byte offset 446 *)
69 part0 : 128 : bitstring; (* partitions *)
70 part1 : 128 : bitstring;
71 part2 : 128 : bitstring;
72 part3 : 128 : bitstring;
73 0x55 : 8; 0xAA : 8 } -> (* MBR signature *)
75 (* Parse the partition table entries. *)
77 List.mapi (parse_mbr_entry dev) [part0;part1;part2;part3] in
80 (* Read extended partition data. *)
81 let extendeds = List.map (
83 | { part_type = 0x05 } as part ->
84 probe_extended_partition
85 max_extended_partitions fd part part.part_lba_start
88 let extendeds = List.concat extendeds in
91 { parts_name = "MBR"; parts = primaries }
94 raise Not_found (* not an MBR *)
96 (* Parse a single partition table entry. See the table here:
97 * http://en.wikipedia.org/wiki/Master_boot_record
99 and parse_mbr_entry dev i bits =
101 | { 0l : 32; 0l : 32; 0l : 32; 0l : 32 } ->
102 { part_status = NullEntry; part_type = 0;
103 part_dev = null_device; part_content = `Unknown }
105 | { ((0|0x80) as bootable) : 8; first_chs : 24;
106 part_type : 8; last_chs : 24;
107 first_lba : 32 : unsigned, littleendian;
108 part_size : 32 : unsigned, littleendian } ->
109 let bootable = if bootable = 0 then Nonbootable else Bootable in
110 make_mbr_entry bootable dev (i+1) part_type first_lba part_size
113 { part_status = Malformed; part_type = 0;
114 part_dev = null_device; part_content = `Unknown }
116 and make_mbr_entry part_status dev partno part_type first_lba part_size =
117 let first_lba = uint64_of_int32 first_lba in
118 let part_size = uint64_of_int32 part_size in
120 eprintf "make_mbr_entry: first_lba = %Lx part_size = %Lx\n%!"
122 { part_status = part_status;
123 part_type = part_type;
124 part_dev = new partition_device partno first_lba part_size dev;
125 part_content = `Unknown }
128 This code worked previously, but now needs some love ...
131 (* Probe an extended partition. *)
132 and probe_extended_partition max fd epart sect =
134 (* Offset of the first EBR. *)
135 let ebr_offs = sect *^ sector_size in
137 LargeFile.lseek fd (ebr_offs +^ 510L) SEEK_SET;
138 let str = String.create 2 in
139 if read fd str 0 2 <> 2 || str.[0] != '\x55' || str.[1] != '\xAA' then
142 (* Read the extended partition table entries (just 2 of them). *)
143 LargeFile.lseek fd (ebr_offs +^ 446L) SEEK_SET;
144 let str = String.create 32 in
145 if read fd str 0 32 <> 32 then
146 failwith (s_ "error reading extended partition")
148 (* Extract partitions from the data. *)
150 match List.map (get_partition str) [ 0; 16 ] with
152 | _ -> failwith (s_ "probe_extended_partition: internal error") in
153 (* First partition entry has offset to the start of this partition. *)
154 let part1 = { part1 with
155 part_lba_start = sect +^ part1.part_lba_start } in
156 (* Second partition entry is zeroes if end of list, otherwise points
157 * to the next partition.
159 if part2.part_status = NullEntry then
162 part1 :: probe_extended_partition
163 (max-1) fd epart (sect +^ part2.part_lba_start)
170 (* Ugh, fake a UInt32 -> UInt64 conversion without sign extension, until
171 * we get working UInt32/UInt64 modules in extlib.
173 and uint64_of_int32 u32 =
174 let i64 = Int64.of_int32 u32 in
175 if u32 >= 0l then i64
176 else Int64.add i64 0x1_0000_0000_L
178 (* Register with main code. *)
179 let () = partition_type_register "MBR" probe_mbr