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--
-- vdi.lua: VirtualBox Disk Image
--
-- Copyright (c) 2017, Přemysl Janouch <p@janouch.name>
--
-- Permission to use, copy, modify, and/or distribute this software for any
-- purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
--
local detect = function (c)
c.position = 65
return c:read (4) == "\x7F\x10\xDA\xBE"
end
-- As described by https://forums.virtualbox.org/viewtopic.php?t=8046
local decode = function (c)
if not detect (c ()) then error ("not a VDI file") end
c.endianity = "le"
-- The header is preceded by an arbitrary string
c.position = 65
local signature = c:u32 ("image signature")
local p, vmajor, vminor = c.position, c:u16 (), c:u16 ()
c (p, c.position - 1):mark ("VDI version: %d.%d", vmajor, vminor)
local size = c:u32 ("size of header: %d")
c (64 + 1, 64 + size):mark ("VDI header")
local type = c:u32 ("image type: %s", function (u32)
if u32 == 1 then return "dynamic" end
if u32 == 2 then return "static" end
return "unknown: %d", u32
end)
local flags = c:u32 ("image flags: %#x")
local p, desc = c.position, c:read (256)
c (p, c.position - 1):mark ("image description: %s", desc:match ("%C+"))
local offset_blocks = c:u32 ("offset to blocks: %#x")
local offset_data = c:u32 ("offset to data: %#x")
local n_cylinders = c:u32 ("#cylinders: %d")
local n_heads = c:u32 ("#heads: %d")
local n_sectors = c:u32 ("#sectors: %d")
local sector_size = c:u32 ("sector size: %d")
local unused = c:read (4)
local disk_size = c:u64 ("disk size: %d bytes")
local block_size = c:u32 ("block size: %d")
-- TODO: we should probably count that in -> is it in "blocks" or "data"?
local block_extra_data = c:u32 ("block extra data: %d")
local n_blocks = c:u32 ("#blocks in HDD: %d")
local n_blocks_allocated = c:u32 ("#blocks allocated: %d")
local function read_uuid4 (c, name)
local p, uuid = c.position, c:read (16)
local b = table.pack (uuid:byte (1, #uuid))
c (p, c.position - 1):mark ("%s: %02x%02x%02x%02x-"
.. "%02x%02x-%02x%02x-%02x%02x-"
.. "%02x%02x%02x%02x%02x%02x", name,
b[1], b[2], b[3], b[4],
b[5], b[6], b[7], b[8], b[9], b[10],
b[11], b[12], b[13], b[14], b[15], b[16])
return uuid
end
local uuid_vdi = read_uuid4 (c, "UUID of VDI")
local uuid_last_snap = read_uuid4 (c, "UUID of last snapshot")
local uuid_link = read_uuid4 (c, "UUID of link")
local uuid_parent = read_uuid4 (c, "UUID of parent")
-- TODO: perhaps this should be more granular and identify all blocks
c (offset_blocks + 1, offset_blocks + 4 * n_blocks)
:mark ("VDI blocks")
c (offset_data + 1, offset_data + block_size * n_blocks_allocated)
:mark ("VDI data")
end
hex.register { type="vdi", detect=detect, decode=decode }
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