Přemysl Eric Janouch
019c4302ad
Lua detection functions used to cause fatal errors on failure to read. We could also reconsider treating detection errors as fatal.
91 lines
3.2 KiB
Lua
91 lines
3.2 KiB
Lua
--
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-- vdi.lua: VirtualBox Disk Image
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--
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-- Copyright (c) 2017, Přemysl Eric Janouch <p@janouch.name>
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--
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-- Permission to use, copy, modify, and/or distribute this software for any
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-- purpose with or without fee is hereby granted.
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--
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-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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--
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local detect = function (c)
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if #c < 68 then
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return false
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end
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c.position = 65
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return c:read (4) == "\x7F\x10\xDA\xBE"
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end
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-- As described by https://forums.virtualbox.org/viewtopic.php?t=8046
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local decode = function (c)
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if not detect (c ()) then error ("not a VDI file") end
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c.endianity = "le"
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-- The header is preceded by an arbitrary string
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c.position = 65
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local signature = c:u32 ("image signature")
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local p, vmajor, vminor = c.position, c:u16 (), c:u16 ()
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c (p, c.position - 1):mark ("VDI version: %d.%d", vmajor, vminor)
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local size = c:u32 ("size of header: %d")
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c (64 + 1, 64 + size):mark ("VDI header")
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local type = c:u32 ("image type: %s", function (u32)
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if u32 == 1 then return "dynamic" end
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if u32 == 2 then return "static" end
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return "unknown: %d", u32
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end)
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local flags = c:u32 ("image flags: %#x")
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local p, desc = c.position, c:read (256)
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c (p, c.position - 1):mark ("image description: %s", desc:match ("%C+"))
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local offset_blocks = c:u32 ("offset to blocks: %#x")
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local offset_data = c:u32 ("offset to data: %#x")
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local n_cylinders = c:u32 ("#cylinders: %d")
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local n_heads = c:u32 ("#heads: %d")
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local n_sectors = c:u32 ("#sectors: %d")
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local sector_size = c:u32 ("sector size: %d")
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local unused = c:read (4)
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local disk_size = c:u64 ("disk size: %d bytes")
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local block_size = c:u32 ("block size: %d")
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-- TODO: we should probably count that in -> is it in "blocks" or "data"?
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local block_extra_data = c:u32 ("block extra data: %d")
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local n_blocks = c:u32 ("#blocks in HDD: %d")
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local n_blocks_allocated = c:u32 ("#blocks allocated: %d")
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local function read_uuid4 (c, name)
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local p, uuid = c.position, c:read (16)
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local b = table.pack (uuid:byte (1, #uuid))
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c (p, c.position - 1):mark ("%s: %02x%02x%02x%02x-"
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.. "%02x%02x-%02x%02x-%02x%02x-"
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.. "%02x%02x%02x%02x%02x%02x", name,
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b[1], b[2], b[3], b[4],
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b[5], b[6], b[7], b[8], b[9], b[10],
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b[11], b[12], b[13], b[14], b[15], b[16])
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return uuid
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end
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local uuid_vdi = read_uuid4 (c, "UUID of VDI")
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local uuid_last_snap = read_uuid4 (c, "UUID of last snapshot")
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local uuid_link = read_uuid4 (c, "UUID of link")
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local uuid_parent = read_uuid4 (c, "UUID of parent")
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-- TODO: perhaps this should be more granular and identify all blocks
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c (offset_blocks + 1, offset_blocks + 4 * n_blocks)
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:mark ("VDI blocks")
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c (offset_data + 1, offset_data + block_size * n_blocks_allocated)
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:mark ("VDI data")
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end
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hex.register { type="vdi", detect=detect, decode=decode }
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