Add code for formatting a disk

This commit is contained in:
Reynir Björnsson 2024-10-09 18:42:01 +02:00
parent d36a0714e7
commit ceb4674ec2
2 changed files with 114 additions and 12 deletions

View file

@ -12,6 +12,20 @@ module Make(BLOCK : Mirage_block.S) = struct
sha512s : Part.t ;
}
(* I just made these ones up... *)
let tar_guid = Uuidm.of_string "53cd6812-46cc-474e-a141-30b3aed85f53" |> Option.get
let cache_guid = Uuidm.of_string "22ab9cf5-6e51-45c2-998a-862e23aab264" |> Option.get
let git_guid = Uuidm.of_string "30faa50a-4c9d-47ff-a1a5-ecfb3401c027" |> Option.get
(* GPT uses a 72 byte utf16be encoded string for partition names *)
let utf16be_of_ascii s =
String.init 72
(fun i ->
if i mod 2 = 0 && i / 2 < String.length s then
s.[i/2]
else
'\000')
let read_partition_table info block =
let b = Cstruct.create info.Mirage_block.sector_size in
(* We will ignore the protective MBR at lba [0L] *)
@ -38,14 +52,6 @@ module Make(BLOCK : Mirage_block.S) = struct
| Ok gpt -> Lwt.return gpt
let connect block =
let utf16be_of_ascii s =
String.init 72
(fun i ->
if i mod 2 = 0 && i / 2 < String.length s then
s.[i/2]
else
'\000')
in
let* info = BLOCK.get_info block in
let* gpt = read_partition_table info block in
let tar, git_dump, md5s, sha512s =
@ -88,4 +94,79 @@ module Make(BLOCK : Mirage_block.S) = struct
let tar = get_part tar and git_dump = get_part git_dump
and md5s = get_part md5s and sha512s = get_part sha512s in
{ tar ; git_dump ; md5s ; sha512s }
let format block ~sectors_cache ~sectors_git =
let* { size_sectors; sector_size; _ } = BLOCK.get_info block in
let ( let*? ) = Lwt_result.bind in
(* ocaml-gpt uses a fixed size partition entries table. Create an empty GPT
to figure out the first usable LBA *)
let empty =
Gpt.make ~sector_size ~disk_sectors:size_sectors []
|> Result.get_ok
in
let*? () =
if size_sectors <
(* protective MBR + GPT header + GPT table *)
let ( + ) = Int64.add in
empty.first_usable_lba +
min 1L (Int64.of_int (2 * Tar.Header.length / sector_size)) + sectors_cache + sectors_cache + sectors_git
+ 1L (* backup GPT header *) then
Lwt.return_error (`Msg "too small disk")
else Lwt_result.return ()
in
let gpt =
let partitions =
(* Current implementation of [Gpt.Partition.make] only returns [Ok _] or
raises [Invalid_argument _] :/ *)
let attributes = 1L in
let sha512s =
Gpt.Partition.make
~name:(utf16be_of_ascii "sha512s")
~type_guid:cache_guid
~attributes
Int64.(succ (sub empty.last_usable_lba sectors_cache))
empty.last_usable_lba
|> Result.get_ok
in
let md5s =
Gpt.Partition.make
~name:(utf16be_of_ascii "md5s")
~type_guid:cache_guid
~attributes
(Int64.sub sha512s.starting_lba sectors_cache)
(Int64.pred sha512s.starting_lba)
|> Result.get_ok
in
let git_dump =
Gpt.Partition.make
~name:(utf16be_of_ascii "git_dump")
~type_guid:git_guid
~attributes
(Int64.sub md5s.starting_lba sectors_git)
(Int64.pred md5s.starting_lba)
|> Result.get_ok
in
let tar =
Gpt.Partition.make
~name:(utf16be_of_ascii "tar")
~type_guid:tar_guid
~attributes
empty.first_usable_lba
(Int64.pred git_dump.starting_lba)
|> Result.get_ok
in
[ tar; git_dump; md5s; sha512s ]
in
Gpt.make ~sector_size ~disk_sectors:size_sectors partitions
|> Result.get_ok
in
let buf =
Cstruct.create (sector_size * (Int64.to_int gpt.first_usable_lba + 2 * Tar.Header.length))
in
Gptar.marshal_header ~sector_size buf gpt;
Gpt.marshal_partition_table ~sector_size
(Cstruct.shift buf (sector_size * Int64.to_int gpt.partition_entry_lba))
gpt;
BLOCK.write block 0L [ buf ]
|> Lwt_result.map_error (fun e -> `Block e)
end

View file

@ -44,15 +44,20 @@ module K = struct
Mirage_runtime.register_arg Arg.(value & opt int 80 doc)
let sectors_cache =
let doc = "Number of sectors reserved for each checksum cache (md5, sha512)." in
let doc = "Number of sectors reserved for each checksum cache (md5, sha512). Only used with --initialize-disk." in
let doc = Arg.info ~doc ["sectors-cache"] in
Mirage_runtime.register_arg Arg.(value & opt int64 Int64.(mul 4L 2048L) doc)
let sectors_git =
let doc = "Number of sectors reserved for git dump." in
let doc = "Number of sectors reserved for git dump. Only used with --initialize-disk" in
let doc = Arg.info ~doc ["sectors-git"] in
Mirage_runtime.register_arg Arg.(value & opt int64 Int64.(mul 40L (mul 2L 1024L)) doc)
let initialize_disk =
let doc = "Initialize the disk with a partition table. THIS IS DESTRUCTIVE!" in
let doc = Arg.info ~doc ["initialize-disk"] in
Mirage_runtime.register_arg Arg.(value & flag doc)
let ignore_local_git =
let doc = "Ignore restoring locally saved git repository." in
let doc = Arg.info ~doc ["ignore-local-git"] in
@ -984,8 +989,7 @@ stamp: %S
module Paf = Paf_mirage.Make(Stack.TCP)
let start block _time _pclock stack git_ctx http_ctx =
Part.connect block >>= fun { Part.tar ; git_dump; md5s ; sha512s } ->
let start_mirror { Part.tar; git_dump; md5s; sha512s } stack git_ctx http_ctx =
KV.connect tar >>= fun kv ->
Cache.connect git_dump >>= fun git_dump ->
Cache.connect md5s >>= fun md5s ->
@ -1036,4 +1040,21 @@ stamp: %S
go ());
download_archives (K.parallel_downloads ()) disk http_ctx git_kv >>= fun () ->
(th >|= fun _v -> ())
let start block _time _pclock stack git_ctx http_ctx =
let initialize_disk = K.initialize_disk ()
and sectors_cache = K.sectors_cache ()
and sectors_git = K.sectors_git () in
if initialize_disk then
Part.format block ~sectors_cache ~sectors_git >>= function
| Ok () -> Lwt.return_unit
| Error `Msg e ->
Logs.err (fun m -> m "Error formatting disk: %s" e);
exit Mirage_runtime.argument_error
| Error `Block e ->
Logs.err (fun m -> m "Error formatting disk: %a" BLOCK.pp_write_error e);
exit 2
else
Part.connect block >>= fun parts ->
start_mirror parts stack git_ctx http_ctx
end