upstream: https://github.com/mirage/ocaml-mbr
feat(mbr,gpt): migrate MBR and GPT binary codecs to Wire.Codec
Replace hand-written get/set helpers and explicit offset constants with
type-safe Wire.Codec definitions for MBR partition entries (16 bytes),
GPT partition entries (128 bytes), and GPT headers (92 bytes). Add Wire
roundtrip tests for all three structures.
+76
-40
+1
-1
lib/dune
+1
-1
lib/dune
+37
-37
lib/mbr.ml
+37
-37
lib/mbr.ml
···
161
161
else Error "partition parameters do not fit in int32"
162
162
163
163
let sizeof = 16
164
-
let status_offset = 0
165
-
let first_absolute_sector_chs_offset = 1
166
-
let ty_offset = 4
167
-
let last_absolute_sector_chs_offset = 5
168
-
let first_absolute_sector_lba_offset = 8
169
-
let sectors_offset = 12
164
+
165
+
let codec =
166
+
let open Wire.Codec in
167
+
let decode_chs s =
168
+
let heads = Char.code s.[0] in
169
+
let y = Char.code s.[1] in
170
+
let z = Char.code s.[2] in
171
+
{ Geometry.cylinders = (y lsl 2) lor z; heads; sectors = y land 0x3F }
172
+
in
173
+
record "MbrPartition" (fun status first_chs ty last_chs lba sectors ->
174
+
{
175
+
active = status = 0x80;
176
+
first_absolute_sector_chs = decode_chs first_chs;
177
+
ty;
178
+
last_absolute_sector_chs = decode_chs last_chs;
179
+
first_absolute_sector_lba = Int32.of_int (Wire.UInt32.to_int lba);
180
+
sectors = Int32.of_int (Wire.UInt32.to_int sectors);
181
+
})
182
+
|+ field "status" Wire.uint8 (fun t -> if t.active then 0x80 else 0)
183
+
|+ field "first_chs"
184
+
(Wire.byte_array ~size:(Wire.int 3))
185
+
(fun _ -> "\000\000\000")
186
+
|+ field "type" Wire.uint8 (fun t -> t.ty)
187
+
|+ field "last_chs"
188
+
(Wire.byte_array ~size:(Wire.int 3))
189
+
(fun _ -> "\000\000\000")
190
+
|+ field "lba_start" Wire.uint32 (fun t ->
191
+
Wire.UInt32.of_int (Int32.to_int t.first_absolute_sector_lba))
192
+
|+ field "sectors" Wire.uint32 (fun t ->
193
+
Wire.UInt32.of_int (Int32.to_int t.sectors))
194
+
|> seal
195
+
196
+
let struct_ = Wire.Codec.to_struct codec
170
197
171
198
let unmarshal buf off =
172
199
let* () =
···
177
204
sizeof)
178
205
else Ok ()
179
206
in
180
-
let ty = get_u8 buf (off + ty_offset) in
181
-
if ty == 0x00 then
207
+
let p = Wire.Codec.decode codec buf off in
208
+
if p.ty = 0x00 then
182
209
if bytes_all_zero buf off sizeof then Ok None
183
210
else Error "Non-zero empty partition type"
184
-
else
185
-
let active = get_u8 buf (off + status_offset) = 0x80 in
186
-
let* first_absolute_sector_chs =
187
-
Geometry.unmarshal buf (off + first_absolute_sector_chs_offset)
188
-
in
189
-
let* last_absolute_sector_chs =
190
-
Geometry.unmarshal buf (off + last_absolute_sector_chs_offset)
191
-
in
192
-
let first_absolute_sector_lba =
193
-
get_u32_le buf (off + first_absolute_sector_lba_offset)
194
-
in
195
-
let sectors = get_u32_le buf (off + sectors_offset) in
196
-
Ok
197
-
(Some
198
-
{
199
-
active;
200
-
first_absolute_sector_chs;
201
-
ty;
202
-
last_absolute_sector_chs;
203
-
first_absolute_sector_lba;
204
-
sectors;
205
-
})
211
+
else Ok (Some p)
206
212
207
-
let marshal (buf : bytes) off t =
208
-
set_u8 buf (off + status_offset) (if t.active then 0x80 else 0);
209
-
set_u8 buf (off + ty_offset) t.ty;
210
-
set_u32_le buf
211
-
(off + first_absolute_sector_lba_offset)
212
-
t.first_absolute_sector_lba;
213
-
set_u32_le buf (off + sectors_offset) t.sectors
213
+
let marshal (buf : bytes) off t = Wire.Codec.encode codec t buf off
214
214
end
215
215
216
216
type t = {
+6
lib/mbr.mli
+6
lib/mbr.mli
···
68
68
[make ?active ~partition_type (Int64.to_int32 sector_start)
69
69
(Int64.to_int32 size_sectors)] when both [sector_start] and
70
70
[size_sectors] fit in int32. Otherwise [Error _]. *)
71
+
72
+
val codec : t Wire.Codec.t
73
+
(** Wire codec for a 16-byte MBR partition entry. *)
74
+
75
+
val struct_ : Wire.struct_
76
+
(** Wire struct definition for a partition entry. *)
71
77
end
72
78
73
79
type t = private {
+1
-1
test/dune
+1
-1
test/dune
+31
-1
test/test_mbr.ml
+31
-1
test/test_mbr.ml
···
118
118
("make sorts partitions", `Quick, test_make_sorted);
119
119
]
120
120
121
+
let test_partition_wire_size () =
122
+
Alcotest.(check int)
123
+
"partition wire_size" 16
124
+
(Wire.Codec.wire_size Mbr.Partition.codec)
125
+
126
+
let test_partition_wire_roundtrip () =
127
+
let p =
128
+
get_ok
129
+
(Mbr.Partition.make ~active:true ~partition_type:0x83
130
+
Mbr.default_partition_start 204800l)
131
+
in
132
+
let buf = Bytes.create 16 in
133
+
Wire.Codec.encode Mbr.Partition.codec p buf 0;
134
+
let p' = Wire.Codec.decode Mbr.Partition.codec buf 0 in
135
+
Alcotest.(check bool) "active" p.active p'.active;
136
+
Alcotest.(check int) "ty" p.ty p'.ty;
137
+
Alcotest.(check int32)
138
+
"lba_start" p.first_absolute_sector_lba p'.first_absolute_sector_lba;
139
+
Alcotest.(check int32) "sectors" p.sectors p'.sectors
140
+
141
+
let suite_wire =
142
+
[
143
+
("Partition.codec wire_size = 16", `Quick, test_partition_wire_size);
144
+
("Partition wire roundtrip", `Quick, test_partition_wire_roundtrip);
145
+
]
146
+
121
147
let () =
122
148
Alcotest.run "Mbr"
123
-
[ ("Mbr.Partition.make", suite_partition_make); ("Mbr.make", suite_make) ]
149
+
[
150
+
("Mbr.Partition.make", suite_partition_make);
151
+
("Mbr.make", suite_make);
152
+
("Wire", suite_wire);
153
+
]