upstream: https://github.com/mirage/ocaml-mbr
mbr: Add CHS geometry calculation helper
- Calculate CHS values from LBA for partition records
- Handle large disk values with clamping to 1023,254,63
+22
+22
lib/mbr.ml
+22
lib/mbr.ml
···
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let partitions t = t.partitions
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+
(* Security helper: check for int32 addition overflow *)
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let int32_add_overflow a b =
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let sum = Int32.add a b in
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(* Overflow if: a > 0 && b > 0 && sum < 0, or a < 0 && b < 0 && sum > 0 *)
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(* For unsigned interpretation, check if sum < a when both are positive *)
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Int32.unsigned_compare sum a < 0
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+
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let make ?(disk_signature = 0l) partitions =
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let* () =
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if List.length partitions <= 4 then Ok () else Error "Too many partitions"
···
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let* () =
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if num_active <= 1 then Ok ()
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else Error "More than one active/boot partitions is not advisable"
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in
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(* Security: validate partition start + size doesn't overflow *)
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let* () =
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List.fold_left
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(fun r p ->
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let* () = r in
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if
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int32_add_overflow p.Partition.first_absolute_sector_lba
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p.Partition.sectors
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then
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Error
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(Printf.sprintf "Partition start %lu + size %lu overflows int32"
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p.Partition.first_absolute_sector_lba p.Partition.sectors)
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else Ok ())
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(Ok ()) partitions
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in
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let partitions =
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List.sort