upstream: https://github.com/mirage/ocaml-gpt
ocaml-gpt: rewrite README examples to typecheck
The blocks chained [match ... with | Error -> ...] expressions at module
top level (which doesn't parse) and referenced unbound [reader],
[writer], [header_bytes], [read_sectors]. Recast each block as a
function or a top-level binding ladder so the snippets typecheck and
are self-contained.
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README.md
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README.md
···
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### Creating partitions and GPT
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```ocaml
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-
(* Create a partition entry *)
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let type_guid =
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Uuidm.of_string "C12A7328-F81F-11D2-BA4B-00A0C93EC93B" |> Option.get
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in
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match Gpt.Partition.make ~type_guid ~attributes:0L 2048L 1048575L with
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| Error e -> failwith e
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| Ok part ->
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(* Build the GPT *)
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-
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match Gpt.v ~disk_sectors:2097152L ~sector_size:512 [ part ] with
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+
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let part =
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match Gpt.Partition.make ~type_guid ~attributes:0L 2048L 1048575L with
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| Ok p -> p
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| Error e -> failwith e
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+
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let gpt =
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match Gpt.v ~disk_sectors:2097152L ~sector_size:512 [ part ] with
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| Ok g -> g
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| Error e -> failwith e
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| Ok gpt -> Fmt.pr "%a@." Gpt.pp gpt
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+
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let () = Fmt.pr "%a@." Gpt.pp gpt
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```
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### Reading from bytes
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```ocaml
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match Gpt.of_string header_bytes ~sector_size:512 with
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| Error e -> failwith e
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| Ok (`Read_partition_table (lba, num_sectors), k) ->
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(* Read partition table at the given LBA *)
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-
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let table_bytes = read_sectors lba num_sectors
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match k table_bytes with
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| Ok gpt -> Fmt.pr "%a@." Gpt.pp gpt
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let parse_gpt ~read_sectors header_bytes =
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match Gpt.of_string header_bytes ~sector_size:512 with
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| Error e -> failwith e
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| Ok (`Read_partition_table (lba, num_sectors), k) ->
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let table_bytes = read_sectors lba num_sectors in
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(match k table_bytes with
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| Ok gpt -> gpt
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| Error e -> failwith e)
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```
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### Streaming I/O with bytesrw
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```ocaml
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-
(* Read *)
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match Gpt.read reader ~sector_size:512 with
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| Ok gpt -> Fmt.pr "%a@." Gpt.pp gpt
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| Error e -> failwith e
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let read_gpt reader =
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match Gpt.read reader ~sector_size:512 with
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| Ok gpt -> gpt
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| Error e -> failwith e
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(* Write *)
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Gpt.write_header writer ~sector_size:512 ~primary:true gpt;
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Gpt.write_partition_table writer ~sector_size:512 gpt
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let write_gpt writer gpt =
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Gpt.write_header writer ~sector_size:512 ~primary:true gpt;
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Gpt.write_partition_table writer ~sector_size:512 gpt
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```
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### Protective MBR