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open CFStream
module Default = struct
let zlib_buffer_size = 4096
let level = 3
end
module Error = struct
type unzip =
[ `garbage_at_end_of_compressed_data of string
| `zlib of string
| `wrong_gzip_header of
[ `compression_method | `flags | `magic_number ] * int ]
[@@deriving sexp]
(** The possible unzipping errors. *)
type t = unzip [@@deriving sexp]
end
module Transform = struct
let buffer =
let open Result.Monad_infix in
let bytes_read = ref 0 in
let ignore_bytes n = bytes_read := !bytes_read + n in
let assert_byte f error =
let byte = (Char.to_int (Bytes.get buffer (!bytes_read))) in
if f byte
then (incr bytes_read; Ok byte)
else Error (`wrong_gzip_header (error, byte)) in
let assert_byte_eq b error = assert_byte ((=) b) error in
let read_byte () =
let byte = (Char.to_int (Bytes.get buffer (!bytes_read))) in
(incr bytes_read; Ok byte) in
let rec skip_null_terminated () =
read_byte () >>= fun x ->
if x = 0 then Ok () else skip_null_terminated () in
assert_byte_eq 0x1f `magic_number >>= fun _ ->
assert_byte_eq 0x8b `magic_number >>= fun _ ->
assert_byte_eq 8 `compression_method >>= fun _ ->
assert_byte (fun b -> b land 0xe0 = 0) `flags >>= fun flags ->
ignore_bytes 6;
(if flags land 0x04 <> 0 then (
read_byte () >>= fun len1 ->
read_byte () >>= fun len2 ->
ignore_bytes (len1 + len2 lsl 8);
Ok ()
) else Ok ())
>>= fun () ->
(if flags land 0x08 <> 0 then skip_null_terminated () else Ok ())
>>= fun () ->
(if flags land 0x10 <> 0 then skip_null_terminated () else Ok ())
>>= fun () ->
if flags land 0x02 <> 0 then begin
ignore_bytes 2;
end;
if !bytes_read > Bytes.length buffer then
failwith "NOT-YET"
else
Ok !bytes_read
let inflate_as_much_as_possible in_buffer buffer
zstream zlib_write_buffer zlib_buffer_size format =
let len = Bytes.length buffer in
let try_to_output used_out =
if used_out > 0
then (`output (Ok (Bytes.To_string.sub zlib_write_buffer ~pos:0 ~len:used_out)))
else (`not_ready) in
let (finished, used_in, used_out) =
Zlib.inflate zstream buffer 0 len
zlib_write_buffer 0 zlib_buffer_size
Zlib.Z_SYNC_FLUSH in
if used_in < len then (
if finished then (
match format with
| `gzip when len - used_in >= 8 ->
let continue_after_gzip = len - used_in > 8 in
if continue_after_gzip then
Buffer.add_string in_buffer
(Bytes.To_string.sub buffer ~pos:(used_in + 8) ~len:(len - used_in - 8));
`finished_gzip (try_to_output used_out)
| `gzip ->
Buffer.add_string in_buffer
Bytes.To_string.(sub buffer ~pos:used_in ~len:(len - used_in));
try_to_output used_out
| _ ->
`error (`garbage_at_end_of_compressed_data
Bytes.To_string.(sub buffer ~pos:used_in ~len:(len - used_in)))
) else (
Buffer.add_string in_buffer
Bytes.To_string.(sub buffer ~pos:used_in ~len:(len - used_in));
try_to_output used_out
)
) else try_to_output used_out
let unzip ?(format=`raw) ?(zlib_buffer_size=Default.zlib_buffer_size) () =
let zstream = ref (Zlib.inflate_init false) in
let in_buffer = Buffer.create 42 in
let zlib_write_buffer = Bytes.create zlib_buffer_size in
let current_state =
ref (match format with `gzip -> `gzip_header | `raw -> `inflate) in
let rec next stopped =
let buffered = Buffer.contents_bytes in_buffer in
let len = Bytes.length buffered in
Buffer.clear in_buffer;
begin match len with
| 0 -> if stopped then `end_of_stream else `not_ready
| _ ->
begin match !current_state with
| `inflate ->
begin
try
let inflation =
inflate_as_much_as_possible in_buffer buffered
!zstream zlib_write_buffer zlib_buffer_size format in
begin match inflation with
| `output o -> `output o
| `error e -> `output (Error e)
| `not_ready -> `not_ready
| `finished_gzip out ->
current_state := `gzip_header;
zstream := Zlib.inflate_init false;
out
end
with
| e ->
`output (Error (`zlib (Exn.to_string e)))
end
| `gzip_header ->
begin
try
match try_skip_gzip_header_exn buffered with
| Ok bytes_read ->
current_state := `inflate;
Buffer.add_string in_buffer
Bytes.To_string.(sub buffered ~pos:bytes_read ~len:(len - bytes_read));
next stopped
| Error e -> `output (Error e)
with
_ -> Buffer.add_bytes in_buffer buffered; `not_ready
end
end
end
in
Tfxm.make_result ()
~feed:(fun string -> Buffer.add_string in_buffer string;) ~next
let =
"\x1F\x8B\x08\x00\
\x00\x00\x00\x00\
\x00\xff"
let bytes_empty () = Bytes.make 0 ' '
let zip ?(format=`raw)
?(level=Default.level) ?(zlib_buffer_size=Default.zlib_buffer_size) () =
let zstream = ref (Zlib.deflate_init level false) in
let in_buffer = Buffer.create 42 in
let zlib_write_buffer = Bytes.create zlib_buffer_size in
let state =
ref (match format with `raw -> `deflating | `gzip -> `gzip_header) in
let this_is_the_end = ref false in
let update_crc, output_crc =
match format with
| `raw -> ((fun _ _ -> ()), (fun () -> bytes_empty ()))
| `gzip ->
let gzip_crc = ref 0l in
let gzip_size = ref 0l in
((fun buf used_in ->
gzip_crc := Zlib.update_crc !gzip_crc buf 0 used_in;
gzip_size := Int32.(!gzip_size + (of_int_exn used_in));
()),
(fun () ->
let buf = Bytes.create 8 in
Binary_packing.pack_signed_32
~byte_order:`Little_endian ~pos:0 ~buf !gzip_crc;
Binary_packing.pack_signed_32
~byte_order:`Little_endian ~pos:4 ~buf !gzip_size;
buf))
in
let next stopped =
match state.contents with
| `gzip_header -> state := `deflating; `output gzip_default_header
| `deflating ->
let buffered = Buffer.contents_bytes in_buffer in
begin match Bytes.length buffered with
| 0 ->
if stopped
then begin
if !this_is_the_end then `end_of_stream
else begin
let (_, _, used_out) =
Zlib.deflate !zstream (bytes_empty ()) 0 0
zlib_write_buffer 0 zlib_buffer_size Zlib.Z_FINISH in
let to_output =
if used_out < zlib_buffer_size then (
this_is_the_end := true;
Zlib.deflate_end !zstream;
(Bytes.To_string.sub zlib_write_buffer ~pos:0 ~len:used_out) ^ (Bytes.to_string (output_crc ()))
) else (
Bytes.To_string.sub zlib_write_buffer ~pos:0 ~len:used_out
) in
`output to_output
end
end
else `not_ready
| len ->
Buffer.clear in_buffer;
let (_, used_in, used_out) =
Zlib.deflate !zstream buffered 0 len
zlib_write_buffer 0 zlib_buffer_size
Zlib.Z_SYNC_FLUSH
in
update_crc buffered used_in;
if used_in < len
then (Buffer.add_subbytes in_buffer
buffered ~pos:used_in ~len:(Bytes.length buffered - used_in));
if used_out > 0 then
`output Bytes.To_string.(sub zlib_write_buffer ~pos:0 ~len:used_out)
else
`not_ready
end
in
Tfxm.make ()
~feed:(fun string -> Buffer.add_string in_buffer string;) ~next
end
let unzip_in_channel ?format ?zlib_buffer_size ?buffer_size inp =
let t = Transform.unzip ?format ?zlib_buffer_size () in
Tfxm.in_channel_strings_to_stream ?buffer_size inp t
let zip_in_channel ?format ?zlib_buffer_size ?level ?buffer_size inp =
let t = Transform.zip ?format ?zlib_buffer_size ?level () in
Tfxm.in_channel_strings_to_stream ?buffer_size inp t
exception Error of Error.unzip
let error_to_exn e = Error e
let unzip_in_channel_exn ?format ?zlib_buffer_size ?buffer_size inp =
Stream.result_to_exn ~error_to_exn
(unzip_in_channel ?format ?zlib_buffer_size ?buffer_size inp)