%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2017. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
%%
-module(raw_file_io_inflate).
-behavior(gen_statem).
-export([init/1, callback_mode/0, terminate/3]).
-export([opening/3, opened_gzip/3, opened_passthrough/3]).
-include("file_int.hrl").
-define(INFLATE_CHUNK_SIZE, (1 bsl 10)).
-define(GZIP_WBITS, (16 + 15)).
callback_mode() -> state_functions.
init({Owner, Secret, [compressed]}) ->
Monitor = monitor(process, Owner),
%% We're using the undocumented inflateInit/3 to open the stream in
%% 'reset mode', which resets the inflate state at the end of every stream,
%% allowing us to read concatenated gzip files.
Z = zlib:open(),
ok = zlib:inflateInit(Z, ?GZIP_WBITS, reset),
Data =
#{ owner => Owner,
monitor => Monitor,
secret => Secret,
position => 0,
buffer => prim_buffer:new(),
zlib => Z },
{ok, opening, Data}.
%% The old driver fell back to plain reads if the file didn't start with the
%% magic gzip bytes.
choose_decompression_state(PrivateFd) ->
State =
case ?CALL_FD(PrivateFd, read, [2]) of
{ok, <<16#1F, 16#8B>>} -> opened_gzip;
_Other -> opened_passthrough
end,
{ok, 0} = ?CALL_FD(PrivateFd, position, [0]),
State.
opening({call, From}, {'$open', Secret, Filename, Modes}, #{ secret := Secret } = Data) ->
case raw_file_io:open(Filename, Modes) of
{ok, PrivateFd} ->
NextState = choose_decompression_state(PrivateFd),
NewData = Data#{ handle => PrivateFd },
{next_state, NextState, NewData, [{reply, From, ok}]};
Other ->
{stop_and_reply, normal, [{reply, From, Other}]}
end;
opening(_Event, _Contents, _Data) ->
{keep_state_and_data, [postpone]}.
internal_close(From, Data) ->
#{ handle := PrivateFd } = Data,
Response = ?CALL_FD(PrivateFd, close, []),
{stop_and_reply, normal, [{reply, From, Response}]}.
opened_passthrough(info, {'DOWN', Monitor, process, _Owner, _Reason}, #{ monitor := Monitor }) ->
{stop, shutdown};
opened_passthrough(info, _Message, _Data) ->
keep_state_and_data;
opened_passthrough({call, {Owner, _Tag} = From}, [close], #{ owner := Owner } = Data) ->
internal_close(From, Data);
opened_passthrough({call, {Owner, _Tag} = From}, [Method | Args], #{ owner := Owner } = Data) ->
#{ handle := PrivateFd } = Data,
Response = ?CALL_FD(PrivateFd, Method, Args),
{keep_state_and_data, [{reply, From, Response}]};
opened_passthrough({call, _From}, _Command, _Data) ->
%% The client functions filter this out, so we'll crash if the user does
%% anything stupid on purpose.
{shutdown, protocol_violation};
opened_passthrough(_Event, _Request, _Data) ->
keep_state_and_data.
%%
opened_gzip(info, {'DOWN', Monitor, process, _Owner, _Reason}, #{ monitor := Monitor }) ->
{stop, shutdown};
opened_gzip(info, _Message, _Data) ->
keep_state_and_data;
opened_gzip({call, {Owner, _Tag} = From}, [close], #{ owner := Owner } = Data) ->
internal_close(From, Data);
opened_gzip({call, {Owner, _Tag} = From}, [position, Mark], #{ owner := Owner } = Data) ->
case position(Data, Mark) of
{ok, NewData, Result} ->
Response = {ok, Result},
{keep_state, NewData, [{reply, From, Response}]};
Other ->
{keep_state_and_data, [{reply, From, Other}]}
end;
opened_gzip({call, {Owner, _Tag} = From}, [read, Size], #{ owner := Owner } = Data) ->
case read(Data, Size) of
{ok, NewData, Result} ->
Response = {ok, Result},
{keep_state, NewData, [{reply, From, Response}]};
Other ->
{keep_state_and_data, [{reply, From, Other}]}
end;
opened_gzip({call, {Owner, _Tag} = From}, [read_line], #{ owner := Owner } = Data) ->
case read_line(Data) of
{ok, NewData, Result} ->
Response = {ok, Result},
{keep_state, NewData, [{reply, From, Response}]};
Other ->
{keep_state_and_data, [{reply, From, Other}]}
end;
opened_gzip({call, {Owner, _Tag} = From}, [write, _IOData], #{ owner := Owner }) ->
Response = {error, ebadf},
{keep_state_and_data, [{reply, From, Response}]};
opened_gzip({call, {Owner, _Tag} = From}, _Request, #{ owner := Owner }) ->
Response = {error, enotsup},
{keep_state_and_data, [{reply, From, Response}]};
opened_gzip({call, _From}, _Request, _Data) ->
%% The client functions filter this out, so we'll crash if the user does
%% anything stupid on purpose.
{shutdown, protocol_violation};
opened_gzip(_Event, _Request, _Data) ->
keep_state_and_data.
%%
read(#{ buffer := Buffer } = Data, Size) ->
try read_1(Data, Buffer, prim_buffer:size(Buffer), Size) of
Result -> Result
catch
error:badarg -> {error, badarg};
error:_ -> {error, eio}
end.
read_1(Data, Buffer, BufferSize, ReadSize) when BufferSize >= ReadSize ->
#{ position := Position } = Data,
Decompressed = prim_buffer:read(Buffer, ReadSize),
{ok, Data#{ position => (Position + ReadSize) }, Decompressed};
read_1(Data, Buffer, BufferSize, ReadSize) when BufferSize < ReadSize ->
#{ handle := PrivateFd } = Data,
case ?CALL_FD(PrivateFd, read, [?INFLATE_CHUNK_SIZE]) of
{ok, Compressed} ->
#{ zlib := Z } = Data,
Uncompressed = erlang:iolist_to_iovec(zlib:inflate(Z, Compressed)),
prim_buffer:write(Buffer, Uncompressed),
read_1(Data, Buffer, prim_buffer:size(Buffer), ReadSize);
eof when BufferSize > 0 ->
read_1(Data, Buffer, BufferSize, BufferSize);
Other ->
Other
end.
read_line(#{ buffer := Buffer } = Data) ->
try read_line_1(Data, Buffer, prim_buffer:find_byte_index(Buffer, $\n)) of
{ok, NewData, Decompressed} -> {ok, NewData, Decompressed};
Other -> Other
catch
error:badarg -> {error, badarg};
error:_ -> {error, eio}
end.
read_line_1(Data, Buffer, not_found) ->
#{ handle := PrivateFd, zlib := Z } = Data,
case ?CALL_FD(PrivateFd, read, [?INFLATE_CHUNK_SIZE]) of
{ok, Compressed} ->
Uncompressed = erlang:iolist_to_iovec(zlib:inflate(Z, Compressed)),
prim_buffer:write(Buffer, Uncompressed),
read_line_1(Data, Buffer, prim_buffer:find_byte_index(Buffer, $\n));
eof ->
case prim_buffer:size(Buffer) of
Size when Size > 0 -> {ok, prim_buffer:read(Buffer, Size)};
Size when Size =:= 0 -> eof
end;
Error ->
Error
end;
read_line_1(Data, Buffer, {ok, LFIndex}) ->
%% Translate CRLF into just LF, completely ignoring which encoding is used,
%% but treat the file position as including CR.
#{ position := Position } = Data,
NewData = Data#{ position => (Position + LFIndex + 1) },
CRIndex = (LFIndex - 1),
TranslatedLine =
case prim_buffer:read(Buffer, LFIndex + 1) of
<<Line:CRIndex/binary, "\r\n">> -> <<Line/binary, "\n">>;
Line -> Line
end,
{ok, NewData, TranslatedLine}.
%%
%% We support seeking in both directions as long as it isn't relative to EOF.
%%
%% Seeking backwards is extremely inefficient since we have to seek to the very
%% beginning and then decompress up to the desired point.
%%
position(Data, Mark) when is_atom(Mark) ->
position(Data, {Mark, 0});
position(Data, Offset) when is_integer(Offset) ->
position(Data, {bof, Offset});
position(Data, {bof, Offset}) when is_integer(Offset) ->
position_1(Data, Offset);
position(Data, {cur, Offset}) when is_integer(Offset) ->
#{ position := Position } = Data,
position_1(Data, Position + Offset);
position(_Data, {eof, Offset}) when is_integer(Offset) ->
{error, einval};
position(_Data, _Other) ->
{error, badarg}.
position_1(_Data, Desired) when Desired < 0 ->
{error, einval};
position_1(#{ position := Desired } = Data, Desired) ->
{ok, Data, Desired};
position_1(#{ position := Current } = Data, Desired) when Current < Desired ->
case read(Data, min(Desired - Current, ?INFLATE_CHUNK_SIZE)) of
{ok, NewData, _Data} -> position_1(NewData, Desired);
eof -> {ok, Data, Current};
Other -> Other
end;
position_1(#{ position := Current } = Data, Desired) when Current > Desired ->
#{ handle := PrivateFd, buffer := Buffer, zlib := Z } = Data,
case ?CALL_FD(PrivateFd, position, [bof]) of
{ok, 0} ->
ok = zlib:inflateReset(Z),
prim_buffer:wipe(Buffer),
position_1(Data#{ position => 0 }, Desired);
Other ->
Other
end.
terminate(_Reason, _State, _Data) ->
ok.
