1 files changed, 261 insertions, 0 deletions
diff --git a/lib/kernel/src/raw_file_io_inflate.erl b/lib/kernel/src/raw_file_io_inflate.erl
new file mode 100644
index 0000000000..7e9780310c
--- /dev/null
+++ b/lib/kernel/src/raw_file_io_inflate.erl
@@ -0,0 +1,261 @@
+%%
+%% %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.