aboutsummaryrefslogtreecommitdiffstats
path: root/lib/kernel/src/raw_file_io_inflate.erl
blob: 7e9780310cf5669e69e6f81126fe0d7f0d622ccf (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
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.