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% 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.
-module(couch_util).
-export([start_driver/1]).
-export([should_flush/0, should_flush/1]).
-export([new_uuid/0, rand32/0, implode/2, collate/2, collate/3]).
-export([abs_pathname/1,abs_pathname/2, trim/1, ascii_lower/1]).
-export([encodeBase64/1, decodeBase64/1, to_hex/1]).
% arbitrarily chosen amount of memory to use before flushing to disk
-define(FLUSH_MAX_MEM, 10000000).
start_driver(LibDir) ->
% read config and register for configuration changes
case erl_ddll:load_driver(LibDir, "couch_erl_driver") of
ok ->
ok;
{error, already_loaded} ->
ok = erl_ddll:reload_driver(LibDir, "couch_erl_driver");
{error, Error} ->
exit(erl_ddll:format_error(Error))
end.
new_uuid() ->
to_hex(crypto:rand_bytes(16)).
to_hex([]) ->
[];
to_hex(Bin) when is_binary(Bin) ->
to_hex(binary_to_list(Bin));
to_hex([H|T]) ->
[to_digit(H div 16), to_digit(H rem 16) | to_hex(T)].
to_digit(N) when N < 10 -> $0 + N;
to_digit(N) -> $a + N-10.
% returns a random integer
rand32() ->
crypto:rand_uniform(0, 16#100000000).
% given a pathname "../foo/bar/" it gives back the fully qualified
% absolute pathname.
abs_pathname(" " ++ Filename) ->
% strip leading whitspace
abs_pathname(Filename);
abs_pathname([$/ |_]=Filename) ->
Filename;
abs_pathname(Filename) ->
{ok, Cwd} = file:get_cwd(),
{Filename2, Args} = separate_cmd_args(Filename, ""),
abs_pathname(Filename2, Cwd) ++ Args.
abs_pathname(Filename, Dir) ->
Name = filename:absname(Filename, Dir ++ "/"),
OutFilename = filename:join(fix_path_list(filename:split(Name), [])),
% If the filename is a dir (last char slash, put back end slash
case string:right(Filename,1) of
"/" ->
OutFilename ++ "/";
"\\" ->
OutFilename ++ "/";
_Else->
OutFilename
end.
% if this as an executable with arguments, seperate out the arguments
% ""./foo\ bar.sh -baz=blah" -> {"./foo\ bar.sh", " -baz=blah"}
separate_cmd_args("", CmdAcc) ->
{lists:reverse(CmdAcc), ""};
separate_cmd_args("\\ " ++ Rest, CmdAcc) -> % handle skipped value
separate_cmd_args(Rest, " \\" ++ CmdAcc);
separate_cmd_args(" " ++ Rest, CmdAcc) ->
{lists:reverse(CmdAcc), " " ++ Rest};
separate_cmd_args([Char|Rest], CmdAcc) ->
separate_cmd_args(Rest, [Char | CmdAcc]).
% lowercases string bytes that are the ascii characters A-Z.
% All other characters/bytes are ignored.
ascii_lower(String) ->
ascii_lower(String, []).
ascii_lower([], Acc) ->
lists:reverse(Acc);
ascii_lower([Char | RestString], Acc) when Char >= $A, Char =< $B ->
ascii_lower(RestString, [Char + ($a-$A) | Acc]);
ascii_lower([Char | RestString], Acc)->
ascii_lower(RestString, [Char | Acc]).
% Is a character whitespace?
is_whitespace($\s)-> true;
is_whitespace($\t)-> true;
is_whitespace($\n)-> true;
is_whitespace($\r)-> true;
is_whitespace(_Else) -> false.
% removes leading and trailing whitespace from a string
trim(String) ->
String2 = lists:dropwhile(fun is_whitespace/1, String),
lists:reverse(lists:dropwhile(fun is_whitespace/1, lists:reverse(String2))).
% takes a heirarchical list of dirs and removes the dots ".", double dots
% ".." and the corresponding parent dirs.
fix_path_list([], Acc) ->
lists:reverse(Acc);
fix_path_list([".."|Rest], [_PrevAcc|RestAcc]) ->
fix_path_list(Rest, RestAcc);
fix_path_list(["."|Rest], Acc) ->
fix_path_list(Rest, Acc);
fix_path_list([Dir | Rest], Acc) ->
fix_path_list(Rest, [Dir | Acc]).
implode(List, Sep) ->
implode(List, Sep, []).
implode([], _Sep, Acc) ->
lists:flatten(lists:reverse(Acc));
implode([H], Sep, Acc) ->
implode([], Sep, [H|Acc]);
implode([H|T], Sep, Acc) ->
implode(T, Sep, [Sep,H|Acc]).
drv_port() ->
case get(couch_drv_port) of
undefined ->
Port = open_port({spawn, "couch_erl_driver"}, []),
put(couch_drv_port, Port),
Port;
Port ->
Port
end.
collate(A, B) ->
collate(A, B, []).
collate(A, B, Options) when is_list(A), is_list(B) ->
Operation =
case lists:member(nocase, Options) of
true -> 1; % Case insensitive
false -> 0 % Case sensitive
end,
Port = drv_port(),
LenA = length(A),
LenB = length(B),
Bin = list_to_binary([<<LenA:32/native>>, A, <<LenB:32/native>>, B]),
case erlang:port_control(Port, Operation, Bin) of
[0] -> -1;
[1] -> 1;
[2] -> 0
end.
should_flush() ->
should_flush(?FLUSH_MAX_MEM).
should_flush(MemThreshHold) ->
case process_info(self(), memory) of
{memory, Mem} when Mem > 2*MemThreshHold ->
garbage_collect(),
case process_info(self(), memory) of
{memory, Mem} when Mem > MemThreshHold ->
true;
_ ->
false
end;
_ ->
false
end.
%%% Purpose : Base 64 encoding and decoding.
%%% Copied from ssl_base_64 to avoid using the
%%% erlang ssl library
-define(st(X,A), ((X-A+256) div 256)).
-define(CHARS, 64).
%% A PEM encoding consists of characters A-Z, a-z, 0-9, +, / and
%% =. Each character encodes a 6 bits value from 0 to 63 (A = 0, / =
%% 63); = is a padding character.
%%
%%
%% encode64(Bytes|Binary) -> Chars
%%
%% Take 3 bytes a time (3 x 8 = 24 bits), and make 4 characters out of
%% them (4 x 6 = 24 bits).
%%
encodeBase64(Bs) when list(Bs) ->
encodeBase64(list_to_binary(Bs));
encodeBase64(<<B:3/binary, Bs/binary>>) ->
<<C1:6, C2:6, C3:6, C4:6>> = B,
[enc(C1), enc(C2), enc(C3), enc(C4)| encodeBase64(Bs)];
encodeBase64(<<B:2/binary>>) ->
<<C1:6, C2:6, C3:6, _:6>> = <<B/binary, 0>>,
[enc(C1), enc(C2), enc(C3), $=];
encodeBase64(<<B:1/binary>>) ->
<<C1:6, C2:6, _:12>> = <<B/binary, 0, 0>>,
[enc(C1), enc(C2), $=, $=];
encodeBase64(<<>>) ->
[].
%%
%% decodeBase64(Chars) -> Binary
%%
decodeBase64(Cs) ->
list_to_binary(decode1(Cs)).
decode1([C1, C2, $=, $=]) ->
<<B1, _:16>> = <<(dec(C1)):6, (dec(C2)):6, 0:12>>,
[B1];
decode1([C1, C2, C3, $=]) ->
<<B1, B2, _:8>> = <<(dec(C1)):6, (dec(C2)):6, (dec(C3)):6, (dec(0)):6>>,
[B1, B2];
decode1([C1, C2, C3, C4| Cs]) ->
Bin = <<(dec(C1)):6, (dec(C2)):6, (dec(C3)):6, (dec(C4)):6>>,
[Bin| decode1(Cs)];
decode1([]) ->
[].
%% enc/1 and dec/1
%%
%% Mapping: 0-25 -> A-Z, 26-51 -> a-z, 52-61 -> 0-9, 62 -> +, 63 -> /
%%
enc(C) ->
65 + C + 6*?st(C,26) - 75*?st(C,52) -15*?st(C,62) + 3*?st(C,63).
dec(C) ->
62*?st(C,43) + ?st(C,47) + (C-59)*?st(C,48) - 69*?st(C,65) - 6*?st(C,97).
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