diff options
Diffstat (limited to 'lib/stdlib/src/filename.erl')
| -rw-r--r-- | lib/stdlib/src/filename.erl | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/lib/stdlib/src/filename.erl b/lib/stdlib/src/filename.erl index 9bf4290916..9a85642c17 100644 --- a/lib/stdlib/src/filename.erl +++ b/lib/stdlib/src/filename.erl @@ -34,6 +34,38 @@ %% we flatten the arguments immediately on function entry as that makes %% it easier to ensure that the code works. +%% +%% *** Requirements on Raw Filename Format *** +%% +%% These requirements are due to the 'filename' module +%% in stdlib. This since it is documented that it +%% should be able to operate on raw filenames as well +%% as ordinary filenames. +%% +%% A raw filename *must* be a byte sequence where: +%% 1. Codepoints 0-127 (7-bit ascii) *must* be encoded +%% as a byte with the corresponding value. That is, +%% the most significant bit in the byte encoding the +%% codepoint is never set. +%% 2. Codepoints greater than 127 *must* be encoded +%% with the most significant bit set in *every* byte +%% encoding it. +%% +%% Latin1 and UTF-8 meet these requirements while +%% UTF-16 and UTF-32 don't. +%% +%% On Windows filenames are natively stored as malformed +%% UTF-16LE (lonely surrogates may appear). A more correct +%% description than UTF-16 would be an array of 16-bit +%% words... In order to meet the requirements of the +%% raw file format we convert the malformed UTF-16LE to +%% malformed UTF-8 which meet the requirements. +%% +%% Note that these requirements are today only OTP +%% internal (erts-stdlib internal) requirements that +%% could be changed. +%% + -export([absname/1, absname/2, absname_join/2, basename/1, basename/2, dirname/1, extension/1, join/1, join/2, pathtype/1, @@ -41,6 +73,7 @@ safe_relative_path/1]). -export([find_src/1, find_src/2]). % deprecated -export([basedir/2, basedir/3]). +-export([validate/1]). %% Undocumented and unsupported exports. -export([append/2]). @@ -1135,3 +1168,72 @@ basedir_os_type() -> {win32,_} -> windows; _ -> linux end. + +%% +%% validate/1 +%% + +-spec validate(FileName) -> boolean() when + FileName :: file:name_all(). + +validate(FileName) when is_binary(FileName) -> + %% Raw filename... + validate_bin(FileName); +validate(FileName) when is_list(FileName); + is_atom(FileName) -> + validate_list(FileName, + file:native_name_encoding(), + os:type()). + +validate_list(FileName, Enc, Os) -> + try + true = validate_list(FileName, Enc, Os, 0) > 0 + catch + _ : _ -> false + end. + +validate_list([], _Enc, _Os, Chars) -> + Chars; +validate_list(C, Enc, Os, Chars) when is_integer(C) -> + validate_char(C, Enc, Os), + Chars+1; +validate_list(A, Enc, Os, Chars) when is_atom(A) -> + validate_list(atom_to_list(A), Enc, Os, Chars); +validate_list([H|T], Enc, Os, Chars) -> + NewChars = validate_list(H, Enc, Os, Chars), + validate_list(T, Enc, Os, NewChars). + +%% C is always an integer... +% validate_char(C, _, _) when not is_integer(C) -> +% throw(invalid); +validate_char(C, _, _) when C < 1 -> + throw(invalid); %% No negative or null characters... +validate_char(C, latin1, _) when C > 255 -> + throw(invalid); +validate_char(C, utf8, _) when C >= 16#110000 -> + throw(invalid); +validate_char(C, utf8, {win32, _}) when C > 16#ffff -> + throw(invalid); %% invalid win wchar... +validate_char(_C, utf8, {win32, _}) -> + ok; %% Range below is accepted on windows... +validate_char(C, utf8, _) when 16#D800 =< C, C =< 16#DFFF -> + throw(invalid); %% invalid unicode range... +validate_char(_, _, _) -> + ok. + +validate_bin(Bin) -> + %% Raw filename. That is, we do not interpret + %% the encoding, but we still do not accept + %% null characters... + try + true = validate_bin(Bin, 0) > 0 + catch + _ : _ -> false + end. + +validate_bin(<<>>, Bs) -> + Bs; +validate_bin(<<0, _Rest/binary>>, _Bs) -> + throw(invalid); %% No null characters allowed... +validate_bin(<<_B, Rest/binary>>, Bs) -> + validate_bin(Rest, Bs+1). |