File 4241-base64-Add-selectable-alphabet.patch of Package erlang

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File 4241-base64-Add-selectable-alphabet.patch of Package erlang (Revision 3e53aa07e56d6cc0c5ffbbfd2f14b043)

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From 05e61dc7eb568cc5a5db965dcc3534fb6c9aa66d Mon Sep 17 00:00:00 2001
From: Jan Uhlig <juhlig@hnc-agency.org>
Date: Thu, 15 Sep 2022 12:28:33 +0200
Subject: [PATCH] base64: Add selectable alphabet

RFC 4648 defines two possible alphabets that may be used for
encoding and decoding, the standard alphabet in Section 4 and
an alternative URL and Filename safe alphabet in Section 5.

This commit adds the ability to specify one of the alphabets
for encoding and decoding.

Co-authored-by: Maria Scott <maria-12648430@hnc-agency.org>
---
 lib/stdlib/doc/src/base64.xml | 85 ++-
 lib/stdlib/src/base64.erl | 658 ++++++++++--------
 lib/stdlib/test/base64_SUITE.erl | 98 ++-
 .../test/base64_property_test_SUITE.erl | 108 ++-
 lib/stdlib/test/property_test/base64_prop.erl | 375 ++++++----
 5 files changed, 856 insertions(+), 468 deletions(-)

diff --git a/lib/stdlib/doc/src/base64.xml b/lib/stdlib/doc/src/base64.xml
index bb45927c3f..b58e7394f2 100644
--- a/lib/stdlib/doc/src/base64.xml
+++ b/lib/stdlib/doc/src/base64.xml
@@ -40,7 +40,17 @@
 <datatypes>
 <datatype>
 <name name="base64_alphabet"/>
- <desc>Base 64 Encoding alphabet, see <url href="https://www.ietf.org/rfc/rfc4648.txt">RFC 4648</url>.
+ <desc>Base 64 Encoding alphabet, see
+ <url href="https://datatracker.ietf.org/doc/html/rfc4648">RFC 4648</url>.
+ </desc>
+ </datatype>
+ <datatype>
+ <name name="base64_mode"/>
+ <desc>
+ Selector for the Base 64 Encoding alphabet used for encoding and decoding,
+ see <url href="https://datatracker.ietf.org/doc/html/rfc4648">RFC 4648</url>
+ Sections <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-4">4</url>
+ and <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-5">5</url>.
 </desc>
 </datatype>
 <datatype>
@@ -67,18 +77,54 @@
 <name name="mime_decode" arity="1" since=""/>
 <name name="mime_decode_to_string" arity="1" since=""/>
 <fsummary>Decode a base64 encoded string to data.</fsummary>
- <type variable="Base64" name_i="1"/>
+ <type variable="Base64"/>
 <type variable="Data" name_i="1"/>
 <type variable="DataString" name_i="2"/>
 <desc>
- Decodes a base64-encoded string to plain ASCII. See
- <url href="https://www.ietf.org/html/rfc4648">RFC 4648</url>.
+ Decodes a base64 string encoded using the standard alphabet according
+ to <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-4">RFC 4648
+ Section 4</url> to plain ASCII.
 <c>mime_decode/1</c> and <c>mime_decode_to_string/1</c> strip away
 illegal characters, while <c>decode/1</c> and
 <c>decode_to_string/1</c> only strip away whitespace characters.
 </desc>
 </func>
 
+ <func>
+ <name name="decode" arity="2" since="OTP 25.1"/>
+ <name name="decode_to_string" arity="2" since="OTP 25.1"/>
+ <name name="mime_decode" arity="2" since="OTP 25.1"/>
+ <name name="mime_decode_to_string" arity="2" since="OTP 25.1"/>
+ <fsummary>Decode a base64 encoded string to data.</fsummary>
+ <type variable="Base64"/>
+ <type variable="Mode" name_i="1"/>
+ <type variable="Data" name_i="1"/>
+ <type variable="DataString" name_i="2"/>
+ <desc>
+ Decodes a base64 string encoded using the alphabet indicated by the
+ <c><anno>Mode</anno></c> parameter to plain ASCII.
+ <c>mime_decode/2</c> and <c>mime_decode_to_string/2</c> strip away
+ illegal characters, while <c>decode/2</c> and
+ <c>decode_to_string/2</c> only strip away whitespace characters.
+ The <c><anno>Mode</anno></c> parameter can be one of the following:
+ <taglist>
+ <tag><c>standard</c></tag>
+ <item>Decode the given string using the standard base64 alphabet according
+ to <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-4">RFC 4648
+ Section 4</url>, that is <c>"+"</c> and <c>"/"</c> are representing bytes <c>62</c>
+ and <c>63</c> respectively, while <c>"-"</c> and <c>"_"</c> are illegal
+ characters.</item>
+ <tag><c>urlsafe</c></tag>
+ <item>Decode the given string using the alternative "URL and Filename safe" base64
+ alphabet according to
+ <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-5">RFC 4648
+ Section 5</url>, that is <c>"-"</c> and <c>"_"</c> are representing bytes <c>62</c>
+ and <c>63</c> respectively, while <c>"+"</c> and <c>"/"</c> are illegal
+ characters.</item>
+ </taglist>
+ </desc>
+ </func>
+
 <func>
 <name name="encode" arity="1" since=""/>
 <name name="encode_to_string" arity="1" since=""/>
@@ -87,8 +133,35 @@
 <type variable="Base64" name_i="1"/>
 <type variable="Base64String"/>
 <desc>
- Encodes a plain ASCII string into base64. The result is 33% larger
- than the data.
+ Encodes a plain ASCII string into base64 using the standard alphabet
+ according to <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-4">RFC 4648
+ Section 4</url>. The result is 33% larger than the data.
+ </desc>
+ </func>
+
+ <func>
+ <name name="encode" arity="2" since="OTP 25.1"/>
+ <name name="encode_to_string" arity="2" since="OTP 25.1"/>
+ <fsummary>Encode data into base64.</fsummary>
+ <type variable="Data"/>
+ <type variable="Mode"/>
+ <type variable="Base64" name_i="1"/>
+ <type variable="Base64String"/>
+ <desc>
+ Encodes a plain ASCII string into base64 using the alphabet indicated by
+ the <c><anno>Mode</anno></c> parameter. The result is 33% larger than the data.
+ The <c><anno>Mode</anno></c> parameter can be one of the following:
+ <taglist>
+ <tag><c>standard</c></tag>
+ <item>Encode the given string using the standard base64 alphabet according
+ to <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-4">RFC 4648
+ Section 4</url>.</item>
+ <tag><c>urlsafe</c></tag>
+ <item>Encode the given string using the alternative "URL and Filename safe" base64
+ alphabet according to
+ <url href="https://datatracker.ietf.org/doc/html/rfc4648#section-5">RFC 4648
+ Section 5</url>.</item>
+ </taglist>
 </desc>
 </func>
 </funcs>
diff --git a/lib/stdlib/src/base64.erl b/lib/stdlib/src/base64.erl
index 600f73a4cb..eae9527a2d 100644
--- a/lib/stdlib/src/base64.erl
+++ b/lib/stdlib/src/base64.erl
@@ -21,12 +21,19 @@
 
 -module(base64).
 
--export([encode/1, decode/1, mime_decode/1,
-	 encode_to_string/1, decode_to_string/1, mime_decode_to_string/1]).
-
+-export([encode/1, encode/2,
+	 decode/1, decode/2,
+	 mime_decode/1, mime_decode/2,
+	 encode_to_string/1, encode_to_string/2,
+	 decode_to_string/1, decode_to_string/2,
+	 mime_decode_to_string/1, mime_decode_to_string/2]).
 
 %% RFC 4648: Base 64 Encoding alphabet
--type base64_alphabet() :: $A..$Z | $a..$z | $0..$9 | $+ | $/ | $=.
+-type base64_alphabet() :: $A..$Z | $a..$z | $0..$9 | $+ | $/ | $- | $_ | $=.
+
+%% Selector for the Base 64 alphabet, `standard' for RFC 4648
+%% Section 4, `urlsafe' for RFC 4648 Section 5.
+-type base64_mode() :: 'standard' | 'urlsafe'.
 
 %% The following type is a subtype of string() for return values
 %% of encoding functions.
@@ -40,76 +47,95 @@
 Data :: byte_string() | binary(),
 Base64String :: base64_string().
 
-encode_to_string(Bin) when is_binary(Bin) ->
- encode_to_string(binary_to_list(Bin));
-encode_to_string(List) when is_list(List) ->
- encode_list_to_string(List).
+encode_to_string(Data) ->
+ encode_to_string(Data, standard).
+
+-spec encode_to_string(Data, Mode) -> Base64String when
+ Data :: byte_string() | binary(),
+ Mode :: base64_mode(),
+ Base64String :: base64_string().
+
+encode_to_string(Bin, Mode) when is_binary(Bin) ->
+ encode_to_string(binary_to_list(Bin), Mode);
+encode_to_string(List, Mode) when is_list(List) ->
+ encode_list_to_string(get_encoding_offset(Mode), List).
 
 -spec encode(Data) -> Base64 when
 Data :: byte_string() | binary(),
 Base64 :: base64_binary().
 
-encode(Bin) when is_binary(Bin) ->
- encode_binary(Bin, <<>>);
-encode(List) when is_list(List) ->
- encode_list(List, <<>>).
+encode(Data) ->
+ encode(Data, standard).
 
-encode_list_to_string([]) ->
+-spec encode(Data, Mode) -> Base64 when
+ Data :: byte_string() | binary(),
+ Mode :: base64_mode(),
+ Base64 :: base64_binary().
+
+encode(Bin, Mode) when is_binary(Bin) ->
+ encode_binary(get_encoding_offset(Mode), Bin, <<>>);
+encode(List, Mode) when is_list(List) ->
+ encode_list(get_encoding_offset(Mode), List, <<>>).
+
+encode_list_to_string(_ModeOffset, []) ->
 [];
-encode_list_to_string([B1]) ->
- [b64e(B1 bsr 2),
- b64e((B1 band 3) bsl 4), $=, $=];
-encode_list_to_string([B1,B2]) ->
- [b64e(B1 bsr 2),
- b64e(((B1 band 3) bsl 4) bor (B2 bsr 4)),
- b64e((B2 band 15) bsl 2), $=];
-encode_list_to_string([B1,B2,B3|Ls]) ->
+encode_list_to_string(ModeOffset, [B1]) ->
+ [b64e(B1 bsr 2, ModeOffset),
+ b64e((B1 band 3) bsl 4, ModeOffset), $=, $=];
+encode_list_to_string(ModeOffset, [B1,B2]) ->
+ [b64e(B1 bsr 2, ModeOffset),
+ b64e(((B1 band 3) bsl 4) bor (B2 bsr 4), ModeOffset),
+ b64e((B2 band 15) bsl 2, ModeOffset), $=];
+encode_list_to_string(ModeOffset, [B1,B2,B3|Ls]) ->
 BB = (B1 bsl 16) bor (B2 bsl 8) bor B3,
- [b64e(BB bsr 18),
- b64e((BB bsr 12) band 63), 
- b64e((BB bsr 6) band 63),
- b64e(BB band 63) | encode_list_to_string(Ls)].
-
-encode_binary(<<B1:6, B2:6, B3:6, B4:6, B5:6, B6:6, B7:6, B8:6, Ls/bits>>, A) ->
- encode_binary(Ls,
+ [b64e(BB bsr 18, ModeOffset),
+ b64e((BB bsr 12) band 63, ModeOffset), 
+ b64e((BB bsr 6) band 63, ModeOffset),
+ b64e(BB band 63, ModeOffset) | encode_list_to_string(ModeOffset, Ls)].
+
+encode_binary(ModeOffset, <<B1:6, B2:6, B3:6, B4:6, B5:6, B6:6, B7:6, B8:6, Ls/bits>>, A) ->
+ encode_binary(ModeOffset,
+ Ls,
 <<A/bits,
- (b64e(B1)):8,
- (b64e(B2)):8,
- (b64e(B3)):8,
- (b64e(B4)):8,
- (b64e(B5)):8,
- (b64e(B6)):8,
- (b64e(B7)):8,
- (b64e(B8)):8>>);
-encode_binary(<<>>, A) ->
+ (b64e(B1, ModeOffset)):8,
+ (b64e(B2, ModeOffset)):8,
+ (b64e(B3, ModeOffset)):8,
+ (b64e(B4, ModeOffset)):8,
+ (b64e(B5, ModeOffset)):8,
+ (b64e(B6, ModeOffset)):8,
+ (b64e(B7, ModeOffset)):8,
+ (b64e(B8, ModeOffset)):8>>);
+encode_binary(_ModeOffset, <<>>, A) ->
 A;
-encode_binary(<<B1:6, B2:6, B3:6, B4:6, Ls/bits>>, A) ->
- encode_binary(Ls,
+encode_binary(ModeOffset, <<B1:6, B2:6, B3:6, B4:6, Ls/bits>>, A) ->
+ encode_binary(ModeOffset,
+		 Ls,
 <<A/bits,
- (b64e(B1)):8,
- (b64e(B2)):8,
- (b64e(B3)):8,
- (b64e(B4)):8>>);
-encode_binary(<<B1:6, B2:2>>, A) ->
- <<A/bits,(b64e(B1)):8,(b64e(B2 bsl 4)):8,$=:8,$=:8>>;
-encode_binary(<<B1:6, B2:6, B3:4>>, A) ->
- <<A/bits,(b64e(B1)):8,(b64e(B2)):8,(b64e(B3 bsl 2)):8, $=:8>>.
-
-encode_list([], A) ->
+ (b64e(B1, ModeOffset)):8,
+ (b64e(B2, ModeOffset)):8,
+ (b64e(B3, ModeOffset)):8,
+ (b64e(B4, ModeOffset)):8>>);
+encode_binary(ModeOffset, <<B1:6, B2:2>>, A) ->
+ <<A/bits,(b64e(B1, ModeOffset)):8,(b64e(B2 bsl 4, ModeOffset)):8,$=:8,$=:8>>;
+encode_binary(ModeOffset, <<B1:6, B2:6, B3:4>>, A) ->
+ <<A/bits,(b64e(B1, ModeOffset)):8,(b64e(B2, ModeOffset)):8,(b64e(B3 bsl 2, ModeOffset)):8, $=:8>>.
+
+encode_list(_ModeOffset, [], A) ->
 A;
-encode_list([B1], A) ->
- <<A/bits,(b64e(B1 bsr 2)):8,(b64e((B1 band 3) bsl 4)):8,$=:8,$=:8>>;
-encode_list([B1,B2], A) ->
- <<A/bits,(b64e(B1 bsr 2)):8,
- (b64e(((B1 band 3) bsl 4) bor (B2 bsr 4))):8,
- (b64e((B2 band 15) bsl 2)):8, $=:8>>;
-encode_list([B1,B2,B3|Ls], A) ->
+encode_list(ModeOffset, [B1], A) ->
+ <<A/bits,(b64e(B1 bsr 2, ModeOffset)):8,(b64e((B1 band 3) bsl 4, ModeOffset)):8,$=:8,$=:8>>;
+encode_list(ModeOffset, [B1,B2], A) ->
+ <<A/bits,(b64e(B1 bsr 2, ModeOffset)):8,
+ (b64e(((B1 band 3) bsl 4) bor (B2 bsr 4), ModeOffset)):8,
+ (b64e((B2 band 15) bsl 2, ModeOffset)):8, $=:8>>;
+encode_list(ModeOffset, [B1,B2,B3|Ls], A) ->
 BB = (B1 bsl 16) bor (B2 bsl 8) bor B3,
- encode_list(Ls,
- <<A/bits,(b64e(BB bsr 18)):8,
- (b64e((BB bsr 12) band 63)):8,
- (b64e((BB bsr 6) band 63)):8,
- (b64e(BB band 63)):8>>).
+ encode_list(ModeOffset,
+		Ls,
+ <<A/bits,(b64e(BB bsr 18, ModeOffset)):8,
+ (b64e((BB bsr 12) band 63, ModeOffset)):8,
+ (b64e((BB bsr 6) band 63, ModeOffset)):8,
+ (b64e(BB band 63, ModeOffset)):8>>).
 
 %% mime_decode strips away all characters not Base64 before
 %% converting, whereas decode crashes if an illegal character is found
@@ -118,19 +144,35 @@ encode_list([B1,B2,B3|Ls], A) ->
 Base64 :: base64_string() | base64_binary(),
 Data :: binary().
 
-decode(Bin) when is_binary(Bin) ->
- decode_binary(Bin, <<>>);
-decode(List) when is_list(List) ->
- decode_list(List, <<>>).
+decode(Base64) ->
+ decode(Base64, standard).
+
+-spec decode(Base64, Mode) -> Data when
+ Base64 :: base64_string() | base64_binary(),
+ Mode :: base64_mode(),
+ Data :: binary().
+
+decode(Bin, Mode) when is_binary(Bin) ->
+ decode_binary(get_decoding_offset(Mode), Bin, <<>>);
+decode(List, Mode) when is_list(List) ->
+ decode_list(get_decoding_offset(Mode), List, <<>>).
 
 -spec mime_decode(Base64) -> Data when
 Base64 :: base64_string() | base64_binary(),
 Data :: binary().
 
-mime_decode(Bin) when is_binary(Bin) ->
- mime_decode_binary(Bin, <<>>);
-mime_decode(List) when is_list(List) ->
- mime_decode_list(List, <<>>).
+mime_decode(Base64) ->
+ mime_decode(Base64, standard).
+
+-spec mime_decode(Base64, Mode) -> Data when
+ Base64 :: base64_string() | base64_binary(),
+ Mode :: base64_mode(),
+ Data :: binary().
+
+mime_decode(Bin, Mode) when is_binary(Bin) ->
+ mime_decode_binary(get_decoding_offset(Mode), Bin, <<>>);
+mime_decode(List, Mode) when is_list(List) ->
+ mime_decode_list(get_decoding_offset(Mode), List, <<>>).
 
 %% mime_decode_to_string strips away all characters not Base64 before
 %% converting, whereas decode_to_string crashes if an illegal
@@ -140,352 +182,338 @@ mime_decode(List) when is_list(List) ->
 Base64 :: base64_string() | base64_binary(),
 DataString :: byte_string().
 
-decode_to_string(Bin) when is_binary(Bin) ->
- decode_to_string(binary_to_list(Bin));
-decode_to_string(List) when is_list(List) ->
- decode_list_to_string(List).
+decode_to_string(Base64) ->
+ decode_to_string(Base64, standard).
+
+-spec decode_to_string(Base64, Mode) -> DataString when
+ Base64 :: base64_string() | base64_binary(),
+ Mode :: base64_mode(),
+ DataString :: byte_string().
+
+decode_to_string(Bin, Mode) when is_binary(Bin) ->
+ decode_to_string(binary_to_list(Bin), Mode);
+decode_to_string(List, Mode) when is_list(List) ->
+ decode_list_to_string(get_decoding_offset(Mode), List).
 
 -spec mime_decode_to_string(Base64) -> DataString when
 Base64 :: base64_string() | base64_binary(),
 DataString :: byte_string().
 
-mime_decode_to_string(Bin) when is_binary(Bin) ->
- mime_decode_to_string(binary_to_list(Bin));
-mime_decode_to_string(List) when is_list(List) ->
- mime_decode_list_to_string(List).
+mime_decode_to_string(Base64) ->
+ mime_decode_to_string(Base64, standard).
+
+-spec mime_decode_to_string(Base64, Mode) -> DataString when
+ Base64 :: base64_string() | base64_binary(),
+ Mode :: base64_mode(),
+ DataString :: byte_string().
+
+mime_decode_to_string(Bin, Mode) when is_binary(Bin) ->
+ mime_decode_to_string(binary_to_list(Bin), Mode);
+mime_decode_to_string(List, Mode) when is_list(List) ->
+ mime_decode_list_to_string(get_decoding_offset(Mode), List).
 
 %% Skipping pad character if not at end of string. Also liberal about
 %% excess padding and skipping of other illegal (non-base64 alphabet)
 %% characters. See section 3.3 of RFC4648
-mime_decode_list([0 | Cs], A) ->
- mime_decode_list(Cs, A);
-mime_decode_list([C1 | Cs], A) ->
- case b64d(C1) of
- B1 when is_integer(B1) -> mime_decode_list(Cs, A, B1);
- _ -> mime_decode_list(Cs, A) % eq is padding
+mime_decode_list(ModeOffset, [C1 | Cs], A) ->
+ case b64d(C1, ModeOffset) of
+ B1 when is_integer(B1) -> mime_decode_list(ModeOffset, Cs, A, B1);
+ _ -> mime_decode_list(ModeOffset, Cs, A) % eq is padding
 end;
-mime_decode_list([], A) ->
+mime_decode_list(_ModeOffset, [], A) ->
 A.
 
-mime_decode_list([0 | Cs], A, B1) ->
- mime_decode_list(Cs, A, B1);
-mime_decode_list([C2 | Cs], A, B1) ->
- case b64d(C2) of
+mime_decode_list(ModeOffset, [C2 | Cs], A, B1) ->
+ case b64d(C2, ModeOffset) of
 B2 when is_integer(B2) ->
- mime_decode_list(Cs, A, B1, B2);
- _ -> mime_decode_list(Cs, A, B1) % eq is padding
+ mime_decode_list(ModeOffset, Cs, A, B1, B2);
+ _ -> mime_decode_list(ModeOffset, Cs, A, B1) % eq is padding
 end.
 
-mime_decode_list([0 | Cs], A, B1, B2) ->
- mime_decode_list(Cs, A, B1, B2);
-mime_decode_list([C3 | Cs], A, B1, B2) ->
- case b64d(C3) of
+mime_decode_list(ModeOffset, [C3 | Cs], A, B1, B2) ->
+ case b64d(C3, ModeOffset) of
 B3 when is_integer(B3) ->
- mime_decode_list(Cs, A, B1, B2, B3);
+ mime_decode_list(ModeOffset, Cs, A, B1, B2, B3);
 eq=B3 ->
- mime_decode_list_after_eq(Cs, A, B1, B2, B3);
- _ -> mime_decode_list(Cs, A, B1, B2)
+ mime_decode_list_after_eq(ModeOffset, Cs, A, B1, B2, B3);
+ _ -> mime_decode_list(ModeOffset, Cs, A, B1, B2)
 end.
 
-mime_decode_list([0 | Cs], A, B1, B2, B3) ->
- mime_decode_list(Cs, A, B1, B2, B3);
-mime_decode_list([C4 | Cs], A, B1, B2, B3) ->
- case b64d(C4) of
+mime_decode_list(ModeOffset, [C4 | Cs], A, B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
 B4 when is_integer(B4) ->
- mime_decode_list(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
+ mime_decode_list(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
 eq ->
- mime_decode_list_after_eq(Cs, A, B1, B2, B3);
- _ -> mime_decode_list(Cs, A, B1, B2, B3)
+ mime_decode_list_after_eq(ModeOffset, Cs, A, B1, B2, B3);
+ _ -> mime_decode_list(ModeOffset, Cs, A, B1, B2, B3)
 end.
 
-mime_decode_list_after_eq([0 | Cs], A, B1, B2, B3) ->
- mime_decode_list_after_eq(Cs, A, B1, B2, B3);
-mime_decode_list_after_eq([C | Cs], A, B1, B2, B3) ->
- case b64d(C) of
+mime_decode_list_after_eq(ModeOffset, [C | Cs], A, B1, B2, B3) ->
+ case b64d(C, ModeOffset) of
 B when is_integer(B) ->
 %% More valid data, skip the eq as invalid
 case B3 of
- eq -> mime_decode_list(Cs, A, B1, B2, B);
- _ -> mime_decode_list(Cs, <<A/bits,B1:6,B2:6,B3:6,B:6>>)
+ eq -> mime_decode_list(ModeOffset, Cs, A, B1, B2, B);
+ _ -> mime_decode_list(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B:6>>)
 end;
- _ -> mime_decode_list_after_eq(Cs, A, B1, B2, B3)
+ _ -> mime_decode_list_after_eq(ModeOffset, Cs, A, B1, B2, B3)
 end;
-mime_decode_list_after_eq([], A, B1, B2, eq) ->
+mime_decode_list_after_eq(_ModeOffset, [], A, B1, B2, eq) ->
 <<A/bits,B1:6,(B2 bsr 4):2>>;
-mime_decode_list_after_eq([], A, B1, B2, B3) ->
+mime_decode_list_after_eq(_ModeOffset, [], A, B1, B2, B3) ->
 <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>.
 
-mime_decode_binary(<<0:8, Cs/bits>>, A) ->
- mime_decode_binary(Cs, A);
-mime_decode_binary(<<C1:8, Cs/bits>>, A) ->
- case b64d(C1) of
- B1 when is_integer(B1) -> mime_decode_binary(Cs, A, B1);
- _ -> mime_decode_binary(Cs, A) % eq is padding
+mime_decode_binary(ModeOffset, <<C1:8, Cs/bits>>, A) ->
+ case b64d(C1, ModeOffset) of
+ B1 when is_integer(B1) -> mime_decode_binary(ModeOffset, Cs, A, B1);
+ _ -> mime_decode_binary(ModeOffset, Cs, A) % eq is padding
 end;
-mime_decode_binary(<<>>, A) ->
+mime_decode_binary(_ModeOffset, <<>>, A) ->
 A.
 
-mime_decode_binary(<<0:8, Cs/bits>>, A, B1) ->
- mime_decode_binary(Cs, A, B1);
-mime_decode_binary(<<C2:8, Cs/bits>>, A, B1) ->
- case b64d(C2) of
+mime_decode_binary(ModeOffset, <<C2:8, Cs/bits>>, A, B1) ->
+ case b64d(C2, ModeOffset) of
 B2 when is_integer(B2) ->
- mime_decode_binary(Cs, A, B1, B2);
- _ -> mime_decode_binary(Cs, A, B1) % eq is padding
+ mime_decode_binary(ModeOffset, Cs, A, B1, B2);
+ _ -> mime_decode_binary(ModeOffset, Cs, A, B1) % eq is padding
 end.
 
-mime_decode_binary(<<0:8, Cs/bits>>, A, B1, B2) ->
- mime_decode_binary(Cs, A, B1, B2);
-mime_decode_binary(<<C3:8, Cs/bits>>, A, B1, B2) ->
- case b64d(C3) of
+mime_decode_binary(ModeOffset, <<C3:8, Cs/bits>>, A, B1, B2) ->
+ case b64d(C3, ModeOffset) of
 B3 when is_integer(B3) ->
- mime_decode_binary(Cs, A, B1, B2, B3);
+ mime_decode_binary(ModeOffset, Cs, A, B1, B2, B3);
 eq=B3 ->
- mime_decode_binary_after_eq(Cs, A, B1, B2, B3);
- _ -> mime_decode_binary(Cs, A, B1, B2)
+ mime_decode_binary_after_eq(ModeOffset, Cs, A, B1, B2, B3);
+ _ -> mime_decode_binary(ModeOffset, Cs, A, B1, B2)
 end.
 
-mime_decode_binary(<<0:8, Cs/bits>>, A, B1, B2, B3) ->
- mime_decode_binary(Cs, A, B1, B2, B3);
-mime_decode_binary(<<C4:8, Cs/bits>>, A, B1, B2, B3) ->
- case b64d(C4) of
+mime_decode_binary(ModeOffset, <<C4:8, Cs/bits>>, A, B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
 B4 when is_integer(B4) ->
- mime_decode_binary(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
+ mime_decode_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
 eq ->
- mime_decode_binary_after_eq(Cs, A, B1, B2, B3);
- _ -> mime_decode_binary(Cs, A, B1, B2, B3)
+ mime_decode_binary_after_eq(ModeOffset, Cs, A, B1, B2, B3);
+ _ -> mime_decode_binary(ModeOffset, Cs, A, B1, B2, B3)
 end.
 
-mime_decode_binary_after_eq(<<0:8, Cs/bits>>, A, B1, B2, B3) ->
- mime_decode_binary_after_eq(Cs, A, B1, B2, B3);
-mime_decode_binary_after_eq(<<C:8, Cs/bits>>, A, B1, B2, B3) ->
- case b64d(C) of
+mime_decode_binary_after_eq(ModeOffset, <<C:8, Cs/bits>>, A, B1, B2, B3) ->
+ case b64d(C, ModeOffset) of
 B when is_integer(B) ->
 %% More valid data, skip the eq as invalid
 case B3 of
- eq -> mime_decode_binary(Cs, A, B1, B2, B);
- _ -> mime_decode_binary(Cs, <<A/bits,B1:6,B2:6,B3:6,B:6>>)
+ eq -> mime_decode_binary(ModeOffset, Cs, A, B1, B2, B);
+ _ -> mime_decode_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B:6>>)
 end;
- _ -> mime_decode_binary_after_eq(Cs, A, B1, B2, B3)
+ _ -> mime_decode_binary_after_eq(ModeOffset, Cs, A, B1, B2, B3)
 end;
-mime_decode_binary_after_eq(<<>>, A, B1, B2, eq) ->
+mime_decode_binary_after_eq(_ModeOffset, <<>>, A, B1, B2, eq) ->
 <<A/bits,B1:6,(B2 bsr 4):2>>;
-mime_decode_binary_after_eq(<<>>, A, B1, B2, B3) ->
+mime_decode_binary_after_eq(_ModeOffset, <<>>, A, B1, B2, B3) ->
 <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>.
 
-mime_decode_list_to_string([0 | Cs]) ->
- mime_decode_list_to_string(Cs);
-mime_decode_list_to_string([C1 | Cs]) ->
- case b64d(C1) of
- B1 when is_integer(B1) -> mime_decode_list_to_string(Cs, B1);
- _ -> mime_decode_list_to_string(Cs) % eq is padding
+mime_decode_list_to_string(ModeOffset, [C1 | Cs]) ->
+ case b64d(C1, ModeOffset) of
+ B1 when is_integer(B1) -> mime_decode_list_to_string(ModeOffset, Cs, B1);
+ _ -> mime_decode_list_to_string(ModeOffset, Cs) % eq is padding
 end;
-mime_decode_list_to_string([]) ->
+mime_decode_list_to_string(_ModeOffset, []) ->
 [].
 
-mime_decode_list_to_string([0 | Cs], B1) ->
- mime_decode_list_to_string(Cs, B1);
-mime_decode_list_to_string([C2 | Cs], B1) ->
- case b64d(C2) of
+mime_decode_list_to_string(ModeOffset, [C2 | Cs], B1) ->
+ case b64d(C2, ModeOffset) of
 B2 when is_integer(B2) ->
- mime_decode_list_to_string(Cs, B1, B2);
- _ -> mime_decode_list_to_string(Cs, B1) % eq is padding
+ mime_decode_list_to_string(ModeOffset, Cs, B1, B2);
+ _ -> mime_decode_list_to_string(ModeOffset, Cs, B1) % eq is padding
 end.
 
-mime_decode_list_to_string([0 | Cs], B1, B2) ->
- mime_decode_list_to_string(Cs, B1, B2);
-mime_decode_list_to_string([C3 | Cs], B1, B2) ->
- case b64d(C3) of
+mime_decode_list_to_string(ModeOffset, [C3 | Cs], B1, B2) ->
+ case b64d(C3, ModeOffset) of
 B3 when is_integer(B3) ->
- mime_decode_list_to_string(Cs, B1, B2, B3);
- eq=B3 -> mime_decode_list_to_string_after_eq(Cs, B1, B2, B3);
- _ -> mime_decode_list_to_string(Cs, B1, B2)
+ mime_decode_list_to_string(ModeOffset, Cs, B1, B2, B3);
+ eq=B3 -> mime_decode_list_to_string_after_eq(ModeOffset, Cs, B1, B2, B3);
+ _ -> mime_decode_list_to_string(ModeOffset, Cs, B1, B2)
 end.
 
-mime_decode_list_to_string([0 | Cs], B1, B2, B3) ->
- mime_decode_list_to_string(Cs, B1, B2, B3);
-mime_decode_list_to_string([C4 | Cs], B1, B2, B3) ->
- case b64d(C4) of
+mime_decode_list_to_string(ModeOffset, [C4 | Cs], B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
 B4 when is_integer(B4) ->
 Bits4x6 = (B1 bsl 18) bor (B2 bsl 12) bor (B3 bsl 6) bor B4,
 Octet1 = Bits4x6 bsr 16,
 Octet2 = (Bits4x6 bsr 8) band 16#ff,
 Octet3 = Bits4x6 band 16#ff,
- [Octet1, Octet2, Octet3 | mime_decode_list_to_string(Cs)];
+ [Octet1, Octet2, Octet3 | mime_decode_list_to_string(ModeOffset, Cs)];
 eq ->
- mime_decode_list_to_string_after_eq(Cs, B1, B2, B3);
- _ -> mime_decode_list_to_string(Cs, B1, B2, B3)
+ mime_decode_list_to_string_after_eq(ModeOffset, Cs, B1, B2, B3);
+ _ -> mime_decode_list_to_string(ModeOffset, Cs, B1, B2, B3)
 end.
 
-mime_decode_list_to_string_after_eq([0 | Cs], B1, B2, B3) ->
- mime_decode_list_to_string_after_eq(Cs, B1, B2, B3);
-mime_decode_list_to_string_after_eq([C | Cs], B1, B2, B3) ->
- case b64d(C) of
+mime_decode_list_to_string_after_eq(ModeOffset, [C | Cs], B1, B2, B3) ->
+ case b64d(C, ModeOffset) of
 B when is_integer(B) ->
 %% More valid data, skip the eq as invalid
 case B3 of
- eq -> mime_decode_list_to_string(Cs, B1, B2, B);
+ eq -> mime_decode_list_to_string(ModeOffset, Cs, B1, B2, B);
 _ ->
 Bits4x6 = (B1 bsl 18) bor (B2 bsl 12) bor (B3 bsl 6) bor B,
 Octet1 = Bits4x6 bsr 16,
 Octet2 = (Bits4x6 bsr 8) band 16#ff,
 Octet3 = Bits4x6 band 16#ff,
- [Octet1, Octet2, Octet3 | mime_decode_list_to_string(Cs)]
+ [Octet1, Octet2, Octet3 | mime_decode_list_to_string(ModeOffset, Cs)]
 end;
- _ -> mime_decode_list_to_string_after_eq(Cs, B1, B2, B3)
+ _ -> mime_decode_list_to_string_after_eq(ModeOffset, Cs, B1, B2, B3)
 end;
-mime_decode_list_to_string_after_eq([], B1, B2, eq) ->
+mime_decode_list_to_string_after_eq(_ModeOffset, [], B1, B2, eq) ->
 binary_to_list(<<B1:6,(B2 bsr 4):2>>);
-mime_decode_list_to_string_after_eq([], B1, B2, B3) ->
+mime_decode_list_to_string_after_eq(_ModeOffset, [], B1, B2, B3) ->
 binary_to_list(<<B1:6,B2:6,(B3 bsr 2):4>>).
 
-decode_list([C1 | Cs], A) ->
- case b64d(C1) of
- ws -> decode_list(Cs, A);
- B1 -> decode_list(Cs, A, B1)
+decode_list(ModeOffset, [C1 | Cs], A) ->
+ case b64d(C1, ModeOffset) of
+ ws -> decode_list(ModeOffset, Cs, A);
+ B1 -> decode_list(ModeOffset, Cs, A, B1)
 end;
-decode_list([], A) ->
+decode_list(_ModeOffset, [], A) ->
 A.
 
-decode_list([C2 | Cs], A, B1) ->
- case b64d(C2) of
- ws -> decode_list(Cs, A, B1);
- B2 -> decode_list(Cs, A, B1, B2)
+decode_list(ModeOffset, [C2 | Cs], A, B1) ->
+ case b64d(C2, ModeOffset) of
+ ws -> decode_list(ModeOffset, Cs, A, B1);
+ B2 -> decode_list(ModeOffset, Cs, A, B1, B2)
 end.
 
-decode_list([C3 | Cs], A, B1, B2) ->
- case b64d(C3) of
- ws -> decode_list(Cs, A, B1, B2);
- B3 -> decode_list(Cs, A, B1, B2, B3)
+decode_list(ModeOffset, [C3 | Cs], A, B1, B2) ->
+ case b64d(C3, ModeOffset) of
+ ws -> decode_list(ModeOffset, Cs, A, B1, B2);
+ B3 -> decode_list(ModeOffset, Cs, A, B1, B2, B3)
 end.
 
-decode_list([C4 | Cs], A, B1, B2, B3) ->
- case b64d(C4) of
- ws -> decode_list(Cs, A, B1, B2, B3);
- eq when B3 =:= eq -> only_ws(Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
- eq -> only_ws(Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
- B4 -> decode_list(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
+decode_list(ModeOffset, [C4 | Cs], A, B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
+ ws -> decode_list(ModeOffset, Cs, A, B1, B2, B3);
+ eq when B3 =:= eq -> only_ws(ModeOffset, Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
+ eq -> only_ws(ModeOffset, Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
+ B4 -> decode_list(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
 end.
 
-decode_binary(<<C1:8, C2:8, C3:8, C4:8, Cs/bits>>, A) ->
- case {b64d(C1), b64d(C2), b64d(C3), b64d(C4)} of
+decode_binary(ModeOffset, <<C1:8, C2:8, C3:8, C4:8, Cs/bits>>, A) ->
+ case {b64d(C1, ModeOffset), b64d(C2, ModeOffset), b64d(C3, ModeOffset), b64d(C4, ModeOffset)} of
 {B1, B2, B3, B4} when is_integer(B1), is_integer(B2),
 is_integer(B3), is_integer(B4) ->
- decode_binary(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
+ decode_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>);
 {B1, B2, B3, B4} ->
- dec_bin(Cs, B1, B2, B3, B4, A)
+ dec_bin(ModeOffset, Cs, B1, B2, B3, B4, A)
 end;
-decode_binary(<<>>, A) ->
+decode_binary(_ModeOffset, <<>>, A) ->
 A;
-decode_binary(<<C1:8, Cs/bits>>, A) ->
- case b64d(C1) of
- ws -> decode_binary(Cs, A);
- B1 -> decode_binary(Cs, A, B1)
+decode_binary(ModeOffset, <<C1:8, Cs/bits>>, A) ->
+ case b64d(C1, ModeOffset) of
+ ws -> decode_binary(ModeOffset, Cs, A);
+ B1 -> decode_binary(ModeOffset, Cs, A, B1)
 end.
 
-dec_bin(Cs, ws, B2, B3, B4, A) ->
- dec_bin(Cs, B2, B3, B4, A);
-dec_bin(Cs, B1, ws, B3, B4, A) ->
- dec_bin(Cs, B1, B3, B4, A);
-dec_bin(Cs, B1, B2, ws, B4, A) ->
- dec_bin(Cs, B1, B2, B4, A);
-dec_bin(Cs, B1, B2, B3, B4, A) ->
+dec_bin(ModeOffset, Cs, ws, B2, B3, B4, A) ->
+ dec_bin(ModeOffset, Cs, B2, B3, B4, A);
+dec_bin(ModeOffset, Cs, B1, ws, B3, B4, A) ->
+ dec_bin(ModeOffset, Cs, B1, B3, B4, A);
+dec_bin(ModeOffset, Cs, B1, B2, ws, B4, A) ->
+ dec_bin(ModeOffset, Cs, B1, B2, B4, A);
+dec_bin(ModeOffset, Cs, B1, B2, B3, B4, A) ->
 case B4 of
- ws -> decode_binary(Cs, A, B1, B2, B3);
- eq when B3 =:= eq -> only_ws_binary(Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
- eq -> only_ws_binary(Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
- B4 -> decode_binary(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
+ ws -> decode_binary(ModeOffset, Cs, A, B1, B2, B3);
+ eq when B3 =:= eq -> only_ws_binary(ModeOffset, Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
+ eq -> only_ws_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
+ B4 -> decode_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
 end.
 
-dec_bin(Cs, ws, B2, B3, A) ->
- dec_bin(Cs, B2, B3, A);
-dec_bin(Cs, B1, ws, B3, A) ->
- dec_bin(Cs, B1, B3, A);
-dec_bin(Cs, B1, B2, ws, A) ->
- dec_bin(Cs, B1, B2, A);
-dec_bin(Cs, B1, B2, B3, A) ->
- decode_binary(Cs, A, B1, B2, B3).
-
-dec_bin(Cs, ws, B2, A) ->
- dec_bin(Cs, B2, A);
-dec_bin(Cs, B1, ws, A) ->
- dec_bin(Cs, B1, A);
-dec_bin(Cs, B1, B2, A) ->
- decode_binary(Cs, A, B1, B2).
-
-dec_bin(Cs, ws, A) ->
- decode_binary(Cs, A);
-dec_bin(Cs, B1, A) ->
- decode_binary(Cs, A, B1).
-
-decode_binary(<<C2:8, Cs/bits>>, A, B1) ->
- case b64d(C2) of
- ws -> decode_binary(Cs, A, B1);
- B2 -> decode_binary(Cs, A, B1, B2)
+dec_bin(ModeOffset, Cs, ws, B2, B3, A) ->
+ dec_bin(ModeOffset, Cs, B2, B3, A);
+dec_bin(ModeOffset, Cs, B1, ws, B3, A) ->
+ dec_bin(ModeOffset, Cs, B1, B3, A);
+dec_bin(ModeOffset, Cs, B1, B2, ws, A) ->
+ dec_bin(ModeOffset, Cs, B1, B2, A);
+dec_bin(ModeOffset, Cs, B1, B2, B3, A) ->
+ decode_binary(ModeOffset, Cs, A, B1, B2, B3).
+
+dec_bin(ModeOffset, Cs, ws, B2, A) ->
+ dec_bin(ModeOffset, Cs, B2, A);
+dec_bin(ModeOffset, Cs, B1, ws, A) ->
+ dec_bin(ModeOffset, Cs, B1, A);
+dec_bin(ModeOffset, Cs, B1, B2, A) ->
+ decode_binary(ModeOffset, Cs, A, B1, B2).
+
+dec_bin(ModeOffset, Cs, ws, A) ->
+ decode_binary(ModeOffset, Cs, A);
+dec_bin(ModeOffset, Cs, B1, A) ->
+ decode_binary(ModeOffset, Cs, A, B1).
+
+decode_binary(ModeOffset, <<C2:8, Cs/bits>>, A, B1) ->
+ case b64d(C2, ModeOffset) of
+ ws -> decode_binary(ModeOffset, Cs, A, B1);
+ B2 -> decode_binary(ModeOffset, Cs, A, B1, B2)
 end.
 
-decode_binary(<<C3:8, Cs/bits>>, A, B1, B2) ->
- case b64d(C3) of
- ws -> decode_binary(Cs, A, B1, B2);
- B3 -> decode_binary(Cs, A, B1, B2, B3)
+decode_binary(ModeOffset, <<C3:8, Cs/bits>>, A, B1, B2) ->
+ case b64d(C3, ModeOffset) of
+ ws -> decode_binary(ModeOffset, Cs, A, B1, B2);
+ B3 -> decode_binary(ModeOffset, Cs, A, B1, B2, B3)
 end.
 
-decode_binary(<<C4:8, Cs/bits>>, A, B1, B2, B3) ->
- case b64d(C4) of
- ws -> decode_binary(Cs, A, B1, B2, B3);
- eq when B3 =:= eq -> only_ws_binary(Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
- eq -> only_ws_binary(Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
- B4 -> decode_binary(Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
+decode_binary(ModeOffset, <<C4:8, Cs/bits>>, A, B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
+ ws -> decode_binary(ModeOffset, Cs, A, B1, B2, B3);
+ eq when B3 =:= eq -> only_ws_binary(ModeOffset, Cs, <<A/bits,B1:6,(B2 bsr 4):2>>);
+ eq -> only_ws_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,(B3 bsr 2):4>>);
+ B4 -> decode_binary(ModeOffset, Cs, <<A/bits,B1:6,B2:6,B3:6,B4:6>>)
 end.
 
-only_ws_binary(<<>>, A) ->
+only_ws_binary(_ModeOffset, <<>>, A) ->
 A;
-only_ws_binary(<<C:8, Cs/bits>>, A) ->
- case b64d(C) of
- ws -> only_ws_binary(Cs, A)
+only_ws_binary(ModeOffset, <<C:8, Cs/bits>>, A) ->
+ case b64d(C, ModeOffset) of
+ ws -> only_ws_binary(ModeOffset, Cs, A)
 end.
 
-decode_list_to_string([C1 | Cs]) ->
- case b64d(C1) of
- ws -> decode_list_to_string(Cs);
- B1 -> decode_list_to_string(Cs, B1)
+decode_list_to_string(ModeOffset, [C1 | Cs]) ->
+ case b64d(C1, ModeOffset) of
+ ws -> decode_list_to_string(ModeOffset, Cs);
+ B1 -> decode_list_to_string(ModeOffset, Cs, B1)
 end;
-decode_list_to_string([]) ->
+decode_list_to_string(_ModeOffset, []) ->
 [].
 
-decode_list_to_string([C2 | Cs], B1) ->
- case b64d(C2) of
- ws -> decode_list_to_string(Cs, B1);
- B2 -> decode_list_to_string(Cs, B1, B2)
+decode_list_to_string(ModeOffset, [C2 | Cs], B1) ->
+ case b64d(C2, ModeOffset) of
+ ws -> decode_list_to_string(ModeOffset, Cs, B1);
+ B2 -> decode_list_to_string(ModeOffset, Cs, B1, B2)
 end.
 
-decode_list_to_string([C3 | Cs], B1, B2) ->
- case b64d(C3) of
- ws -> decode_list_to_string(Cs, B1, B2);
- B3 -> decode_list_to_string(Cs, B1, B2, B3)
+decode_list_to_string(ModeOffset, [C3 | Cs], B1, B2) ->
+ case b64d(C3, ModeOffset) of
+ ws -> decode_list_to_string(ModeOffset, Cs, B1, B2);
+ B3 -> decode_list_to_string(ModeOffset, Cs, B1, B2, B3)
 end.
 
-decode_list_to_string([C4 | Cs], B1, B2, B3) ->
- case b64d(C4) of
+decode_list_to_string(ModeOffset, [C4 | Cs], B1, B2, B3) ->
+ case b64d(C4, ModeOffset) of
 ws ->
- decode_list_to_string(Cs, B1, B2, B3);
+ decode_list_to_string(ModeOffset, Cs, B1, B2, B3);
 eq when B3 =:= eq ->
- only_ws(Cs, binary_to_list(<<B1:6,(B2 bsr 4):2>>));
+ only_ws(ModeOffset, Cs, binary_to_list(<<B1:6,(B2 bsr 4):2>>));
 eq ->
- only_ws(Cs, binary_to_list(<<B1:6,B2:6,(B3 bsr 2):4>>));
+ only_ws(ModeOffset, Cs, binary_to_list(<<B1:6,B2:6,(B3 bsr 2):4>>));
 B4 ->
 Bits4x6 = (B1 bsl 18) bor (B2 bsl 12) bor (B3 bsl 6) bor B4,
 Octet1 = Bits4x6 bsr 16,
 Octet2 = (Bits4x6 bsr 8) band 16#ff,
 Octet3 = Bits4x6 band 16#ff,
- [Octet1, Octet2, Octet3 | decode_list_to_string(Cs)]
+ [Octet1, Octet2, Octet3 | decode_list_to_string(ModeOffset, Cs)]
 end.
 
-only_ws([], A) ->
+only_ws(_ModeOffset, [], A) ->
 A;
-only_ws([C | Cs], A) ->
- case b64d(C) of
- ws -> only_ws(Cs, A)
+only_ws(ModeOffset, [C | Cs], A) ->
+ case b64d(C, ModeOffset) of
+ ws -> only_ws(ModeOffset, Cs, A)
 end.
 
 %%%========================================================================
@@ -493,14 +521,19 @@ only_ws([C | Cs], A) ->
 %%%========================================================================
 
 %% accessors 
--compile({inline, [{b64d, 1}]}).
-%% One-based decode map.
-b64d(X) ->
- element(X,
- {bad,bad,bad,bad,bad,bad,bad,bad,ws,ws,bad,bad,ws,bad,bad, %1-15
+
+get_decoding_offset(standard) -> 1;
+get_decoding_offset(urlsafe) -> 257.
+
+-compile({inline, [{b64d, 2}]}).
+b64d(X, Off) ->
+ element(X + Off,
+ {
+	 %% standard base64 alphabet (RFC 4648 Section 4)
+	 bad,bad,bad,bad,bad,bad,bad,bad,bad,ws,ws,bad,bad,ws,bad,bad, %0-15
 bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad, %16-31
 ws,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,62,bad,bad,bad,63, %32-47
- 52,53,54,55,56,57,58,59,60,61,bad,bad,bad,eq,bad,bad, %48-63
+ 52,53,54,55,56,57,58,59,60,61,bad,bad,bad,eq,bad,bad, %48-61
 bad,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,
 15,16,17,18,19,20,21,22,23,24,25,bad,bad,bad,bad,bad,
 bad,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
@@ -512,13 +545,44 @@ b64d(X) ->
 bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
 bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
 bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+
+	 %% alternative base64url alphabet (RFC 4648 Section 5)
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,ws,ws,bad,bad,ws,bad,bad, %0-15
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad, %16-31
+ ws,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,62,bad,bad, %32-47
+ 52,53,54,55,56,57,58,59,60,61,bad,bad,bad,eq,bad,bad, %48-61
+ bad,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,
+ 15,16,17,18,19,20,21,22,23,24,25,bad,bad,bad,bad,63,
+ bad,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,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
+ bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
 bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad}).
 
--compile({inline, [{b64e, 1}]}).
-b64e(X) ->
- element(X+1,
-	 {$A, $B, $C, $D, $E, $F, $G, $H, $I, $J, $K, $L, $M, $N,
+get_encoding_offset(standard) -> 1;
+get_encoding_offset(urlsafe) -> 65.
+
+-compile({inline, [{b64e, 2}]}).
+b64e(X, Off) ->
+ element(X + Off,
+	 {
+	 %% standard base64 alphabet (RFC 4648 Section 4)
+	 $A, $B, $C, $D, $E, $F, $G, $H, $I, $J, $K, $L, $M, $N,
+	 $O, $P, $Q, $R, $S, $T, $U, $V, $W, $X, $Y, $Z,
+	 $a, $b, $c, $d, $e, $f, $g, $h, $i, $j, $k, $l, $m, $n,
+	 $o, $p, $q, $r, $s, $t, $u, $v, $w, $x, $y, $z,
+	 $0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $+, $/,
+
+	 %% alternative base64url alphabet (RFC 4648 Section 5)
+	 $A, $B, $C, $D, $E, $F, $G, $H, $I, $J, $K, $L, $M, $N,
 	 $O, $P, $Q, $R, $S, $T, $U, $V, $W, $X, $Y, $Z,
 	 $a, $b, $c, $d, $e, $f, $g, $h, $i, $j, $k, $l, $m, $n,
 	 $o, $p, $q, $r, $s, $t, $u, $v, $w, $x, $y, $z,
-	 $0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $+, $/}).
+	 $0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $-, $_}).
+
diff --git a/lib/stdlib/test/base64_SUITE.erl b/lib/stdlib/test/base64_SUITE.erl
index 1fc4c3fc0e..d1625108bd 100644
--- a/lib/stdlib/test/base64_SUITE.erl
+++ b/lib/stdlib/test/base64_SUITE.erl
@@ -26,9 +26,11 @@
 -export([all/0, suite/0, groups/0, group/1]).
 
 %% Test cases must be exported.
--export([base64_encode/1, base64_decode/1, base64_otp_5635/1,
-	 base64_otp_6279/1, big/1, illegal/1, mime_decode/1,
-	 mime_decode_to_string/1,
+-export([base64_encode/1, base64_encode_modes/1,
+	 base64_decode/1, base64_decode_modes/1,
+	 base64_otp_5635/1, base64_otp_6279/1, big/1, illegal/1,
+	 mime_decode/1, mime_decode_modes/1,
+	 mime_decode_to_string/1, mime_decode_to_string_modes/1,
 	 roundtrip_1/1, roundtrip_2/1, roundtrip_3/1, roundtrip_4/1]).
 
 %%-------------------------------------------------------------------------
@@ -40,8 +42,11 @@ suite() ->
 {timetrap,{minutes,4}}].
 
 all() ->
- [base64_encode, base64_decode, base64_otp_5635,
- base64_otp_6279, big, illegal, mime_decode, mime_decode_to_string,
+ [base64_encode, base64_encode_modes,
+ base64_decode, base64_decode_modes,
+ base64_otp_5635, base64_otp_6279, big, illegal,
+ mime_decode, mime_decode_modes,
+ mime_decode_to_string, mime_decode_to_string_modes,
 {group, roundtrip}].
 
 groups() ->
@@ -67,6 +72,20 @@ base64_encode(Config) when is_list(Config) ->
 "MDEyMzQ1Njc4OSFAIzBeJiooKTs6PD4sLiBbXXt9" =
 	base64:encode_to_string(<<"0123456789!@#0^&*();:<>,. []{}">>),
 ok.
+
+%%-------------------------------------------------------------------------
+%% Test base64:encode/2.
+base64_encode_modes(Config) when is_list(Config) ->
+ Data = <<23, 234, 63, 163, 239, 129, 253, 175, 171>>,
+
+ <<"F+o/o++B/a+r">> = base64:encode(Data, standard),
+ <<"F-o_o--B_a-r">> = base64:encode(Data, urlsafe),
+
+ "F+o/o++B/a+r" = base64:encode_to_string(Data, standard),
+ "F-o_o--B_a-r" = base64:encode_to_string(Data, urlsafe),
+
+ ok.
+
 %%-------------------------------------------------------------------------
 %% Test base64:decode/1.
 base64_decode(Config) when is_list(Config) ->
@@ -91,6 +110,24 @@ base64_decode(Config) when is_list(Config) ->
 	base64:decode_to_string(
 	 <<"MDEy MzQ1Njc4 \tOSFAIzBeJ \niooKTs6 PD4sLi \r\nBbXXt9">>),
 ok.
+
+%%-------------------------------------------------------------------------
+%% Test base64:decode/2.
+base64_decode_modes(Config) when is_list(Config) ->
+ DataBin = <<23, 234, 63, 163, 239, 129, 253, 175, 171>>,
+ DataStr = [23, 234, 63, 163, 239, 129, 253, 175, 171],
+
+ DataBin = base64:decode("F+o/o++B/a+r", standard),
+ DataBin = base64:decode("F-o_o--B_a-r", urlsafe),
+ {'EXIT', _} = catch base64:decode("F-o_o--B_a-r", standard),
+ {'EXIT', _} = catch base64:decode("F+o/o++B/a+r", urlsafe),
+
+ DataStr = base64:decode_to_string("F+o/o++B/a+r", standard),
+ DataStr = base64:decode_to_string("F-o_o--B_a-r", urlsafe),
+ {'EXIT', _} = catch base64:decode_to_string("F-o_o--B_a-r", standard),
+ {'EXIT', _} = catch base64:decode_to_string("F+o/o++B/a+r", urlsafe),
+
+ ok.
 %%-------------------------------------------------------------------------
 %% OTP-5635: Some data doesn't pass through base64:decode/1 correctly.
 base64_otp_5635(Config) when is_list(Config) ->
@@ -171,6 +208,31 @@ mime_decode(Config) when is_list(Config) ->
 <<"o">> = MimeDecode(<<"bw=\000=">>),
 ok.
 
+%% Test base64:mime_decode/2.
+mime_decode_modes(Config) when is_list(Config) ->
+ MimeDecode = fun (In, Mode) ->
+ Out = base64:mime_decode(In, Mode),
+ Out = base64:mime_decode(binary_to_list(In), Mode)
+ end,
+
+ %% The following all decode to the same data.
+ Data = <<23, 234, 63, 163, 239, 129, 253, 175, 171>>,
+ Data = MimeDecode(<<"F+o/o++B/a+r">>, standard),
+ Data = MimeDecode(<<"F-o_o--B_a-r">>, urlsafe),
+
+ %% The following decodes to different data depending on mode.
+ Base64 = <<"AB+C+D/E/FG-H-I_J_KL">>,
+ %% In standard mode, "-" and "_" are invalid and thus ignored.
+ %% The base64 string to be decoded is equivalent to "AB+C+D/E/FGHIJKL".
+ <<0, 31, 130, 248, 63, 196, 252, 81, 135, 32, 146, 139>> =
+ MimeDecode(Base64, standard),
+ %% In urlsafe mode, "+" and "/" are invalid and thus ignored.
+ %% The base64 string to be decoded is equivalent to "ABCDEFG-H-I_J_KL".
+ <<0, 16, 131, 16, 81, 190, 31, 226, 63, 39, 242, 139>> =
+ MimeDecode(Base64, urlsafe),
+
+ ok.
+
 %%-------------------------------------------------------------------------
 
 %% Repeat of mime_decode() tests
@@ -221,6 +283,32 @@ mime_decode_to_string(Config) when is_list(Config) ->
 "o" = MimeDecodeToString(<<"bw=\000=">>),
 ok.
 
+
+%% Test base64:mime_decode_to_string/2.
+mime_decode_to_string_modes(Config) when is_list(Config) ->
+ MimeDecode = fun (In, Mode) ->
+ Out = base64:mime_decode_to_string(In, Mode),
+ Out = base64:mime_decode_to_string(binary_to_list(In), Mode)
+ end,
+
+ %% The following all decode to the same data.
+ Data = [23, 234, 63, 163, 239, 129, 253, 175, 171],
+ Data = MimeDecode(<<"F+o/o++B/a+r">>, standard),
+ Data = MimeDecode(<<"F-o_o--B_a-r">>, urlsafe),
+
+ %% The following decodes to different data depending on mode.
+ Base64 = <<"AB+C+D/E/FG-H-I_J_KL">>,
+ %% In standard mode, "-" and "_" are invalid and thus ignored.
+ %% The base64 string to be decoded is equivalent to "AB+C+D/E/FGHIJKL".
+ [0, 31, 130, 248, 63, 196, 252, 81, 135, 32, 146, 139] =
+ MimeDecode(Base64, standard),
+ %% In urlsafe mode, "+" and "/" are invalid and thus ignored.
+ %% The base64 string to be decoded is equivalent to "ABCDEFG-H-I_J_KL".
+ [0, 16, 131, 16, 81, 190, 31, 226, 63, 39, 242, 139] =
+ MimeDecode(Base64, urlsafe),
+
+ ok.
+
 %%-------------------------------------------------------------------------
 
 roundtrip_1(Config) when is_list(Config) ->
diff --git a/lib/stdlib/test/base64_property_test_SUITE.erl b/lib/stdlib/test/base64_property_test_SUITE.erl
index 3802b68ce3..0b8d1f69e3 100644
--- a/lib/stdlib/test/base64_property_test_SUITE.erl
+++ b/lib/stdlib/test/base64_property_test_SUITE.erl
@@ -24,18 +24,18 @@
 
 all() ->
 [
- encode_case,
- encode_to_string_case,
- decode_case,
- decode_malformed_case,
- decode_noisy_case,
- decode_to_string_case,
- decode_to_string_malformed_case,
- decode_to_string_noisy_case,
- mime_decode_case,
- mime_decode_malformed_case,
- mime_decode_to_string_case,
- mime_decode_to_string_malformed_case
+ encode_1_case, encode_2_case,
+ encode_to_string_1_case, encode_to_string_2_case,
+ decode_1_case, decode_2_case,
+ decode_1_malformed_case, decode_2_malformed_case,
+ decode_1_noisy_case, decode_2_noisy_case,
+ decode_to_string_1_case, decode_to_string_2_case,
+ decode_to_string_1_malformed_case, decode_to_string_2_malformed_case,
+ decode_to_string_1_noisy_case, decode_to_string_2_noisy_case,
+ mime_decode_1_case, mime_decode_2_case,
+ mime_decode_1_malformed_case, mime_decode_2_malformed_case,
+ mime_decode_to_string_1_case, mime_decode_to_string_2_case,
+ mime_decode_to_string_1_malformed_case, mime_decode_to_string_2_malformed_case
 ].
 
 init_per_suite(Config) ->
@@ -44,41 +44,77 @@ init_per_suite(Config) ->
 end_per_suite(Config) ->
 Config.
 
-encode_case(Config) ->
- do_proptest(prop_encode, Config).
+encode_1_case(Config) ->
+ do_proptest(prop_encode_1, Config).
 
-encode_to_string_case(Config) ->
- do_proptest(prop_encode_to_string, Config).
+encode_2_case(Config) ->
+ do_proptest(prop_encode_2, Config).
 
-decode_case(Config) ->
- do_proptest(prop_decode, Config).
+encode_to_string_1_case(Config) ->
+ do_proptest(prop_encode_to_string_1, Config).
 
-decode_malformed_case(Config) ->
- do_proptest(prop_decode_malformed, Config).
+encode_to_string_2_case(Config) ->
+ do_proptest(prop_encode_to_string_2, Config).
 
-decode_noisy_case(Config) ->
- do_proptest(prop_decode_noisy, Config).
+decode_1_case(Config) ->
+ do_proptest(prop_decode_1, Config).
 
-decode_to_string_case(Config) ->
- do_proptest(prop_decode_to_string, Config).
+decode_2_case(Config) ->
+ do_proptest(prop_decode_2, Config).
 
-decode_to_string_malformed_case(Config) ->
- do_proptest(prop_decode_to_string_malformed, Config).
+decode_1_malformed_case(Config) ->
+ do_proptest(prop_decode_1_malformed, Config).
 
-decode_to_string_noisy_case(Config) ->
- do_proptest(prop_decode_to_string_noisy, Config).
+decode_2_malformed_case(Config) ->
+ do_proptest(prop_decode_2_malformed, Config).
 
-mime_decode_case(Config) ->
- do_proptest(prop_mime_decode, Config).
+decode_1_noisy_case(Config) ->
+ do_proptest(prop_decode_1_noisy, Config).
 
-mime_decode_malformed_case(Config) ->
- do_proptest(prop_mime_decode_malformed, Config).
+decode_2_noisy_case(Config) ->
+ do_proptest(prop_decode_2_noisy, Config).
 
-mime_decode_to_string_case(Config) ->
- do_proptest(prop_mime_decode_to_string, Config).
+decode_to_string_1_case(Config) ->
+ do_proptest(prop_decode_to_string_1, Config).
 
-mime_decode_to_string_malformed_case(Config) ->
- do_proptest(prop_mime_decode_to_string_malformed, Config).
+decode_to_string_2_case(Config) ->
+ do_proptest(prop_decode_to_string_2, Config).
+
+decode_to_string_1_malformed_case(Config) ->
+ do_proptest(prop_decode_to_string_1_malformed, Config).
+
+decode_to_string_2_malformed_case(Config) ->
+ do_proptest(prop_decode_to_string_2_malformed, Config).
+
+decode_to_string_1_noisy_case(Config) ->
+ do_proptest(prop_decode_to_string_1_noisy, Config).
+
+decode_to_string_2_noisy_case(Config) ->
+ do_proptest(prop_decode_to_string_2_noisy, Config).
+
+mime_decode_1_case(Config) ->
+ do_proptest(prop_mime_decode_1, Config).
+
+mime_decode_2_case(Config) ->
+ do_proptest(prop_mime_decode_2, Config).
+
+mime_decode_1_malformed_case(Config) ->
+ do_proptest(prop_mime_decode_1_malformed, Config).
+
+mime_decode_2_malformed_case(Config) ->
+ do_proptest(prop_mime_decode_2_malformed, Config).
+
+mime_decode_to_string_1_case(Config) ->
+ do_proptest(prop_mime_decode_to_string_1, Config).
+
+mime_decode_to_string_2_case(Config) ->
+ do_proptest(prop_mime_decode_to_string_2, Config).
+
+mime_decode_to_string_1_malformed_case(Config) ->
+ do_proptest(prop_mime_decode_to_string_1_malformed, Config).
+
+mime_decode_to_string_2_malformed_case(Config) ->
+ do_proptest(prop_mime_decode_to_string_2_malformed, Config).
 
 do_proptest(Prop, Config) ->
 ct_property_test:quickcheck(
diff --git a/lib/stdlib/test/property_test/base64_prop.erl b/lib/stdlib/test/property_test/base64_prop.erl
index 6ab7e4c68a..44b1811936 100644
--- a/lib/stdlib/test/property_test/base64_prop.erl
+++ b/lib/stdlib/test/property_test/base64_prop.erl
@@ -54,96 +54,200 @@
 %%% Properties %%%
 %%%%%%%%%%%%%%%%%%
 
-prop_encode() ->
+prop_encode_1() ->
 ?FORALL(
 Str,
 oneof([list(byte()), binary()]),
 begin
 Enc = base64:encode(Str),
 Dec = base64:decode(Enc),
- is_b64_binary(Enc) andalso str_equals(Str, Dec)
+ is_b64_binary(standard, Enc) andalso str_equals(Str, Dec)
 end
 ).
 
-prop_encode_to_string() ->
+prop_encode_2() ->
+ ?FORALL(
+ {Str, Mode},
+ {oneof([list(byte()), binary()]), mode()},
+ begin
+ Enc = base64:encode(Str, Mode),
+ Dec = base64:decode(Enc, Mode),
+ is_b64_binary(Mode, Enc) andalso str_equals(Str, Dec)
+ end
+ ).
+
+prop_encode_to_string_1() ->
 ?FORALL(
 Str,
 oneof([list(byte()), binary()]),
 begin
 Enc = base64:encode_to_string(Str),
 Dec = base64:decode_to_string(Enc),
- is_b64_string(Enc) andalso str_equals(Str, Dec)
+ is_b64_string(standard, Enc) andalso str_equals(Str, Dec)
+ end
+ ).
+
+prop_encode_to_string_2() ->
+ ?FORALL(
+ {Str, Mode},
+ {oneof([list(byte()), binary()]), mode()},
+ begin
+ Enc = base64:encode_to_string(Str, Mode),
+ Dec = base64:decode_to_string(Enc, Mode),
+ is_b64_string(Mode, Enc) andalso str_equals(Str, Dec)
 end
 ).
 
-prop_decode() ->
+prop_decode_1() ->
 ?FORALL(
 {NormalizedB64, WspedB64},
- wsped_b64(),
+ wsped_b64(standard),
 begin
 Dec = base64:decode(WspedB64),
 Enc = base64:encode(Dec),
- is_binary(Dec) andalso b64_equals(NormalizedB64, Enc)
+ is_binary(Dec) andalso b64_equals(standard, NormalizedB64, Enc)
+ end
+ ).
+
+prop_decode_2() ->
+ ?FORALL(
+ {{NormalizedB64, WspedB64}, Mode},
+ ?LET(
+ Mode,
+ mode(),
+ {wsped_b64(Mode), Mode}
+ ),
+ begin
+ Dec = base64:decode(WspedB64, Mode),
+ Enc = base64:encode(Dec, Mode),
+ is_binary(Dec) andalso b64_equals(Mode, NormalizedB64, Enc)
 end
 ).
 
-prop_decode_malformed() ->
- common_decode_malformed(wsped_b64(), fun base64:decode/1).
+prop_decode_1_malformed() ->
+ common_decode_malformed(fun wsped_b64/1, standard, fun(Data, _) -> base64:decode(Data) end).
+
+prop_decode_2_malformed() ->
+ common_decode_malformed(fun wsped_b64/1, mode(), fun base64:decode/2).
 
-prop_decode_noisy() ->
- common_decode_noisy(fun base64:decode/1).
+prop_decode_1_noisy() ->
+ common_decode_noisy(standard, fun(Data, _) -> base64:decode(Data) end).
 
-prop_decode_to_string() ->
+prop_decode_2_noisy() ->
+ common_decode_noisy(mode(), fun base64:decode/2).
+
+prop_decode_to_string_1() ->
 ?FORALL(
 {NormalizedB64, WspedB64},
- wsped_b64(),
+ wsped_b64(standard),
 begin
 Dec = base64:decode_to_string(WspedB64),
 Enc = base64:encode(Dec),
- is_bytelist(Dec) andalso b64_equals(NormalizedB64, Enc)
+ is_bytelist(Dec) andalso b64_equals(standard, NormalizedB64, Enc)
+ end
+ ).
+
+prop_decode_to_string_2() ->
+ ?FORALL(
+ {{NormalizedB64, WspedB64}, Mode},
+ ?LET(
+ Mode,
+ mode(),
+ {wsped_b64(Mode), Mode}
+ ),
+ begin
+ Dec = base64:decode_to_string(WspedB64, Mode),
+ Enc = base64:encode(Dec, Mode),
+ is_bytelist(Dec) andalso b64_equals(Mode, NormalizedB64, Enc)
 end
 ).
 
-prop_decode_to_string_malformed() ->
- common_decode_malformed(wsped_b64(), fun base64:decode_to_string/1).
+prop_decode_to_string_1_malformed() ->
+ common_decode_malformed(fun wsped_b64/1, standard, fun(Data, _) -> base64:decode_to_string(Data) end).
+
+prop_decode_to_string_2_malformed() ->
+ common_decode_malformed(fun wsped_b64/1, mode(), fun base64:decode_to_string/2).
+
+prop_decode_to_string_1_noisy() ->
+ common_decode_noisy(standard, fun(Data, _) -> base64:decode_to_string(Data) end).
 
-prop_decode_to_string_noisy() ->
- common_decode_noisy(fun base64:decode_to_string/1).
+prop_decode_to_string_2_noisy() ->
+ common_decode_noisy(mode(), fun base64:decode_to_string/2).
 
-prop_mime_decode() ->
+prop_mime_decode_1() ->
 ?FORALL(
 {NormalizedB64, NoisyB64},
- noisy_b64(),
+ noisy_b64(standard),
 begin
 Dec = base64:mime_decode(NoisyB64),
 Enc = base64:encode(Dec),
- is_binary(Dec) andalso b64_equals(NormalizedB64, Enc)
+ is_binary(Dec) andalso b64_equals(standard, NormalizedB64, Enc)
 end
 ).
 
-prop_mime_decode_malformed() ->
- common_decode_malformed(noisy_b64(), fun base64:mime_decode/1).
+prop_mime_decode_2() ->
+ ?FORALL(
+ {{NormalizedB64, NoisyB64}, Mode},
+ ?LET(
+ Mode,
+ mode(),
+ {wsped_b64(Mode), Mode}
+ ),
+ begin
+ Dec = base64:mime_decode(NoisyB64, Mode),
+ Enc = base64:encode(Dec, Mode),
+ is_binary(Dec) andalso b64_equals(Mode, NormalizedB64, Enc)
+ end
+ ).
+
+prop_mime_decode_1_malformed() ->
+ common_decode_malformed(fun noisy_b64/1, standard, fun(Data, _) -> base64:mime_decode(Data) end).
 
-prop_mime_decode_to_string() ->
+prop_mime_decode_2_malformed() ->
+ common_decode_malformed(fun noisy_b64/1, mode(), fun base64:mime_decode/2).
+
+prop_mime_decode_to_string_1() ->
 ?FORALL(
 {NormalizedB64, NoisyB64},
- noisy_b64(),
+ noisy_b64(standard),
 begin
 Dec = base64:mime_decode_to_string(NoisyB64),
 Enc = base64:encode(Dec),
- is_bytelist(Dec) andalso b64_equals(NormalizedB64, Enc)
+ is_bytelist(Dec) andalso b64_equals(standard, NormalizedB64, Enc)
 end
 ).
 
-prop_mime_decode_to_string_malformed() ->
- common_decode_malformed(noisy_b64(), fun base64:mime_decode_to_string/1).
+prop_mime_decode_to_string_2() ->
+ ?FORALL(
+ {{NormalizedB64, NoisyB64}, Mode},
+ ?LET(
+ Mode,
+ mode(),
+ {wsped_b64(Mode), Mode}
+ ),
+ begin
+ Dec = base64:mime_decode_to_string(NoisyB64, Mode),
+ Enc = base64:encode(Dec, Mode),
+ is_bytelist(Dec) andalso b64_equals(Mode, NormalizedB64, Enc)
+ end
+ ).
 
-common_decode_noisy(Fn) ->
+prop_mime_decode_to_string_1_malformed() ->
+ common_decode_malformed(fun noisy_b64/1, standard, fun(Data, _) -> base64:mime_decode_to_string(Data) end).
+
+prop_mime_decode_to_string_2_malformed() ->
+ common_decode_malformed(fun noisy_b64/1, mode(), fun base64:mime_decode_to_string/2).
+
+common_decode_noisy(ModeGen, Fn) ->
 ?FORALL(
- {_, NoisyB64},
- ?SUCHTHAT({NormalizedB64, NoisyB64}, noisy_b64(), NormalizedB64 =/= NoisyB64),
+ {{_, NoisyB64}, Mode},
+ ?LET(
+ Mode,
+ ModeGen,
+ {?SUCHTHAT({NormalizedB64, NoisyB64}, noisy_b64(Mode), NormalizedB64 =/= NoisyB64), Mode}
+ ),
 try
- Fn(NoisyB64)
+ Fn(NoisyB64, Mode)
 of
 _ ->
 false
@@ -153,25 +257,30 @@ common_decode_noisy(Fn) ->
 end
 ).
 
-common_decode_malformed(Gen, Fn) ->
+common_decode_malformed(DataGen, ModeGen, Fn) ->
 ?FORALL(
- MalformedB64,
+ {MalformedB64, Mode},
 ?LET(
- {{NormalizedB64, NoisyB64}, Malformings},
- {
- Gen,
- oneof(
- [
- [b64_char()],
- [b64_char(), b64_char()],
- [b64_char(), b64_char(), b64_char()]
- ]
- )
- },
- {NormalizedB64, insert_noise(NoisyB64, Malformings)}
+ Mode,
+ ModeGen,
+ ?LET(
+ {{NormalizedB64, NoisyB64}, Malformings, InsertFn},
+ {
+ DataGen(Mode),
+ oneof(
+ [
+ [b64_char(Mode)],
+ [b64_char(Mode), b64_char(Mode)],
+ [b64_char(Mode), b64_char(Mode), b64_char(Mode)]
+ ]
+ ),
+ function1(boolean())
+ },
+ {{NormalizedB64, insert_noise(NoisyB64, Malformings, InsertFn)}, Mode}
+ )
 ),
 try
- Fn(MalformedB64)
+ Fn(MalformedB64, Mode)
 of
 _ ->
 false
@@ -185,16 +294,20 @@ common_decode_malformed(Gen, Fn) ->
 %%% Generators %%%
 %%%%%%%%%%%%%%%%%%
 
+%% Generate base64 encoding mode.
+mode() ->
+ oneof([standard, urlsafe]).
+
 %% Generate a single character from the base64 alphabet.
-b64_char() ->
- oneof(b64_chars()).
+b64_char(Mode) ->
+ oneof(b64_chars(Mode)).
 
 %% Generate a string of characters from the base64 alphabet,
 %% including padding if needed.
-b64_string() ->
+b64_string(Mode) ->
 ?LET(
 {L, Filler},
- {list(b64_char()), b64_char()},
+ {list(b64_char(Mode)), b64_char(Mode)},
 case length(L) rem 4 of
 0 -> L;
 1 -> L ++ [Filler, $=, $=];
@@ -205,43 +318,43 @@ b64_string() ->
 
 %% Generate a binary of characters from the base64 alphabet,
 %% including padding if needed.
-b64_binary() ->
+b64_binary(Mode) ->
 ?LET(
 L,
- b64_string(),
+ b64_string(Mode),
 list_to_binary(L)
 ).
 
 %% Generate a string or binary of characters from the
 %% base64 alphabet, including padding if needed.
-b64() ->
- oneof([b64_string(), b64_binary()]).
+b64(Mode) ->
+ oneof([b64_string(Mode), b64_binary(Mode)]).
 
 %% Generate a string or binary of characters from the
 %% base64 alphabet, including padding if needed, with
 %% whitespaces inserted at random indexes.
-wsped_b64() ->
+wsped_b64(Mode) ->
 ?LET(
- {B64, Wsps},
- {b64(), list(oneof([$\t, $\r, $\n, $\s]))},
- {B64, insert_noise(B64, Wsps)}
+ {B64, Wsps, InsertFn},
+ {b64(Mode), list(oneof([$\t, $\r, $\n, $\s])), function1(boolean())},
+ {B64, insert_noise(B64, Wsps, InsertFn)}
 ).
 
 %% Generate a single character outside of the base64 alphabet.
 %% As whitespaces are allowed but ignored in base64, this generator
 %% will produce no whitespaces, either.
-non_b64_char() ->
- oneof(lists:seq(16#00, 16#FF) -- b64_allowed_chars()).
+non_b64_char(Mode) ->
+ oneof(lists:seq(16#00, 16#FF) -- b64_allowed_chars(Mode)).
 
 %% Generate a string or binary of characters from the
 %% base64 alphabet, including padding if needed, with
 %% whitespaces and non-base64 ("invalid") characters
 %% inserted at random indexes.
-noisy_b64() ->
+noisy_b64(Mode) ->
 ?LET(
- {{B64, WspedB64}, Noise},
- {wsped_b64(), non_empty(list(non_b64_char()))},
- {B64, insert_noise(WspedB64, Noise)}
+ {{B64, WspedB64}, Noise, InsertFn},
+ {wsped_b64(Mode), non_empty(list(non_b64_char(Mode))), function1(boolean())},
+ {B64, insert_noise(WspedB64, Noise, InsertFn)}
 ).
 
 %%%%%%%%%%%%%%%
@@ -252,81 +365,92 @@ noisy_b64() ->
 %% "=" is not included, as it is special in that it
 %% may only appear at the end of a base64 encoded string
 %% for padding.
-b64_chars() ->
+b64_chars_common() ->
 lists:seq($0, $9) ++
 lists:seq($a, $z) ++
- lists:seq($A, $Z) ++
- [$+, $/].
+ lists:seq($A, $Z).
+
+b64_chars(standard) ->
+ b64_chars_common() ++ [$+, $/];
+b64_chars(urlsafe) ->
+ b64_chars_common() ++ [$-, $_].
 
 %% In addition to the above, the whitespace characters
 %% HTAB, CR, LF and SP are allowed to appear in a base64
 %% encoded string and should be ignored.
-b64_allowed_chars() ->
- [$\t, $\r, $\n, $\s | b64_chars()].
+b64_allowed_chars(Mode) ->
+ [$\t, $\r, $\n, $\s | b64_chars(Mode)].
 
 %% Insert the given list of noise characters at random
 %% places into the given base64 string.
-insert_noise(B64, []) ->
+insert_noise(B64, Noise, InsertFn) ->
+ insert_noise(B64, Noise, InsertFn, 0).
+
+insert_noise(B64, [], _, _) ->
 B64;
-insert_noise([], Noise) ->
+insert_noise([], Noise, _, _) ->
 Noise;
-insert_noise(<<>>, Noise) ->
+insert_noise(<<>>, Noise, _, _) ->
 list_to_binary(Noise);
-insert_noise([B|Bs] = B64, [N|Ns] = Noise) ->
- case rand:uniform(2) of
- 1 ->
- [B|insert_noise(Bs, Noise)];
- 2 ->
- [N|insert_noise(B64, Ns)]
+insert_noise([B|Bs] = B64, [N|Ns] = Noise, InsertFn, Idx) ->
+ case InsertFn(Idx) of
+ true ->
+ [B|insert_noise(Bs, Noise, InsertFn, Idx + 1)];
+ false ->
+ [N|insert_noise(B64, Ns, InsertFn, Idx + 1)]
 end;
-insert_noise(<<B, Bs/binary>> = B64, [N|Ns] = Noise) ->
- case rand:uniform(2) of
- 1 ->
- <<B, (insert_noise(Bs, Noise))/binary>>;
- 2 ->
- <<N, (insert_noise(B64, Ns))/binary>>
+insert_noise(<<B, Bs/binary>> = B64, [N|Ns] = Noise, InsertFn, Idx) ->
+ case InsertFn(Idx) of
+ true ->
+ <<B, (insert_noise(Bs, Noise, InsertFn, Idx + 1))/binary>>;
+ false ->
+ <<N, (insert_noise(B64, Ns, InsertFn, Idx + 1))/binary>>
 end.
 
 %% Check if the given character is in the base64 alphabet.
 %% This does not include the padding character "=".
-is_b64_char($+) ->
+is_b64_char(standard, $+) ->
+ true;
+is_b64_char(standard, $/) ->
+ true;
+is_b64_char(urlsafe, $-) ->
 true;
-is_b64_char($/) ->
+is_b64_char(urlsafe, $_) ->
 true;
-is_b64_char(C) when C >= $0, C =< $9 ->
+is_b64_char(_, C) when C >= $0, C =< $9 ->
 true;
-is_b64_char(C) when C >= $A, C =< $Z ->
+is_b64_char(_, C) when C >= $A, C =< $Z ->
 true;
-is_b64_char(C) when C >= $a, C =< $z ->
+is_b64_char(_, C) when C >= $a, C =< $z ->
 true;
-is_b64_char(_) ->
+is_b64_char(_, _) ->
 false.
 
 %% Check if the given argument is a base64 binary,
 %% ie that it consists of quadruplets of characters
 %% from the base64 alphabet, whereas the last quadruplet
 %% may be padded with one or two "="s
-is_b64_binary(B) ->
- is_b64_binary(B, 0).
+is_b64_binary(Mode, B) ->
+ is_b64_binary(Mode, B, 0).
 
-is_b64_binary(<<>>, N) ->
+is_b64_binary(_, <<>>, N) ->
 N rem 4 =:= 0;
-is_b64_binary(<<$=>>, N) ->
+is_b64_binary(_, <<$=>>, N) ->
 N rem 4 =:= 3;
-is_b64_binary(<<$=, $=>>, N) ->
+is_b64_binary(_, <<$=, $=>>, N) ->
 N rem 4 =:= 2;
-is_b64_binary(<<C, More/binary>>, N) ->
- case is_b64_char(C) of
+is_b64_binary(Mode, <<C, More/binary>>, N) ->
+ case is_b64_char(Mode, C) of
 true ->
- is_b64_binary(More, N + 1);
+ is_b64_binary(Mode, More, N + 1);
 false ->
 false
 end.
 
 %% Check if the given argument is a base64 string
 %% (see is_b64_binary/1)
-is_b64_string(S) ->
- is_b64_binary(list_to_binary(S)).
+is_b64_string(Mode, S) ->
+ is_b64_binary(Mode, list_to_binary(S)).
 
 %% Check if the argument is a list of bytes.
 is_bytelist(L) ->
@@ -349,23 +473,23 @@ str_equals(Str1, Str2) when is_binary(Str1), is_binary(Str2) ->
 %% Assumes that the given arguments are in a normalized form,
 %% ie that they consist only of characters from the base64
 %% alphabet and possible padding ("=").
-b64_equals(L, B) when is_list(L) ->
- b64_equals(list_to_binary(L), B);
-b64_equals(B, L) when is_list(L) ->
- b64_equals(B, list_to_binary(L));
-b64_equals(B1, B2) when is_binary(B1), is_binary(B2) ->
- b64_equals1(B1, B2).
-
-b64_equals1(<<Eq:4/bytes>>, <<Eq:4/bytes>>) ->
- is_b64_binary(Eq);
-b64_equals1(<<Eq:4/bytes, More1/binary>>, <<Eq:4/bytes, More2/binary>>) ->
- case lists:all(fun is_b64_char/1, binary_to_list(Eq)) of
+b64_equals(Mode, L, B) when is_list(L) ->
+ b64_equals(Mode, list_to_binary(L), B);
+b64_equals(Mode, B, L) when is_list(L) ->
+ b64_equals(Mode, B, list_to_binary(L));
+b64_equals(Mode, B1, B2) when is_binary(B1), is_binary(B2) ->
+ b64_equals1(Mode, B1, B2).
+
+b64_equals1(Mode, <<Eq:4/bytes>>, <<Eq:4/bytes>>) ->
+ is_b64_binary(Mode, Eq);
+b64_equals1(Mode, <<Eq:4/bytes, More1/binary>>, <<Eq:4/bytes, More2/binary>>) ->
+ case lists:all(fun(C) -> is_b64_char(Mode, C) end, binary_to_list(Eq)) of
 true ->
- b64_equals1(More1, More2);
+ b64_equals1(Mode, More1, More2);
 false ->
 false
 end;
-b64_equals1(<<Eq, B1, $=, $=>>, <<Eq, B2, $=, $=>>) ->
+b64_equals1(Mode, <<Eq, B1, $=, $=>>, <<Eq, B2, $=, $=>>) ->
 %% If the encoded string ends with "==", there exist multiple
 %% possibilities for the character preceding the "==" as only the
 %% 3rd and 4th bits of the encoded byte represented by that
@@ -374,7 +498,7 @@ b64_equals1(<<Eq, B1, $=, $=>>, <<Eq, B2, $=, $=>>) ->
 %% For example, all of the encoded strings "QQ==", "QR==", ..., "QZ=="
 %% decode to the string "A", since all the bytes represented by Q to Z
 %% are the same in the significant 3rd and 4th bit.
- case is_b64_char(Eq) of
+ case is_b64_char(Mode, Eq) of
 true ->
 Normalize = fun
 (C) when C >= $A, C =< $P -> $A;
@@ -383,20 +507,21 @@ b64_equals1(<<Eq, B1, $=, $=>>, <<Eq, B2, $=, $=>>) ->
 (C) when C >= $g, C =< $v -> $g;
 (C) when C >= $w, C =< $z -> $w;
 (C) when C >= $0, C =< $9 -> $w;
- ($+) -> $w;
- ($/) -> $w
+ ($+) when Mode =:= standard -> $w;
+ ($-) when Mode =:= urlsafe -> $w;
+ ($/) when Mode =:= standard -> $w;
+ ($_) when Mode =:= urlsafe -> $w
 end,
 Normalize(B1) =:= Normalize(B2);
 false ->
 false
 end;
-b64_equals1(<<Eq:2/bytes, B1, $=>>, <<Eq:2/bytes, B2, $=>>) ->
+b64_equals1(Mode, <<Eq1, Eq2, B1, $=>>, <<Eq1, Eq2, B2, $=>>) ->
 %% Similar to the above, but with the encoded string ending with a
 %% single "=" the 3rd to 6th bits of the encoded byte are significant,
 %% such that, for example, all the encoded strings "QUE=" to "QUH="
 %% decode to the same string "AA".
- <<Eq1, Eq2>> = Eq,
- case is_b64_char(Eq1) andalso is_b64_char(Eq2) of
+ case is_b64_char(Mode, Eq1) andalso is_b64_char(Mode, Eq2) of
 true ->
 Normalize = fun
 (C) when C >= $A, C =< $D -> $A;
@@ -416,14 +541,16 @@ b64_equals1(<<Eq:2/bytes, B1, $=>>, <<Eq:2/bytes, B2, $=>>) ->
 (C) when C >= $0, C =< $3 -> $0;
 (C) when C >= $4, C =< $7 -> $4;
 (C) when C >= $8, C =< $9 -> $8;
- ($+) -> $8;
- ($/) -> $8
+ ($+) when Mode =:= standard -> $8;
+ ($-) when Mode =:= urlsafe -> $8;
+ ($/) when Mode =:= standard -> $8;
+ ($_) when Mode =:= urlsafe -> $8
 end,
 Normalize(B1) =:= Normalize(B2);
 false ->
 false
 end;
-b64_equals1(<<>>, <<>>) ->
+b64_equals1(_, <<>>, <<>>) ->
 true;
-b64_equals1(_, _) ->
+b64_equals1(_, _, _) ->
 false.
-- 
2.35.3

Places

File 4241-base64-Add-selectable-alphabet.patch of Package erlang (Revision 3e53aa07e56d6cc0c5ffbbfd2f14b043)

Places