Simplify base64 streaming decoder, drop decoding check.
BUG=
R=sgjesse@google.com
Review URL: https://codereview.chromium.org//1255293010 .
diff --git a/lib/src/base64.dart b/lib/src/base64.dart
index 00ff11e..b4c03a8 100644
--- a/lib/src/base64.dart
+++ b/lib/src/base64.dart
@@ -30,9 +30,6 @@
const String _encodeTable =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
-const List<String> _URL_SAFE_CHARACTERS = const ['+', '/'];
-const List<String> _URL_UNSAFE_CHARACTERS = const ['-', '_'];
-
const int _LINE_LENGTH = 76;
const int _CR = 13; // '\r'
const int _LF = 10; // '\n'
@@ -284,9 +281,6 @@
return new List<int>(0);
}
- bool expectedSafe = false;
- bool expectedUnsafe = false;
-
int normalLength = 0;
int i = 0;
// Count '\r', '\n' and illegal characters, check if
@@ -306,20 +300,6 @@
} else {
throw new FormatException('Invalid character', input, i);
}
- } else if (input[i] == _URL_UNSAFE_CHARACTERS[0] ||
- input[i] == _URL_UNSAFE_CHARACTERS[1]) {
-
- if (expectedSafe) {
- throw new FormatException('Unsafe character in URL-safe string',
- input, i);
- }
- expectedUnsafe = true;
- } else if (input[i] == _URL_SAFE_CHARACTERS[0] ||
- input[i] == _URL_SAFE_CHARACTERS[1]) {
- if (expectedUnsafe) {
- throw new FormatException('Invalid character', input, i);
- }
- expectedSafe = true;
}
if (c >= 0) normalLength++;
i++;
@@ -384,83 +364,33 @@
final Base64Decoder _decoder = new Base64Decoder();
final ChunkedConversionSink<List<int>> _outSink;
- String _buffer = "";
- bool _isSafe = false;
- bool _isUnsafe = false;
- int _expectPaddingCount = 3;
+ String _unconverted = "";
_Base64DecoderSink(this._outSink);
void add(String chunk) {
if (chunk.isEmpty) return;
-
- int nextBufferLength = (chunk.length + _buffer.length) % 4;
-
- if (chunk.length >= _expectPaddingCount &&
- chunk.substring(0, _expectPaddingCount) ==
- _ENCODED_PAD.substring(3 - _expectPaddingCount, 3)) {
- chunk = _PAD + chunk.substring(_expectPaddingCount);
- _expectPaddingCount = 3;
- } else if(chunk.length < _expectPaddingCount &&
- chunk == _ENCODED_PAD.substring(
- 3 - _expectPaddingCount,
- 3 - _expectPaddingCount + chunk.length)) {
- _expectPaddingCount -= chunk.length;
- chunk = "";
+ if (_unconverted.isNotEmpty) {
+ chunk = _unconverted + chunk;
}
-
- if (chunk.length > 1 &&
- chunk[chunk.length - 2] == _ENCODED_PAD[0] &&
- chunk[chunk.length - 1] == _ENCODED_PAD[1]) {
- _expectPaddingCount = 1;
- chunk = chunk.substring(0, chunk.length - 2);
- } else if (!chunk.isEmpty && chunk[chunk.length - 1] == _ENCODED_PAD[0]) {
- _expectPaddingCount = 2;
- chunk = chunk.substring(0, chunk.length - 1);
- }
-
chunk = chunk.replaceAll(_ENCODED_PAD, _PAD);
-
- if (chunk.length + _buffer.length >= 4) {
- int remainder = chunk.length - nextBufferLength;
- String decodable = _buffer + chunk.substring(0, remainder);
- _buffer = chunk.substring(remainder);
-
- for (int i = 0;i < decodable.length; i++) {
- if (decodable[i] == _URL_UNSAFE_CHARACTERS[0] ||
- decodable[i] == _URL_UNSAFE_CHARACTERS[1]) {
- if (_isSafe) {
- throw new FormatException('Unsafe character in URL-safe string',
- decodable, i);
- }
- _isUnsafe = true;
- } else if (decodable[i] == _URL_SAFE_CHARACTERS[0] ||
- decodable[i] == _URL_SAFE_CHARACTERS[1]) {
- if (_isUnsafe) {
- throw new FormatException('Invalid character', decodable, i);
- }
- _isSafe = true;
- }
- }
-
- _outSink.add(_decoder.convert(decodable));
- } else {
- _buffer += chunk;
+ int decodableLength = chunk.length;
+ // If chunk ends in "%" or "%3", it may be a partial encoded pad.
+ // If chunk is smaller than 4 characters, don't bother checking.
+ if (chunk.length > 3 &&
+ chunk.contains(_ENCODED_PAD[0], chunk.length - 2)) {
+ decodableLength = chunk.lastIndexOf(_ENCODED_PAD[0]);
+ }
+ decodableLength -= decodableLength % 4;
+ _unconverted = chunk.substring(decodableLength);
+ if (decodableLength > 0) {
+ _outSink.add(_decoder.convert(chunk.substring(0, decodableLength)));
}
}
void close() {
- if (_expectPaddingCount == 0 &&
- _buffer.length == 3) {
- _outSink.add(_buffer + _PAD);
- } else if (_expectPaddingCount < 3 &&
- _buffer.length + 3 - _expectPaddingCount == 4) {
- _outSink.add(_buffer + _ENCODED_PAD.substring(0, 3 - _expectPaddingCount));
- } else if (_expectPaddingCount != 3 || !_buffer.isEmpty) {
- throw new FormatException(
- "Size of Base 64 input must be a multiple of 4",
- _buffer + _PAD.substring(0, 3 - _expectPaddingCount),
- _buffer.length + 3 - _expectPaddingCount);
+ if (_unconverted.isNotEmpty) {
+ _outSink.add(_decoder.convert(_unconverted));
}
_outSink.close();
}
diff --git a/test/base64_test.dart b/test/base64_test.dart
index 76b586e..879239b 100644
--- a/test/base64_test.dart
+++ b/test/base64_test.dart
@@ -17,8 +17,6 @@
test('decoder for malformed input', _testDecoderForMalformedInput);
test('encode decode lists', _testEncodeDecodeLists);
test('url safe encode-decode', _testUrlSafeEncodeDecode);
- test('consistent safe/unsafe character decoding',
- _testConsistentSafeUnsafeDecode);
test('percent-encoded padding character encode-decode',
_testPaddingCharacter);
test('streaming encoder', _testStreamingEncoder);
@@ -29,8 +27,6 @@
_testStreamingEncoderForDecompositions);
test('streaming decoder for different decompositions of a string',
_testStreamingDecoderForDecompositions);
- test('consistent safe/unsafe character streaming decoding',
- _testConsistentSafeUnsafeStreamDecode);
test('streaming for encoded padding character',
_testStreamingForEncodedPadding);
test('old api', _testOldApi);
@@ -84,10 +80,6 @@
const _DECOMPOSITION_ENCODED = 'xBCexA==';
-const _INCONSISTENT_SAFE_RESULT = 'A+_x';
-
-const _INCONSISTENT_SAFE_STREAMING_RESULT = const ['A+AAA', '_x='];
-
// Test data with only zeroes.
var inputsWithZeroes = [[0, 0, 0], [0, 0], [0], []];
const _RESULTS_WITH_ZEROS = const ['AAAA', 'AAA=', 'AA==', ''];
@@ -237,19 +229,6 @@
expect(streamedResult, encUrlSafe);
}
-void _testConsistentSafeUnsafeDecode() {
- expect(() {
- BASE64.decode(_INCONSISTENT_SAFE_RESULT);
- }, throwsFormatException);
-}
-
-Future _testConsistentSafeUnsafeStreamDecode() {
- expect(new Stream.fromIterable(_INCONSISTENT_SAFE_STREAMING_RESULT)
- .transform(BASE64.decoder)
- .toList(),
- throwsFormatException);
-}
-
Future _testStreamingForEncodedPadding() async {
List<String> withEncodedPadding = ['AA%', '3D', '%', '3', 'DEFGZ'];
List<int> decoded = BASE64.decode('AA==EFGZ');
