Fix bigIntToBytes: non-growable list and broken comparisons#28
Merged
Harry-Chen merged 2 commits intonfcim:masterfrom Mar 13, 2026
Merged
Fix bigIntToBytes: non-growable list and broken comparisons#28Harry-Chen merged 2 commits intonfcim:masterfrom
Harry-Chen merged 2 commits intonfcim:masterfrom
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@klaasdannen Thank you very much for all the fixes! Please rebase this PR to master and run |
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Pull request overview
This PR fixes ByteUtils.bigIntToBytes() so it no longer crashes at runtime when appending bytes, and corrects BigInt overflow checking and endianness reversal behavior.
Changes:
- Replace invalid/non-growable list initialization with a growable
List<int>and convert viaUint8List.fromList. - Fix overflow check by using
BigInt.zeroand improve reversal by materializing.reversedinto aList. - Add a concrete type annotation to the
endiannessparameter.
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| var list = <int>[]; | ||
| BigInt v = value!; |
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| for (int i = 0; i < length; i++) { | ||
| list.add((v! % (BigInt.from(256))).toInt()); | ||
| v ~/= (BigInt.from(256)); | ||
| list.add((v % BigInt.from(256)).toInt()); | ||
| v ~/= BigInt.from(256); |
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| if (v != BigInt.zero) { | ||
| throw ArgumentError("Value $value is overflow from range of $length bytes"); | ||
| } |
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| static Uint8List bigIntToBytes( | ||
| BigInt? value, | ||
| int length, { | ||
| endianness = Endianness.Big, | ||
| Endianness endianness = Endianness.Big, | ||
| }) { | ||
| Uint8List? list = List<int?>.filled(0, null, growable: false) as Uint8List; | ||
| BigInt? v = value; | ||
| var list = <int>[]; | ||
| BigInt v = value!; | ||
| for (int i = 0; i < length; i++) { | ||
| list.add((v! % (BigInt.from(256))).toInt()); | ||
| v ~/= (BigInt.from(256)); | ||
| list.add((v % BigInt.from(256)).toInt()); | ||
| v ~/= BigInt.from(256); | ||
| } | ||
|
|
||
| /// unrelated_type_equality_check checked! | ||
| BigInt zero = 0 as BigInt; | ||
| if (v != zero) { | ||
| throw "Value $value is overflow from range of $length bytes"; | ||
| if (v != BigInt.zero) { | ||
| throw ArgumentError("Value $value is overflow from range of $length bytes"); | ||
| } | ||
| if (endianness == Endianness.Big) { | ||
| list = list.reversed as Uint8List?; | ||
| list = list.reversed.toList(); | ||
| } | ||
| return Uint8List.fromList(list!); | ||
| return Uint8List.fromList(list); |
The method created a non-growable List<int?>.filled(0, null, growable: false) then cast it to Uint8List and called .add() on it, which crashes at runtime. Also fixed: invalid cast of int 0 to BigInt for overflow check, missing type annotation on endianness parameter, and .reversed producing an Iterable being cast directly to Uint8List instead of converting to List first.
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Summary
bigIntToBytes()created a non-growableList<int?>.filled(0, null, growable: false)then cast it toUint8Listand called.add(), which crashes at runtime with aRangeError0 as BigIntis an invalid cast, replaced withBigInt.zero.reversedreturns anIterable, notUint8List-- now uses.reversed.toList()endiannessparameterTest plan
test/ndef_test.dartcontinue to passBigIntround-trip encoding/decoding works for values that exercise this path (e.g., Signature records)