c2pa_io

Bounded random-access byte I/O used by the pure Dart C2PA packages. It provides memory sources and sinks on every Dart platform, RandomAccessFile adapters on the Dart VM, and browser Blob input.

Platforms

• Dart VM and Flutter: memory I/O plus package:c2pa_io/c2pa_io_vm.dart
• Web: memory I/O plus package:c2pa_io/c2pa_io_web.dart

import 'package:c2pa_io/c2pa_io.dart';

final source = MemoryByteSource([0x01, 0x02, 0x03]);
final bytes = await source.read(ByteRange(1, 3));

See example/c2pa_io.dart for a complete example.

Security and limits

Reads are range checked, exact-length, and copy their results. Coordinates are limited to JavaScript's exactly representable integer range. VM file sources detect length changes, while file sinks stage beside the destination before a filesystem rename; replacement atomicity follows the host filesystem. This package performs no network access.

Package relationships

c2pa_io is the lowest-level workspace package. c2pa_codec, c2pa_formats, c2pa_crypto, and c2pa build on these byte-source and sink interfaces.

Compatibility and limitations

The compatibility target is c2pa-rs c2pa-v0.90.22. This package provides I/O primitives, not C2PA parsing or validation. Browser support uses Blob; writable browser filesystem integration remains the application's responsibility.

Licensed under the MIT License (LICENSE). As an alternative, you may instead use this package under the Apache License, Version 2.0 (LICENSE-APACHE), so the package is offered as MIT OR Apache-2.0, at your option. Copyright is held by contributors to c2pa_dart.