download assets in build hook

pkgs/native_assets_cli/example/build/download_asset/hook/build.dart

@@ -2,18 +2,42 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:io';
+
 import 'package:download_asset/src/hook_helpers/c_build.dart';
+import 'package:download_asset/src/hook_helpers/download.dart';
+import 'package:native_assets_cli/code_assets_builder.dart';
 import 'package:native_assets_cli/native_assets_cli.dart';
 
 void main(List<String> args) async {
+  // TODO(https://github.com/dart-lang/native/issues/39): Use user-defines to
+  // control this instead.
   const localBuild = false;
 
   await build(args, (config, output) async {
     // ignore: dead_code
     if (localBuild) {
       await runBuild(config, output);
     } else {
-      // TODO(dcharkes): Download from GitHub.
+      final targetOS = config.codeConfig.targetOS;
+      final targetArchitecture = config.codeConfig.targetArchitecture;
+      final iOSSdk =
+          targetOS == OS.iOS ? config.codeConfig.iOSConfig.targetSdk : null;
+      final outputDirectory = Directory.fromUri(config.outputDirectory);
+      final file = await downloadAsset(
+        targetOS,
+        targetArchitecture,
+        iOSSdk,
+        outputDirectory,
+      );
+      output.codeAssets.add(CodeAsset(
+        package: config.packageName,
+        name: 'native_add.dart',
+        linkMode: DynamicLoadingBundled(),
+        os: targetOS,
+        architecture: targetArchitecture,
+        file: file.uri,
+      ));
     }
   });
 }

pkgs/native_assets_cli/example/build/download_asset/lib/src/hook_helpers/c_build.dart

@@ -7,15 +7,15 @@ import 'package:native_assets_cli/code_assets_builder.dart';
 import 'package:native_toolchain_c/native_toolchain_c.dart';
 
 Future<void> runBuild(BuildConfig config, BuildOutputBuilder output) async {
-  final target = createTargetName(
+  final name = createTargetName(
     config.codeConfig.targetOS.name,
     config.codeConfig.targetArchitecture.name,
     config.codeConfig.targetOS == OS.iOS
         ? config.codeConfig.iOSConfig.targetSdk.type
         : null,
   );
   final cbuilder = CBuilder.library(
-    name: 'native_add_$target',
+    name: name,
     assetName: 'native_add.dart',
     sources: [
       'src/native_add.c',
@@ -31,7 +31,7 @@ Future<void> runBuild(BuildConfig config, BuildOutputBuilder output) async {
 }
 
 String createTargetName(String osString, String architecture, String? iOSSdk) {
-  var targetName = '${osString}_$architecture';
+  var targetName = 'native_add_${osString}_$architecture';
   if (iOSSdk != null) {
     targetName += '_$iOSSdk';
   }

pkgs/native_assets_cli/example/build/download_asset/lib/src/hook_helpers/download.dart

@@ -0,0 +1,42 @@
+// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:io';
+
+import 'package:crypto/crypto.dart';
+import 'package:native_assets_cli/code_assets_builder.dart';
+
+import 'c_build.dart';
+import 'version.dart';
+
+Uri downloadUri(String target) => Uri.parse(
+    'https://github.com/dart-lang/native/releases/download/$version/$target');
+
+Future<File> downloadAsset(
+  OS targetOS,
+  Architecture targetArchitecture,
+  IOSSdk? iOSSdk,
+  Directory outputDirectory,
+) async {
+  final targetName = targetOS.dylibFileName(createTargetName(
+    targetOS.name,
+    targetArchitecture.name,
+    iOSSdk?.type,
+  ));
+  final uri = downloadUri(targetName);
+  final request = await HttpClient().getUrl(uri);
+  final response = await request.close();
+  if (response.statusCode != 200) {
+    throw ArgumentError('The request to $uri failed.');
+  }
+  final library = File.fromUri(outputDirectory.uri.resolve(targetName));
+  await library.create();
+  await response.pipe(library.openWrite());
+  return library;
+}
+
+Future<String> hashAsset(File assetFile) async {
+  final fileHash = md5.convert(await assetFile.readAsBytes()).toString();
+  return fileHash;
+}

pkgs/native_assets_cli/example/build/download_asset/lib/src/hook_helpers/hashes.dart

@@ -8,22 +8,24 @@
 //
 
 const assetHashes = <String, String>{
-  'android_arm': '2c38f3edc805a399dad866d619f9157d',
-  'android_arm64': 'c4f0d8c4c50d1e83592e499e7434b967',
-  'android_ia32': 'e3277144d97bd2c54beee581ed7e6665',
-  'android_riscv64': '8c2576cbe75c9a23f2532ff895f94f76',
-  'android_x64': '9a7bec53e1591091669ecd2bd20911d1',
-  'ios_arm64_iphoneos': 'e9a4d8b4d47efc05da36c7b05991d174',
-  'ios_arm64_iphonesimulator': 'a745567274206e879a267c4f6ab998db',
-  'ios_x64_iphonesimulator': '6568ce774690893512c108bb4e2d1974',
-  'linux_arm': '1a5b9e4b459e13ee85c148582b9b2252',
-  'linux_arm64': '2b3d736e0c0ac1e1537bc43bd9b82cad',
-  'linux_ia32': 'ed6e130e53fa18eab5572ed106cdaab1',
-  'linux_riscv64': '7fa82325ba7803a0443ca27e3300e7f9',
-  'linux_x64': 'f7af8d1547cdfb150a73d513a7957999',
-  'macos_arm64': '075398c86f0a13f0ee166bc8aaf1e41a',
-  'macos_x64': 'ed56424be52561da5a57d3f5af837ce2',
-  'windows_arm64': 'c0a52c089afa52f6532717c4c91e904f',
-  'windows_ia32': '70b7c31e4546764618600f380a0db869',
-  'windows_x64': '73d2f8f4daf35111370a8a6fa380ac69',
+  'libnative_add_android_arm.so': '2c38f3edc805a399dad866d619f9157d',
+  'libnative_add_android_arm64.so': 'c4f0d8c4c50d1e83592e499e7434b967',
+  'libnative_add_android_ia32.so': 'e3277144d97bd2c54beee581ed7e6665',
+  'libnative_add_android_riscv64.so': '8c2576cbe75c9a23f2532ff895f94f76',
+  'libnative_add_android_x64.so': '9a7bec53e1591091669ecd2bd20911d1',
+  'libnative_add_ios_arm64_iphoneos.dylib': '1bf1473cacb7fd2778fc5bb28f0b61a2',
+  'libnative_add_ios_arm64_iphonesimulator.dylib':
+      'cdddffc0787e6a3a846affcb05fac3a8',
+  'libnative_add_ios_x64_iphonesimulator.dylib':
+      '4aea6d631350540d50452ac2bdd1a422',
+  'libnative_add_linux_arm.so': '1a5b9e4b459e13ee85c148582b9b2252',
+  'libnative_add_linux_arm64.so': '2b3d736e0c0ac1e1537bc43bd9b82cad',
+  'libnative_add_linux_ia32.so': 'ed6e130e53fa18eab5572ed106cdaab1',
+  'libnative_add_linux_riscv64.so': '7fa82325ba7803a0443ca27e3300e7f9',
+  'libnative_add_linux_x64.so': 'f7af8d1547cdfb150a73d513a7957999',
+  'libnative_add_macos_arm64.dylib': 'f0804ff4b55126996c180114f25ca5bd',
+  'libnative_add_macos_x64.dylib': 'b62263803dceb3c23508cb909b5a5583',
+  'native_add_windows_arm64.dll': '7aa6f5e0275ba1b94cd5b7356f89ef04',
+  'native_add_windows_ia32.dll': 'ab57b5504d92b5b5dc09732d990fd5e7',
+  'native_add_windows_x64.dll': 'be9ba2125800aa2e3481a759b1845a50',
 };

pkgs/native_assets_cli/example/build/download_asset/lib/src/hook_helpers/targets.dart

@@ -0,0 +1,31 @@
+// Copyright (c, null) 2025, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// THIS FILE IS AUTOGENERATED. TO UPDATE, RUN
+//
+//    dart --enable-experiment=native-assets tool/generate_asset_hashes.dart
+//
+
+import 'package:native_assets_cli/code_assets_builder.dart';
+
+const supportedTargets = [
+  (OS.android, Architecture.arm, null),
+  (OS.android, Architecture.arm64, null),
+  (OS.android, Architecture.ia32, null),
+  (OS.android, Architecture.riscv64, null),
+  (OS.android, Architecture.x64, null),
+  (OS.iOS, Architecture.arm64, IOSSdk.iPhoneOS),
+  (OS.iOS, Architecture.arm64, IOSSdk.iPhoneSimulator),
+  (OS.iOS, Architecture.x64, IOSSdk.iPhoneSimulator),
+  (OS.linux, Architecture.arm, null),
+  (OS.linux, Architecture.arm64, null),
+  (OS.linux, Architecture.ia32, null),
+  (OS.linux, Architecture.riscv64, null),
+  (OS.linux, Architecture.x64, null),
+  (OS.macOS, Architecture.arm64, null),
+  (OS.macOS, Architecture.x64, null),
+  (OS.windows, Architecture.arm64, null),
+  (OS.windows, Architecture.ia32, null),
+  (OS.windows, Architecture.x64, null),
+];

pkgs/native_assets_cli/example/build/download_asset/lib/src/hook_helpers/version.dart

@@ -0,0 +1,13 @@
+// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'download.dart';
+import 'hashes.dart';
+
+/// The GitHub release to use for downloading assets.
+///
+/// Assets are downloaded from [downloadUri].
+///
+/// After changing [assetHashes] must be updated.
+const version = 'download_asset-prebuild-assets-v0.1.0-try-3';

pkgs/native_assets_cli/example/build/download_asset/pubspec.yaml

@@ -9,6 +9,7 @@ environment:
   sdk: '>=3.3.0 <4.0.0'
 
 dependencies:
+  crypto: ^3.0.3
   logging: ^1.1.1
   native_assets_cli: ^0.10.0
   # native_assets_cli:
@@ -19,7 +20,6 @@ dependencies:
 
 dev_dependencies:
   args: ^2.6.0
-  crypto: ^3.0.3
   ffigen: ^8.0.2
   lints: ^3.0.0
   test: ^1.21.0

pkgs/native_assets_cli/example/build/download_asset/tool/build.dart

@@ -6,7 +6,7 @@ import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:download_asset/src/hook_helpers/c_build.dart';
-import 'package:download_asset/src/hook_helpers/versions.dart';
+import 'package:download_asset/src/hook_helpers/target_versions.dart';
 import 'package:native_assets_cli/code_assets_builder.dart';
 
 void main(List<String> args) async {

pkgs/native_assets_cli/example/build/download_asset/tool/generate_asset_hashes.dart

@@ -4,24 +4,29 @@
 
 import 'dart:io';
 
-import 'package:crypto/crypto.dart';
+import 'package:download_asset/src/hook_helpers/download.dart';
+import 'package:download_asset/src/hook_helpers/hashes.dart';
+import 'package:download_asset/src/hook_helpers/targets.dart';
 
-// TODO(dcharkes): Change this to download the files from GitHub releases,
-// and run it manually _after_ a GitHub release before releasing a new build
-// hook that uses the new assets.
+/// Regenerates [assetHashes].
 Future<void> main(List<String> args) async {
   final assetsDir = Directory.fromUri(
       Platform.script.resolve('../.dart_tool/download_asset/'));
+  await assetsDir.delete(recursive: true);
+  await assetsDir.create(recursive: true);
+  await Future.wait([
+    for (final (targetOS, targetArchitecture, iOSSdk) in supportedTargets)
+      downloadAsset(targetOS, targetArchitecture, iOSSdk, assetsDir),
+  ]);
   final assetFiles = assetsDir
       .listSync(recursive: true)
       .whereType<File>()
       .toList()
     ..sort((f1, f2) => f1.path.compareTo(f2.path));
   final assetHashes = <String, String>{};
   for (final assetFile in assetFiles) {
-    final fileHash = md5.convert(await assetFile.readAsBytes()).toString();
-    final target =
-        assetFile.uri.resolve('.').pathSegments.lastWhere((e) => e.isNotEmpty);
+    final fileHash = await hashAsset(assetFile);
+    final target = assetFile.uri.pathSegments.lastWhere((e) => e.isNotEmpty);
     assetHashes[target] = fileHash;
   }