Native assets support for Linux (#134031)

Support for FFI calls with `@Native external` functions through Native assets on Linux. This enables bundling native code without any build-system boilerplate code.

For more info see:

* https://github.com/flutter/flutter/issues/129757

### Implementation details for Linux.

Mainly follows the design of https://github.com/flutter/flutter/pull/130494.

Some differences are:

* Linux does not support cross compiling or compiling for multiple architectures, so this has not been implemented.
* Linux has no add2app.

The assets copying is done in the install-phase of the CMake build of a flutter app.
CMake requires the native assets folder to exist, so we create it also when the feature is disabled or there are no assets.

### Tests

This PR adds new tests to cover the various use cases.

* packages/flutter_tools/test/general.shard/linux/native_assets_test.dart
  * Unit tests the Linux-specific part of building native assets.

It also extends various existing tests:

* packages/flutter_tools/test/integration.shard/native_assets_test.dart
  * Runs (incl hot reload/hot restart), builds, builds frameworks for Linux and flutter-tester.

.ci.yaml

@@ -951,8 +951,10 @@ targets:
           {"dependency": "android_sdk", "version": "version:33v6"},
           {"dependency": "chrome_and_driver", "version": "version:115.0"},
           {"dependency": "clang", "version": "git_revision:5d5aba78dbbee75508f01bcaa69aedb2ab79065a"},
-          {"dependency": "open_jdk", "version": "version:11"},
-          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"}
+          {"dependency": "cmake", "version": "build_id:8787856497187628321"},
+          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"},
+          {"dependency": "ninja", "version": "version:1.9.0"},
+          {"dependency": "open_jdk", "version": "version:11"}
         ]
       shard: tool_integration_tests
       subshard: "1_4"
@@ -975,8 +977,10 @@ targets:
           {"dependency": "android_sdk", "version": "version:33v6"},
           {"dependency": "chrome_and_driver", "version": "version:115.0"},
           {"dependency": "clang", "version": "git_revision:5d5aba78dbbee75508f01bcaa69aedb2ab79065a"},
-          {"dependency": "open_jdk", "version": "version:11"},
-          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"}
+          {"dependency": "cmake", "version": "build_id:8787856497187628321"},
+          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"},
+          {"dependency": "ninja", "version": "version:1.9.0"},
+          {"dependency": "open_jdk", "version": "version:11"}
         ]
       shard: tool_integration_tests
       subshard: "2_4"
@@ -999,8 +1003,10 @@ targets:
           {"dependency": "android_sdk", "version": "version:33v6"},
           {"dependency": "chrome_and_driver", "version": "version:115.0"},
           {"dependency": "clang", "version": "git_revision:5d5aba78dbbee75508f01bcaa69aedb2ab79065a"},
-          {"dependency": "open_jdk", "version": "version:11"},
-          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"}
+          {"dependency": "cmake", "version": "build_id:8787856497187628321"},
+          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"},
+          {"dependency": "ninja", "version": "version:1.9.0"},
+          {"dependency": "open_jdk", "version": "version:11"}
         ]
       shard: tool_integration_tests
       subshard: "3_4"
@@ -1023,8 +1029,10 @@ targets:
           {"dependency": "android_sdk", "version": "version:33v6"},
           {"dependency": "chrome_and_driver", "version": "version:115.0"},
           {"dependency": "clang", "version": "git_revision:5d5aba78dbbee75508f01bcaa69aedb2ab79065a"},
-          {"dependency": "open_jdk", "version": "version:11"},
-          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"}
+          {"dependency": "cmake", "version": "build_id:8787856497187628321"},
+          {"dependency": "goldctl", "version": "git_revision:f808dcff91b221ae313e540c09d79696cd08b8de"},
+          {"dependency": "ninja", "version": "version:1.9.0"},
+          {"dependency": "open_jdk", "version": "version:11"}
         ]
       shard: tool_integration_tests
       subshard: "4_4"

packages/flutter_tools/lib/src/build_system/targets/native_assets.dart

@@ -12,6 +12,7 @@ import '../../base/platform.dart';
 import '../../build_info.dart';
 import '../../dart/package_map.dart';
 import '../../ios/native_assets.dart';
+import '../../linux/native_assets.dart';
 import '../../macos/native_assets.dart';
 import '../../macos/xcode.dart';
 import '../../native_assets.dart';
@@ -118,6 +119,21 @@ class NativeAssets extends Target {
           fileSystem: fileSystem,
           buildRunner: buildRunner,
         );
+      case TargetPlatform.linux_arm64:
+      case TargetPlatform.linux_x64:
+        final String? environmentBuildMode = environment.defines[kBuildMode];
+        if (environmentBuildMode == null) {
+          throw MissingDefineException(kBuildMode, name);
+        }
+        final BuildMode buildMode = BuildMode.fromCliName(environmentBuildMode);
+        (_, dependencies) = await buildNativeAssetsLinux(
+          targetPlatform: targetPlatform,
+          buildMode: buildMode,
+          projectUri: projectUri,
+          yamlParentDirectory: environment.buildDir.uri,
+          fileSystem: fileSystem,
+          buildRunner: buildRunner,
+        );
       case TargetPlatform.tester:
         if (const LocalPlatform().isMacOS) {
           (_, dependencies) = await buildNativeAssetsMacOS(
@@ -129,6 +145,15 @@ class NativeAssets extends Target {
             buildRunner: buildRunner,
             flutterTester: true,
           );
+        } else if (const LocalPlatform().isLinux) {
+          (_, dependencies) = await buildNativeAssetsLinux(
+            buildMode: BuildMode.debug,
+            projectUri: projectUri,
+            yamlParentDirectory: environment.buildDir.uri,
+            fileSystem: fileSystem,
+            buildRunner: buildRunner,
+            flutterTester: true,
+          );
         } else {
           // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757
           // Write the file we claim to have in the [outputs].
@@ -142,8 +167,6 @@ class NativeAssets extends Target {
       case TargetPlatform.android:
       case TargetPlatform.fuchsia_arm64:
       case TargetPlatform.fuchsia_x64:
-      case TargetPlatform.linux_arm64:
-      case TargetPlatform.linux_x64:
       case TargetPlatform.web_javascript:
       case TargetPlatform.windows_x64:
         // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757

packages/flutter_tools/lib/src/linux/build_linux.dart

@@ -17,6 +17,7 @@ import '../convert.dart';
 import '../flutter_plugins.dart';
 import '../globals.dart' as globals;
 import '../migrations/cmake_custom_command_migration.dart';
+import '../migrations/cmake_native_assets_migration.dart';
 
 // Matches the following error and warning patterns:
 // - <file path>:<line>:<column>: (fatal) error: <error...>
@@ -45,6 +46,7 @@ Future<void> buildLinux(
 
   final List<ProjectMigrator> migrators = <ProjectMigrator>[
     CmakeCustomCommandMigration(linuxProject, logger),
+    CmakeNativeAssetsMigration(linuxProject, 'linux', logger),
   ];
 
   final ProjectMigration migration = ProjectMigration(migrators);

packages/flutter_tools/lib/src/linux/native_assets.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:native_assets_builder/native_assets_builder.dart' show BuildResult;
+import 'package:native_assets_cli/native_assets_cli.dart' hide BuildMode;
+import 'package:native_assets_cli/native_assets_cli.dart' as native_assets_cli;
+
+import '../base/common.dart';
+import '../base/file_system.dart';
+import '../base/io.dart';
+import '../build_info.dart';
+import '../globals.dart' as globals;
+import '../native_assets.dart';
+
+/// Dry run the native builds.
+///
+/// This does not build native assets, it only simulates what the final paths
+/// of all assets will be so that this can be embedded in the kernel file.
+Future<Uri?> dryRunNativeAssetsLinux({
+  required NativeAssetsBuildRunner buildRunner,
+  required Uri projectUri,
+  bool flutterTester = false,
+  required FileSystem fileSystem,
+}) async {
+  if (await hasNoPackageConfig(buildRunner) || await isDisabledAndNoNativeAssets(buildRunner)) {
+    return null;
+  }
+
+  final Uri buildUri_ = nativeAssetsBuildUri(projectUri, OS.linux);
+  final Iterable<Asset> nativeAssetPaths = await dryRunNativeAssetsLinuxInternal(
+    fileSystem,
+    projectUri,
+    flutterTester,
+    buildRunner,
+  );
+  final Uri nativeAssetsUri = await writeNativeAssetsYaml(
+    nativeAssetPaths,
+    buildUri_,
+    fileSystem,
+  );
+  return nativeAssetsUri;
+}
+
+Future<Iterable<Asset>> dryRunNativeAssetsLinuxInternal(
+  FileSystem fileSystem,
+  Uri projectUri,
+  bool flutterTester,
+  NativeAssetsBuildRunner buildRunner,
+) async {
+  const OS targetOs = OS.linux;
+  final Uri buildUri_ = nativeAssetsBuildUri(projectUri, targetOs);
+
+  globals.logger.printTrace('Dry running native assets for $targetOs.');
+  final List<Asset> nativeAssets = (await buildRunner.dryRun(
+    linkModePreference: LinkModePreference.dynamic,
+    targetOs: targetOs,
+    workingDirectory: projectUri,
+    includeParentEnvironment: true,
+  ))
+      .assets;
+  ensureNoLinkModeStatic(nativeAssets);
+  globals.logger.printTrace('Dry running native assets for $targetOs done.');
+  final Uri? absolutePath = flutterTester ? buildUri_ : null;
+  final Map<Asset, Asset> assetTargetLocations = _assetTargetLocations(nativeAssets, absolutePath);
+  final Iterable<Asset> nativeAssetPaths = assetTargetLocations.values;
+  return nativeAssetPaths;
+}
+
+/// Builds native assets.
+///
+/// If [targetPlatform] is omitted, the current target architecture is used.
+///
+/// If [flutterTester] is true, absolute paths are emitted in the native
+/// assets mapping. This can be used for JIT mode without sandbox on the host.
+/// This is used in `flutter test` and `flutter run -d flutter-tester`.
+Future<(Uri? nativeAssetsYaml, List<Uri> dependencies)> buildNativeAssetsLinux({
+  required NativeAssetsBuildRunner buildRunner,
+  TargetPlatform? targetPlatform,
+  required Uri projectUri,
+  required BuildMode buildMode,
+  bool flutterTester = false,
+  Uri? yamlParentDirectory,
+  required FileSystem fileSystem,
+}) async {
+  const OS targetOs = OS.linux;
+  final Uri buildUri_ = nativeAssetsBuildUri(projectUri, targetOs);
+  final Directory buildDir = fileSystem.directory(buildUri_);
+  if (!await buildDir.exists()) {
+    // CMake requires the folder to exist to do copying.
+    await buildDir.create(recursive: true);
+  }
+  if (await hasNoPackageConfig(buildRunner) || await isDisabledAndNoNativeAssets(buildRunner)) {
+    final Uri nativeAssetsYaml = await writeNativeAssetsYaml(<Asset>[], yamlParentDirectory ?? buildUri_, fileSystem);
+    return (nativeAssetsYaml, <Uri>[]);
+  }
+
+  final Target target = targetPlatform != null ? _getNativeTarget(targetPlatform) : Target.current;
+  final native_assets_cli.BuildMode buildModeCli = nativeAssetsBuildMode(buildMode);
+
+  globals.logger.printTrace('Building native assets for $target $buildModeCli.');
+  final BuildResult result = await buildRunner.build(
+    linkModePreference: LinkModePreference.dynamic,
+    target: target,
+    buildMode: buildModeCli,
+    workingDirectory: projectUri,
+    includeParentEnvironment: true,
+    cCompilerConfig: await buildRunner.cCompilerConfig,
+  );
+  final List<Asset> nativeAssets = result.assets;
+  final Set<Uri> dependencies = result.dependencies.toSet();
+  ensureNoLinkModeStatic(nativeAssets);
+  globals.logger.printTrace('Building native assets for $target done.');
+  final Uri? absolutePath = flutterTester ? buildUri_ : null;
+  final Map<Asset, Asset> assetTargetLocations = _assetTargetLocations(nativeAssets, absolutePath);
+  await _copyNativeAssetsLinux(
+    buildUri_,
+    assetTargetLocations,
+    buildMode,
+    fileSystem,
+  );
+  final Uri nativeAssetsUri = await writeNativeAssetsYaml(
+    assetTargetLocations.values,
+    yamlParentDirectory ?? buildUri_,
+    fileSystem,
+  );
+  return (nativeAssetsUri, dependencies.toList());
+}
+
+Map<Asset, Asset> _assetTargetLocations(
+  List<Asset> nativeAssets,
+  Uri? absolutePath,
+) =>
+    <Asset, Asset>{
+      for (final Asset asset in nativeAssets) asset: _targetLocationLinux(asset, absolutePath),
+    };
+
+Asset _targetLocationLinux(Asset asset, Uri? absolutePath) {
+  final AssetPath path = asset.path;
+  switch (path) {
+    case AssetSystemPath _:
+    case AssetInExecutable _:
+    case AssetInProcess _:
+      return asset;
+    case AssetAbsolutePath _:
+      final String fileName = path.uri.pathSegments.last;
+      Uri uri;
+      if (absolutePath != null) {
+        // Flutter tester needs full host paths.
+        uri = absolutePath.resolve(fileName);
+      } else {
+        // Flutter Desktop needs "absolute" paths inside the app.
+        // "relative" in the context of native assets would be relative to the
+        // kernel or aot snapshot.
+        uri = Uri(path: fileName);
+      }
+      return asset.copyWith(path: AssetAbsolutePath(uri));
+  }
+  throw Exception('Unsupported asset path type ${path.runtimeType} in asset $asset');
+}
+
+/// Extract the [Target] from a [TargetPlatform].
+Target _getNativeTarget(TargetPlatform targetPlatform) {
+  switch (targetPlatform) {
+    case TargetPlatform.linux_x64:
+      return Target.linuxX64;
+    case TargetPlatform.linux_arm64:
+      return Target.linuxArm64;
+    case TargetPlatform.android:
+    case TargetPlatform.ios:
+    case TargetPlatform.darwin:
+    case TargetPlatform.windows_x64:
+    case TargetPlatform.fuchsia_arm64:
+    case TargetPlatform.fuchsia_x64:
+    case TargetPlatform.tester:
+    case TargetPlatform.web_javascript:
+    case TargetPlatform.android_arm:
+    case TargetPlatform.android_arm64:
+    case TargetPlatform.android_x64:
+    case TargetPlatform.android_x86:
+      throw Exception('Unknown targetPlatform: $targetPlatform.');
+  }
+}
+
+Future<void> _copyNativeAssetsLinux(
+  Uri buildUri,
+  Map<Asset, Asset> assetTargetLocations,
+  BuildMode buildMode,
+  FileSystem fileSystem,
+) async {
+  if (assetTargetLocations.isNotEmpty) {
+    globals.logger.printTrace('Copying native assets to ${buildUri.toFilePath()}.');
+    final Directory buildDir = fileSystem.directory(buildUri.toFilePath());
+    if (!buildDir.existsSync()) {
+      buildDir.createSync(recursive: true);
+    }
+    for (final MapEntry<Asset, Asset> assetMapping in assetTargetLocations.entries) {
+      final Uri source = (assetMapping.key.path as AssetAbsolutePath).uri;
+      final Uri target = (assetMapping.value.path as AssetAbsolutePath).uri;
+      final Uri targetUri = buildUri.resolveUri(target);
+      final String targetFullPath = targetUri.toFilePath();
+      await fileSystem.file(source).copy(targetFullPath);
+    }
+    globals.logger.printTrace('Copying native assets done.');
+  }
+}
+
+/// Flutter expects `clang++` to be on the path on Linux hosts.
+///
+/// Search for the accompanying `clang`, `ar`, and `ld`.
+Future<CCompilerConfig> cCompilerConfigLinux() async {
+  const String kClangPlusPlusBinary = 'clang++';
+  const String kClangBinary = 'clang';
+  const String kArBinary = 'llvm-ar';
+  const String kLdBinary = 'ld.lld';
+
+  final ProcessResult whichResult = await globals.processManager.run(<String>['which', kClangPlusPlusBinary]);
+  if (whichResult.exitCode != 0) {
+    throwToolExit('Failed to find $kClangPlusPlusBinary on PATH.');
+  }
+  File clangPpFile = globals.fs.file((whichResult.stdout as String).trim());
+  clangPpFile = globals.fs.file(await clangPpFile.resolveSymbolicLinks());
+
+  final Directory clangDir = clangPpFile.parent;
+  final Map<String, Uri> binaryPaths = <String, Uri>{};
+  for (final String binary in <String>[kClangBinary, kArBinary, kLdBinary]) {
+    final File binaryFile = clangDir.childFile(binary);
+    if (!await binaryFile.exists()) {
+      throwToolExit("Failed to find $binary relative to $clangPpFile: $binaryFile doesn't exist.");
+    }
+    binaryPaths[binary] = binaryFile.uri;
+  }
+  return CCompilerConfig(
+    ar: binaryPaths[kArBinary],
+    cc: binaryPaths[kClangBinary],
+    ld: binaryPaths[kLdBinary],
+  );
+}

packages/flutter_tools/lib/src/migrations/cmake_native_assets_migration.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../base/file_system.dart';
+import '../base/project_migrator.dart';
+import '../cmake_project.dart';
+
+/// Adds the snippet to the CMake file that copies the native assets.
+///
+/// ```cmake
+/// # Copy the native assets provided by the build.dart from all packages.
+/// set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/linux/")
+/// install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+///    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+///    COMPONENT Runtime)
+/// ```
+class CmakeNativeAssetsMigration extends ProjectMigrator {
+  CmakeNativeAssetsMigration(CmakeBasedProject project, this.os, super.logger)
+      : _cmakeFile = project.managedCmakeFile;
+
+  final File _cmakeFile;
+  final String os;
+
+  @override
+  void migrate() {
+    if (!_cmakeFile.existsSync()) {
+      logger.printTrace('CMake project not found, skipping install() NATIVE_ASSETS_DIR migration.');
+      return;
+    }
+
+    final String originalProjectContents = _cmakeFile.readAsStringSync();
+
+    if (originalProjectContents.contains('set(NATIVE_ASSETS_DIR')) {
+      // Command is already present.
+      return;
+    }
+
+    final String copyNativeAssetsCommand = '''
+
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "\${PROJECT_BUILD_DIR}native_assets/$os/")
+install(DIRECTORY "\${NATIVE_ASSETS_DIR}"
+   DESTINATION "\${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+''';
+
+    // Insert the new command after the bundled libraries loop.
+    const String bundleLibrariesCommandEnd = r'''
+endforeach(bundled_library)
+''';
+
+    String newProjectContents = originalProjectContents;
+
+    newProjectContents = originalProjectContents.replaceFirst(
+      bundleLibrariesCommandEnd,
+      '$bundleLibrariesCommandEnd$copyNativeAssetsCommand',
+    );
+
+    if (originalProjectContents != newProjectContents) {
+      logger.printStatus('CMake missing install() NATIVE_ASSETS_DIR command, updating.');
+      _cmakeFile.writeAsStringSync(newProjectContents);
+    }
+  }
+}

packages/flutter_tools/lib/src/native_assets.dart

@@ -19,6 +19,7 @@ import 'cache.dart';
 import 'features.dart';
 import 'globals.dart' as globals;
 import 'ios/native_assets.dart';
+import 'linux/native_assets.dart';
 import 'macos/native_assets.dart';
 import 'macos/native_assets_host.dart';
 import 'resident_runner.dart';
@@ -168,6 +169,9 @@ class NativeAssetsBuildRunnerImpl implements NativeAssetsBuildRunner {
     if (globals.platform.isMacOS || globals.platform.isIOS) {
       return cCompilerConfigMacOS();
     }
+    if (globals.platform.isLinux) {
+      return cCompilerConfigLinux();
+    }
     throwToolExit(
       'Native assets feature not yet implemented for Linux, Windows and Android.',
     );
@@ -333,6 +337,13 @@ Future<Uri?> dryRunNativeAssets({
           fileSystem: fileSystem,
           buildRunner: buildRunner,
         );
+      } else if (const LocalPlatform().isLinux) {
+        nativeAssetsYaml = await dryRunNativeAssetsLinux(
+          projectUri: projectUri,
+          flutterTester: true,
+          fileSystem: fileSystem,
+          buildRunner: buildRunner,
+        );
       } else {
         await ensureNoNativeAssetsOrOsIsSupported(
           projectUri,
@@ -342,6 +353,13 @@ Future<Uri?> dryRunNativeAssets({
         );
         nativeAssetsYaml = null;
       }
+    case build_info.TargetPlatform.linux_arm64:
+    case build_info.TargetPlatform.linux_x64:
+      nativeAssetsYaml = await dryRunNativeAssetsLinux(
+        projectUri: projectUri,
+        fileSystem: fileSystem,
+        buildRunner: buildRunner,
+      );
     case build_info.TargetPlatform.android_arm:
     case build_info.TargetPlatform.android_arm64:
     case build_info.TargetPlatform.android_x64:
@@ -349,8 +367,6 @@ Future<Uri?> dryRunNativeAssets({
     case build_info.TargetPlatform.android:
     case build_info.TargetPlatform.fuchsia_arm64:
     case build_info.TargetPlatform.fuchsia_x64:
-    case build_info.TargetPlatform.linux_arm64:
-    case build_info.TargetPlatform.linux_x64:
     case build_info.TargetPlatform.web_javascript:
     case build_info.TargetPlatform.windows_x64:
       await ensureNoNativeAssetsOrOsIsSupported(
@@ -382,7 +398,12 @@ Future<Uri?> dryRunNativeAssetsMultipeOSes({
     if (targetPlatforms.contains(build_info.TargetPlatform.darwin) ||
         (targetPlatforms.contains(build_info.TargetPlatform.tester) && OS.current == OS.macOS))
       ...await dryRunNativeAssetsMacOSInternal(fileSystem, projectUri, false, buildRunner),
-    if (targetPlatforms.contains(build_info.TargetPlatform.ios)) ...await dryRunNativeAssetsIOSInternal(fileSystem, projectUri, buildRunner)
+    if (targetPlatforms.contains(build_info.TargetPlatform.linux_arm64) ||
+        targetPlatforms.contains(build_info.TargetPlatform.linux_x64) ||
+        (targetPlatforms.contains(build_info.TargetPlatform.tester) && OS.current == OS.linux))
+      ...await dryRunNativeAssetsLinuxInternal(fileSystem, projectUri, false, buildRunner),
+    if (targetPlatforms.contains(build_info.TargetPlatform.ios))
+      ...await dryRunNativeAssetsIOSInternal(fileSystem, projectUri, buildRunner)
   ];
   final Uri nativeAssetsUri = await writeNativeAssetsYaml(nativeAssetPaths, buildUri_, fileSystem);
   return nativeAssetsUri;

packages/flutter_tools/lib/src/test/test_compiler.dart

@@ -16,6 +16,7 @@ import '../bundle.dart';
 import '../compile.dart';
 import '../flutter_plugins.dart';
 import '../globals.dart' as globals;
+import '../linux/native_assets.dart';
 import '../macos/native_assets.dart';
 import '../native_assets.dart';
 import '../project.dart';
@@ -181,7 +182,15 @@ class TestCompiler {
           flutterTester: true,
           fileSystem: globals.fs,
           buildRunner: buildRunner,
-      );
+        );
+      } else if (globals.platform.isLinux) {
+        (nativeAssetsYaml, _) = await buildNativeAssetsLinux(
+          buildMode: BuildMode.debug,
+          projectUri: projectUri,
+          flutterTester: true,
+          fileSystem: globals.fs,
+          buildRunner: buildRunner,
+        );
       } else {
         await ensureNoNativeAssetsOrOsIsSupported(
           projectUri,

packages/flutter_tools/templates/app_shared/linux.tmpl/CMakeLists.txt.tmpl

@@ -127,6 +127,12 @@ foreach(bundled_library ${PLUGIN_BUNDLED_LIBRARIES})
     COMPONENT Runtime)
 endforeach(bundled_library)
 
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/linux/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+
 # Fully re-copy the assets directory on each build to avoid having stale files
 # from a previous install.
 set(FLUTTER_ASSET_DIR_NAME "flutter_assets")

packages/flutter_tools/test/general.shard/migrations/cmake_project_migration_test.dart

@@ -8,6 +8,7 @@ import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/terminal.dart';
 import 'package:flutter_tools/src/cmake_project.dart';
 import 'package:flutter_tools/src/migrations/cmake_custom_command_migration.dart';
+import 'package:flutter_tools/src/migrations/cmake_native_assets_migration.dart';
 import 'package:test/fake.dart';
 
 import '../../src/common.dart';
@@ -155,6 +156,132 @@ add_custom_command(
         expect(testLogger.statusText, contains('add_custom_command() missing VERBATIM or FLUTTER_TARGET_PLATFORM, updating.'));
       });
     });
+
+    group('migrate add install() NATIVE_ASSETS_DIR command', () {
+      late MemoryFileSystem memoryFileSystem;
+      late BufferLogger testLogger;
+      late FakeCmakeProject mockCmakeProject;
+      late File managedCmakeFile;
+
+      setUp(() {
+        memoryFileSystem = MemoryFileSystem.test();
+        managedCmakeFile = memoryFileSystem.file('CMakeLists.txtx');
+
+        testLogger = BufferLogger(
+          terminal: Terminal.test(),
+          outputPreferences: OutputPreferences.test(),
+        );
+
+        mockCmakeProject = FakeCmakeProject(managedCmakeFile);
+      });
+
+      testWithoutContext('skipped if files are missing', () {
+        final CmakeNativeAssetsMigration cmakeProjectMigration = CmakeNativeAssetsMigration(
+          mockCmakeProject,
+          'linux',
+          testLogger,
+        );
+        cmakeProjectMigration.migrate();
+        expect(managedCmakeFile.existsSync(), isFalse);
+
+        expect(testLogger.traceText, contains('CMake project not found, skipping install() NATIVE_ASSETS_DIR migration.'));
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skipped if nothing to migrate', () {
+        const String contents = 'Nothing to migrate';
+        managedCmakeFile.writeAsStringSync(contents);
+        final DateTime projectLastModified = managedCmakeFile.lastModifiedSync();
+
+        final CmakeNativeAssetsMigration cmakeProjectMigration = CmakeNativeAssetsMigration(
+          mockCmakeProject,
+          'linux',
+          testLogger,
+        );
+        cmakeProjectMigration.migrate();
+
+        expect(managedCmakeFile.lastModifiedSync(), projectLastModified);
+        expect(managedCmakeFile.readAsStringSync(), contents);
+
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      testWithoutContext('skipped if already migrated', () {
+        const String contents = r'''
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/linux/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+''';
+        managedCmakeFile.writeAsStringSync(contents);
+        final DateTime projectLastModified = managedCmakeFile.lastModifiedSync();
+
+        final CmakeNativeAssetsMigration cmakeProjectMigration = CmakeNativeAssetsMigration(
+          mockCmakeProject,
+          'linux',
+          testLogger,
+        );
+        cmakeProjectMigration.migrate();
+
+        expect(managedCmakeFile.lastModifiedSync(), projectLastModified);
+        expect(managedCmakeFile.readAsStringSync(), contents);
+
+        expect(testLogger.statusText, isEmpty);
+      });
+
+      // TODO(dacoharkes): Add test for Windows when adding Windows support. https://github.com/flutter/flutter/issues/129757
+      testWithoutContext('is migrated to copy native assets', () {
+        managedCmakeFile.writeAsStringSync(r'''
+foreach(bundled_library ${PLUGIN_BUNDLED_LIBRARIES})
+  install(FILES "${bundled_library}"
+    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endforeach(bundled_library)
+
+# Fully re-copy the assets directory on each build to avoid having stale files
+# from a previous install.
+set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
+install(CODE "
+  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
+  " COMPONENT Runtime)
+install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
+  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
+''');
+
+        final CmakeNativeAssetsMigration cmakeProjectMigration = CmakeNativeAssetsMigration(
+          mockCmakeProject,
+          'linux',
+          testLogger,
+        );
+        cmakeProjectMigration.migrate();
+
+        expect(managedCmakeFile.readAsStringSync(), r'''
+foreach(bundled_library ${PLUGIN_BUNDLED_LIBRARIES})
+  install(FILES "${bundled_library}"
+    DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+    COMPONENT Runtime)
+endforeach(bundled_library)
+
+# Copy the native assets provided by the build.dart from all packages.
+set(NATIVE_ASSETS_DIR "${PROJECT_BUILD_DIR}native_assets/linux/")
+install(DIRECTORY "${NATIVE_ASSETS_DIR}"
+   DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
+   COMPONENT Runtime)
+
+# Fully re-copy the assets directory on each build to avoid having stale files
+# from a previous install.
+set(FLUTTER_ASSET_DIR_NAME "flutter_assets")
+install(CODE "
+  file(REMOVE_RECURSE \"${INSTALL_BUNDLE_DATA_DIR}/${FLUTTER_ASSET_DIR_NAME}\")
+  " COMPONENT Runtime)
+install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
+  DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
+''');
+
+        expect(testLogger.statusText, contains('CMake missing install() NATIVE_ASSETS_DIR command, updating.'));
+      });
+    });
   });
 }
 

packages/flutter_tools/test/integration.shard/native_assets_test.dart

@@ -17,6 +17,7 @@ import 'dart:io';
 
 import 'package:file/file.dart';
 import 'package:file_testing/file_testing.dart';
+import 'package:native_assets_cli/native_assets_cli.dart';
 
 import '../src/common.dart';
 import 'test_utils.dart' show fileSystem, platform;
@@ -56,10 +57,8 @@ const String packageName = 'package_with_native_assets';
 
 const String exampleAppName = '${packageName}_example';
 
-const String dylibName = 'lib$packageName.dylib';
-
 void main() {
-  if (!platform.isMacOS) {
+  if (!platform.isMacOS && !platform.isLinux) {
     // TODO(dacoharkes): Implement other OSes. https://github.com/flutter/flutter/issues/129757
     return;
   }
@@ -148,6 +147,9 @@ void main() {
           if (device == 'macos') {
             expectDylibIsBundledMacOS(exampleDirectory, buildMode);
           }
+          if (device == 'linux') {
+            expectDylibIsBundledLinux(exampleDirectory, buildMode);
+          }
           if (device == hostOs) {
             expectCCompilerIsConfigured(exampleDirectory);
           }
@@ -201,6 +203,8 @@ void main() {
             expectDylibIsBundledMacOS(exampleDirectory, buildMode);
           } else if (buildSubcommand == 'ios') {
             expectDylibIsBundledIos(exampleDirectory, buildMode);
+          } else if (buildSubcommand == 'linux') {
+            expectDylibIsBundledLinux(exampleDirectory, buildMode);
           }
           expectCCompilerIsConfigured(exampleDirectory);
         });
@@ -278,7 +282,7 @@ void expectDylibIsBundledMacOS(Directory appDirectory, String buildMode) {
   expect(appBundle, exists);
   final Directory dylibsFolder = appBundle.childDirectory('Contents/Frameworks');
   expect(dylibsFolder, exists);
-  final File dylib = dylibsFolder.childFile(dylibName);
+  final File dylib = dylibsFolder.childFile(OS.macOS.dylibFileName(packageName));
   expect(dylib, exists);
 }
 
@@ -287,7 +291,21 @@ void expectDylibIsBundledIos(Directory appDirectory, String buildMode) {
   expect(appBundle, exists);
   final Directory dylibsFolder = appBundle.childDirectory('Frameworks');
   expect(dylibsFolder, exists);
-  final File dylib = dylibsFolder.childFile(dylibName);
+  final File dylib = dylibsFolder.childFile(OS.iOS.dylibFileName(packageName));
+  expect(dylib, exists);
+}
+
+/// Checks that dylibs are bundled.
+///
+/// Sample path: build/linux/x64/release/bundle/lib/libmy_package.so
+void expectDylibIsBundledLinux(Directory appDirectory, String buildMode) {
+  // Linux does not support cross compilation, so always only check current architecture.
+  final String architecture = Architecture.current.dartPlatform;
+  final Directory appBundle = appDirectory.childDirectory('build/$hostOs/$architecture/$buildMode/bundle/');
+  expect(appBundle, exists);
+  final Directory dylibsFolder = appBundle.childDirectory('lib/');
+  expect(dylibsFolder, exists);
+  final File dylib = dylibsFolder.childFile(OS.linux.dylibFileName(packageName));
   expect(dylib, exists);
 }
 
@@ -296,7 +314,7 @@ void expectDylibIsBundledIos(Directory appDirectory, String buildMode) {
 void expectDylibIsBundledWithFrameworks(Directory appDirectory, String buildMode, String os) {
   final Directory frameworksFolder = appDirectory.childDirectory('build/$os/framework/${buildMode.upperCaseFirst()}');
   expect(frameworksFolder, exists);
-  final File dylib = frameworksFolder.childFile(dylibName);
+  final File dylib = frameworksFolder.childFile(OS.macOS.dylibFileName(packageName));
   expect(dylib, exists);
 }
 

packages/flutter_tools/test/integration.shard/transition_test_utils.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:flutter_tools/src/base/platform.dart';
 import 'package:meta/meta.dart';
 import 'package:process/process.dart';
 
@@ -177,9 +178,15 @@ Future<ProcessTestResult> runFlutter(
       minutes:
           10), // must be less than test timeout of 15 minutes! See ../../dart_test.yaml.
 }) async {
+  const LocalPlatform platform = LocalPlatform();
   final Stopwatch clock = Stopwatch()..start();
   final Process process = await processManager.start(
-    <String>[flutterBin, ...arguments],
+    <String>[
+      // In a container with no X display, use the virtual framebuffer.
+      if (platform.isLinux && (platform.environment['DISPLAY'] ?? '').isEmpty) '/usr/bin/xvfb-run',
+      flutterBin,
+      ...arguments,
+    ],
     workingDirectory: workingDirectory,
   );
   final List<LogLine> logs = <LogLine>[];