Add timeout to tar command and exit if it doesn't succeed.

packages/fuchsia_ctl/bin/main.dart

@@ -262,7 +262,12 @@ Future<OperationResult> pushPackages(
 
     stdout.writeln('Untaring $repoArchive to ${repo.path}');
     repo.createSync(recursive: true);
-    await tar.untar(repoArchive, repo.path);
+    final OperationResult result = await tar.untar(repoArchive, repo.path);
+    if (!result.success) {
+      stdout.writeln(
+          'Error untarring $repoArchive \nstdout: ${result.info} \nstderr: ${result.error}');
+      exit(-1);
+    }
 
     final String repositoryBase = path.join(repo.path, 'amber-files');
     stdout.writeln('Serving $repositoryBase to $targetIp');

packages/fuchsia_ctl/lib/src/tar.dart

@@ -17,7 +17,11 @@ abstract class Tar {
   const Tar();
 
   /// Untars a tar file.
-  Future<OperationResult> untar(String src, String destination);
+  Future<OperationResult> untar(
+    String src,
+    String destination, {
+    Duration timeoutMs,
+  });
 }
 
 /// The archive package is very slow and memory intensive. Use
@@ -35,16 +39,21 @@ class SystemTar implements Tar {
   /// program.
   final ProcessManager processManager;
 
+  /// The default timeout for untar operations as [Duration] in milliseconds.
+  static const Duration defaultTarTimeoutMs =
+      Duration(milliseconds: 5 * 60 * 1000);
+
   @override
   Future<OperationResult> untar(
     String src,
-    String destination,
-  ) async {
+    String destination, {
+    Duration timeoutMs = defaultTarTimeoutMs,
+  }) async {
     final ProcessResult result = await processManager.run(<String>[
       'tar',
-      '-xvf', src, //
+      '-xf', src, //
       '-C', destination,
-    ]);
+    ]).timeout(timeoutMs);
 
     return OperationResult.fromProcessResult(result);
   }

packages/fuchsia_ctl/test/image_paver_test.dart

@@ -158,7 +158,8 @@ class FakeTar implements Tar {
   final MemoryFileSystem fs;
 
   @override
-  Future<OperationResult> untar(String src, String destination) async {
+  Future<OperationResult> untar(String src, String destination,
+      {Duration timeoutMs}) async {
     if (passes) {
       final Directory dir = fs.directory(destination)
         ..createSync(recursive: true);

packages/fuchsia_ctl/test/tar_test.dart

@@ -0,0 +1,35 @@
+// Copyright 2020 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 'dart:async';
+import 'dart:io';
+
+import 'package:process/process.dart';
+import 'package:test/test.dart';
+import 'package:fuchsia_ctl/src/tar.dart';
+import 'package:mockito/mockito.dart';
+
+void main() {
+  group('Tar', () {
+    test('Untar file times out', () async {
+      final MockProcessManager processManager = MockProcessManager();
+
+      when(processManager.run(any)).thenAnswer((_) async {
+        await Future<void>.delayed(const Duration(milliseconds: 3));
+        return ProcessResult(0, 0, 'Good job', '');
+      });
+
+      final Tar tar = SystemTar(processManager: processManager);
+      expect(
+          tar.untar(
+            'source.tar',
+            '/destination',
+            timeoutMs: const Duration(milliseconds: 1),
+          ),
+          throwsA(const TypeMatcher<TimeoutException>()));
+    });
+  });
+}
+
+class MockProcessManager extends Mock implements ProcessManager {}