Script to verify exported symbols on release binaries (flutter#6363)

.gitignore

@@ -19,3 +19,4 @@ Session.vim
 tags
 Thumbs.db
 .idea
+pubspec.lock

testing/symbols/pubspec.yaml

@@ -0,0 +1,3 @@
+name: verify_exported
+dependencies:
+  path: 1.6.2

testing/symbols/verify_exported.dart

@@ -0,0 +1,99 @@
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:path/path.dart' as p;
+
+// This script verifies that the release binaries only export the expected
+// symbols.
+//
+// Android binaries (libflutter.so) should only export one symbol "JNI_OnLoad"
+// of type "T".
+//
+// iOS binaries (Flutter.framework/Flutter) should only export Objective-C
+// Symbols from the Flutter namespace. These are either of type
+// "(__DATA,__common)" or "(__DATA,__objc_data)".
+
+/// Takes the path to the out directory as argument.
+void main(List<String> arguments) {
+  assert(arguments.length == 1);
+  final String outPath = arguments.first;
+  assert(new Directory(outPath).existsSync());
+
+  final Iterable<String> releaseBuilds = new Directory(outPath).listSync()
+      .where((FileSystemEntity entity) => entity is Directory)
+      .map((FileSystemEntity dir) => p.basename(dir.path))
+      .where((String s) => s.contains('_release'));
+
+  final Iterable<String> iosReleaseBuilds = releaseBuilds
+      .where((String s) => s.startsWith('ios_'));
+  final Iterable<String> androidReleaseBuilds = releaseBuilds
+      .where((String s) => s.startsWith('android_'));
+
+  int failures = 0;
+  failures += _checkIos(outPath, iosReleaseBuilds);
+  failures += _checkAndroid(outPath, androidReleaseBuilds);
+
+  exit(failures);
+}
+
+int _checkIos(String outPath, Iterable<String> builds) {
+  int failures = 0;
+  for (String build in builds) {
+    final String libFlutter = p.join(outPath, build, 'Flutter.framework', 'Flutter');
+    final String stdout = Process.runSync('nm', <String>['-gUm', libFlutter]).stdout;
+    final Iterable<NmEntry> unexpectedEntries = NmEntry.parse(stdout).where((NmEntry entry) {
+      return !((entry.type == '(__DATA,__common)' && entry.name.startsWith('_Flutter'))
+          || (entry.type == '(__DATA,__objc_data)'
+              && (entry.name.startsWith('_OBJC_METACLASS_\$_Flutter') || entry.name.startsWith('_OBJC_CLASS_\$_Flutter'))));
+    });
+    if (unexpectedEntries.isNotEmpty) {
+      print('ERROR: $libFlutter exports unexpected symbols:');
+      print(unexpectedEntries.fold<String>('', (String previous, NmEntry entry) {
+        return '${previous == '' ? '' : '$previous\n'}     ${entry.type} ${entry.name}';
+      }));
+      failures++;
+    } else {
+      print('OK: $libFlutter');
+    }
+  }
+  return failures;
+}
+
+int _checkAndroid(String outPath, Iterable<String> builds) {
+  int failures = 0;
+  for (String build in builds) {
+    final String libFlutter = p.join(outPath, build, 'libflutter.so');
+    final String stdout = Process.runSync('nm', <String>['-gU', libFlutter]).stdout;
+    final Iterable<NmEntry> entries = NmEntry.parse(stdout);
+    if (entries.isEmpty) {
+      print('ERROR: $libFlutter exports no symbol');
+      print(' Expected exactly one symbol "JNI_OnLoad" of type "T", but got none.');
+      failures++;
+    } else if (entries.length > 1 || entries.first.type != 'T' || entries.first.name != 'JNI_OnLoad') {
+      print('ERROR: $libFlutter exports unexpected symbols.');
+      print('  Expected exactly one symbol "JNI_OnLoad" of type "T", but got instead:');
+      print(entries.fold<String>('', (String previous, NmEntry entry) {
+        return '${previous == '' ? '' : '$previous\n'}     ${entry.type} ${entry.name}';
+      }));
+      failures++;
+    } else {
+      print('OK: $libFlutter');
+    }
+  }
+  return failures;
+}
+
+class NmEntry {
+  NmEntry._(this.address, this.type, this.name);
+
+  final String address;
+  final String type;
+  final String name;
+
+  static Iterable<NmEntry> parse(String stdout) {
+    return LineSplitter.split(stdout).map((String line) {
+      final List<String> parts = line.split(' ');
+      return new NmEntry._(parts[0], parts[1], parts.last);
+    });
+  }
+}