Fix logic for finding libwebcrypto.so in tests (#35)

* Fix logic for finding libwebcrypto.so in tests

* Update lib/src/boringssl/lookup/utils.dart

Co-authored-by: Sigurd Meldgaard <[email protected]>

* Better explanation

Co-authored-by: Sigurd Meldgaard <[email protected]>

Author: jonasfj

lib/src/boringssl/lookup/lookup.dart

@@ -12,16 +12,53 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+// ignore_for_file: non_constant_identifier_names
+
 import 'dart:ffi';
 
 import '../../third_party/boringssl/generated_bindings.dart';
 import '../bindings/generated_bindings.dart';
 
-import 'lookup_symbol_dart.dart'
-    if (dart.library.ui) 'lookup_symbol_flutter.dart';
+import 'dart:io' show Platform;
+
+import 'symbols.generated.dart';
+import 'utils.dart';
 
 export 'symbols.generated.dart' show Sym;
 
+/// Dynamically load `webcrypto_lookup_symbol` function.
+final Pointer<T> Function<T extends NativeType>(String symbolName) lookup = () {
+  try {
+    final library = Platform.isAndroid || Platform.isLinux
+        ? DynamicLibrary.open('libwebcrypto.so')
+        : DynamicLibrary.executable();
+
+    // Try to lookup the 'webcrypto_lookup_symbol' symbol.
+    final webcryptoDartDL = WebCryptoDartDL(library);
+    final webcrypto_lookup_symbol = webcryptoDartDL.webcrypto_lookup_symbol;
+
+    // Return a function from Sym to lookup using `webcrypto_lookup_symbol`
+    Pointer<T> lookup<T extends NativeType>(String s) =>
+        webcrypto_lookup_symbol(symFromString(s).index).cast<T>();
+
+    // Initialize the dynamic linking with Dart.
+    initialize_dart_dl(lookup);
+
+    return lookup;
+  } on ArgumentError {
+    final lookup = lookupLibraryInDotDartTool();
+    if (lookup != null) {
+      return lookup;
+    }
+
+    throw UnsupportedError(
+      'package:webcrypto cannot be used from scripts or `flutter test` '
+      'unless `flutter pub run webcrypto:setup` has been run for the current '
+      'root project.',
+    );
+  }
+}();
+
 final Pointer<T> Function<T extends NativeType>(String symbolName)
     _cachedLookup = lookup;
 

lib/src/boringssl/lookup/lookup_symbol_dart.dart

@@ -60,7 +60,7 @@ Pointer<T> Function<T extends NativeType>(String symbolName)?
     final webcrypto_lookup_symbol = webcryptoDartDL.webcrypto_lookup_symbol;
 
     // Return a function from Sym to lookup using `webcrypto_lookup_symbol`
-    final lookup = <T extends NativeType>(String s) =>
+    Pointer<T> lookup<T extends NativeType>(String s) =>
         webcrypto_lookup_symbol(symFromString(s).index).cast<T>();
 
     // Initialize library
@@ -92,23 +92,12 @@ void initialize_dart_dl(
 
 /// Find the `.dart_tool/` folder, returns `null` if unable to find it.
 Uri? _findDotDartTool() {
-  // HACK: Because 'dart:isolate' is unavailable in Flutter we have no means
-  //       by which we can find the location of the package_config.json file.
-  //       Which we need, because the binary library created by:
+  // HACK: We have no good mechanism for finding the library created by:
   //         flutter pub run webcrypto:setup
-  //       is located relative to this path. As a workaround we use
-  //       `Platform.script` and traverse level-up until we find a
-  //       `.dart_tool/package_config.json` file.
+  //       So we search relative to the script path and CWD.
 
   // Find script directory
-  Uri root;
-  if (Platform.script.isScheme('data')) {
-    // If `Platform.script` is a data: [Uri] then we are being called from
-    // `package:test`, luckily this means that CWD is project root.
-    root = Directory.current.uri;
-  } else {
-    root = Platform.script.resolve('./');
-  }
+  Uri root = Platform.script.resolve('./');
 
   // Traverse up until we see a `.dart_tool/package_config.json` file.
   do {
@@ -117,5 +106,18 @@ Uri? _findDotDartTool() {
       return root.resolve('.dart_tool/');
     }
   } while (root != (root = root.resolve('..')));
+
+  // If traversing from script directory didn't work, we can look starting from
+  // CWD, this typically happens if running as test.
+  root = Directory.current.uri;
+
+  // Traverse up until we see a `.dart_tool/package_config.json` file.
+  do {
+    if (File.fromUri(root.resolve('.dart_tool/package_config.json'))
+        .existsSync()) {
+      return root.resolve('.dart_tool/');
+    }
+  } while (root != (root = root.resolve('..')));
+
   return null;
 }