Merge pull request #126 from phlip9/fix_ffi_bugs

ffi: fix crashes from use-after-free. fix memory leaks. correctness cleanups.

ffigen.yaml

@@ -10,9 +10,6 @@ headers:
     - "src/native_zxing.h"
   include-directives:
     - "src/native_zxing.h"
-functions:
-  exclude:
-    - "resultToCodeResult"
 preamble: |
   // ignore_for_file: always_specify_types
   // ignore_for_file: camel_case_types

lib/generated_bindings.dart

@@ -28,23 +28,22 @@ class GeneratedBindings {
       : _lookup = lookup;
 
   /// @brief Enables or disables the logging of the library.
-  /// @param enable Whether to enable or disable the logging.
   ///
-  /// @param enabled
+  /// @param enabled Whether to enable or disable the logging.
   void setLogEnabled(
-    int enable,
+    bool enabled,
   ) {
     return _setLogEnabled(
-      enable,
+      enabled,
     );
   }
 
   late final _setLogEnabledPtr =
-      _lookup<ffi.NativeFunction<ffi.Void Function(ffi.Int)>>('setLogEnabled');
+      _lookup<ffi.NativeFunction<ffi.Void Function(ffi.Bool)>>('setLogEnabled');
   late final _setLogEnabled =
-      _setLogEnabledPtr.asFunction<void Function(int)>();
+      _setLogEnabledPtr.asFunction<void Function(bool)>();
 
-  /// Returns the version of the zxing-cpp library.
+  /// Returns the version of the zxing-cpp library. Pointer has a static lifetime and must not be freed.
   ///
   /// @return The version of the zxing-cpp library.
   ffi.Pointer<ffi.Char> version() {
@@ -57,7 +56,7 @@ class GeneratedBindings {
       _versionPtr.asFunction<ffi.Pointer<ffi.Char> Function()>();
 
   /// @brief Read barcode from image bytes.
-  /// @param bytes Image bytes.
+  /// @param bytes Image bytes. Owned pointer. Will be freed by native code.
   /// @param imageFormat Image format.
   /// @param format Specify a set of BarcodeFormats that should be searched for.
   /// @param width Image width in pixels.
@@ -68,16 +67,16 @@ class GeneratedBindings {
   /// @param tryRotate Also try detecting code in 90, 180 and 270 degree rotated images.
   /// @return The barcode result.
   CodeResult readBarcode(
-    ffi.Pointer<ffi.Char> bytes,
+    ffi.Pointer<ffi.Uint8> bytes,
     int imageFormat,
     int format,
     int width,
     int height,
     int cropWidth,
     int cropHeight,
-    int tryHarder,
-    int tryRotate,
-    int tryInvert,
+    bool tryHarder,
+    bool tryRotate,
+    bool tryInvert,
   ) {
     return _readBarcode(
       bytes,
@@ -96,22 +95,22 @@ class GeneratedBindings {
   late final _readBarcodePtr = _lookup<
       ffi.NativeFunction<
           CodeResult Function(
-              ffi.Pointer<ffi.Char>,
+              ffi.Pointer<ffi.Uint8>,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
-              ffi.Int,
-              ffi.Int,
-              ffi.Int)>>('readBarcode');
+              ffi.Bool,
+              ffi.Bool,
+              ffi.Bool)>>('readBarcode');
   late final _readBarcode = _readBarcodePtr.asFunction<
-      CodeResult Function(ffi.Pointer<ffi.Char>, int, int, int, int, int, int,
-          int, int, int)>();
+      CodeResult Function(ffi.Pointer<ffi.Uint8>, int, int, int, int, int, int,
+          bool, bool, bool)>();
 
   /// @brief Read barcodes from image bytes.
-  /// @param bytes Image bytes.
+  /// @param bytes Image bytes. Owned pointer. Will be freed by native code.
   /// @param imageFormat Image format.
   /// @param format Specify a set of BarcodeFormats that should be searched for.
   /// @param width Image width in pixels.
@@ -122,16 +121,16 @@ class GeneratedBindings {
   /// @param tryRotate Also try detecting code in 90, 180 and 270 degree rotated images.
   /// @return The barcode results.
   CodeResults readBarcodes(
-    ffi.Pointer<ffi.Char> bytes,
+    ffi.Pointer<ffi.Uint8> bytes,
     int imageFormat,
     int format,
     int width,
     int height,
     int cropWidth,
     int cropHeight,
-    int tryHarder,
-    int tryRotate,
-    int tryInvert,
+    bool tryHarder,
+    bool tryRotate,
+    bool tryInvert,
   ) {
     return _readBarcodes(
       bytes,
@@ -150,28 +149,28 @@ class GeneratedBindings {
   late final _readBarcodesPtr = _lookup<
       ffi.NativeFunction<
           CodeResults Function(
-              ffi.Pointer<ffi.Char>,
-              ffi.Int,
-              ffi.Int,
+              ffi.Pointer<ffi.Uint8>,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
               ffi.Int,
-              ffi.Int)>>('readBarcodes');
+              ffi.Bool,
+              ffi.Bool,
+              ffi.Bool)>>('readBarcodes');
   late final _readBarcodes = _readBarcodesPtr.asFunction<
-      CodeResults Function(ffi.Pointer<ffi.Char>, int, int, int, int, int, int,
-          int, int, int)>();
+      CodeResults Function(ffi.Pointer<ffi.Uint8>, int, int, int, int, int, int,
+          bool, bool, bool)>();
 
   /// @brief Encode a string into a barcode
-  /// @param contents The string to encode
+  /// @param contents The string to encode. Owned pointer. Will be freed by native code.
   /// @param width The width of the barcode in pixels.
   /// @param height The height of the barcode in pixels.
   /// @param format The format of the barcode
   /// @param margin The margin of the barcode
   /// @param eccLevel The error correction level of the barcode. Used for Aztec, PDF417, and QRCode only, [0-8].
-  /// @return The barcode data
+  /// @return The barcode data.
   EncodeResult encodeBarcode(
     ffi.Pointer<ffi.Char> contents,
     int width,
@@ -243,18 +242,18 @@ final class Pos extends ffi.Struct {
 
 /// @brief The CodeResult class encapsulates the result of decoding a barcode within an image.
 final class CodeResult extends ffi.Struct {
-  /// < The decoded text
+  /// < The decoded text. Owned pointer. Must be freed by Dart code if not null.
   external ffi.Pointer<ffi.Char> text;
 
   /// < Whether the barcode was successfully decoded
-  @ffi.Int()
-  external int isValid;
+  @ffi.Bool()
+  external bool isValid;
 
-  /// < The error message
+  /// < The error message. Owned pointer. Must be freed by Dart code if not null.
   external ffi.Pointer<ffi.Char> error;
 
-  /// < The bytes is the raw / standard content without any modifications like character set conversions
-  external ffi.Pointer<ffi.UnsignedChar> bytes;
+  /// < The bytes is the raw content without any character set conversions. Owned pointer. Must be freed by Dart code if not null.
+  external ffi.Pointer<ffi.Uint8> bytes;
 
   /// < The length of the bytes
   @ffi.Int()
@@ -265,15 +264,15 @@ final class CodeResult extends ffi.Struct {
   external int format;
 
   /// < The position of the barcode within the image
-  external ffi.Pointer<Pos> pos;
+  external Pos pos;
 
   /// < Whether the barcode was inverted
-  @ffi.Int()
-  external int isInverted;
+  @ffi.Bool()
+  external bool isInverted;
 
   /// < Whether the barcode was mirrored
-  @ffi.Int()
-  external int isMirrored;
+  @ffi.Bool()
+  external bool isMirrored;
 
   /// < The duration of the decoding in milliseconds
   @ffi.Int()
@@ -286,7 +285,7 @@ final class CodeResults extends ffi.Struct {
   @ffi.Int()
   external int count;
 
-  /// < The results of the barcode decoding
+  /// < The results of the barcode decoding. Owned pointer. Must be freed by Dart code.
   external ffi.Pointer<CodeResult> results;
 
   /// < The duration of the decoding in milliseconds
@@ -297,23 +296,23 @@ final class CodeResults extends ffi.Struct {
 /// @brief EncodeResult encapsulates the result of encoding a barcode.
 final class EncodeResult extends ffi.Struct {
   /// < Whether the barcode was successfully encoded
-  @ffi.Int()
-  external int isValid;
+  @ffi.Bool()
+  external bool isValid;
 
-  /// < The encoded text
+  /// < The encoded text. Owned pointer. Must be freed by Dart code if not null.
   external ffi.Pointer<ffi.Char> text;
 
   /// < The format of the barcode
   @ffi.Int()
   external int format;
 
-  /// < The encoded data
-  external ffi.Pointer<ffi.SignedChar> data;
+  /// < The encoded data. Owned pointer. Must be freed by Dart code if not null.
+  external ffi.Pointer<ffi.Uint8> data;
 
   /// < The length of the encoded data
   @ffi.Int()
   external int length;
 
-  /// < The error message
+  /// < The error message. Owned pointer. Must be freed by Dart code if not null.
   external ffi.Pointer<ffi.Char> error;
 }

lib/src/logic/barcode_reader.dart

@@ -67,16 +67,16 @@ Code _readBarcode(
 ) {
   return bindings
       .readBarcode(
-        bytes.allocatePointer(),
+        bytes.copyToNativePointer(),
         params?.imageFormat ?? zx.ImageFormat.lum,
         params?.format ?? Format.any,
         width,
         height,
         params?.cropWidth ?? 0,
         params?.cropHeight ?? 0,
-        params?.tryHarder ?? false ? 1 : 0,
-        params?.tryRotate ?? true ? 1 : 0,
-        params?.tryInverted ?? false ? 1 : 0,
+        params?.tryHarder ?? false,
+        params?.tryRotate ?? true,
+        params?.tryInverted ?? false,
       )
       .toCode();
 }

lib/src/logic/barcodes_reader.dart

@@ -66,20 +66,27 @@ Codes _readBarcodes(
   DecodeParams? params,
 ) {
   final CodeResults result = bindings.readBarcodes(
-    bytes.allocatePointer(),
+    bytes.copyToNativePointer(),
     params?.imageFormat ?? zx.ImageFormat.lum,
     params?.format ?? Format.any,
     width,
     height,
     params?.cropWidth ?? 0,
     params?.cropHeight ?? 0,
-    params?.tryHarder ?? false ? 1 : 0,
-    params?.tryRotate ?? true ? 1 : 0,
-    params?.tryInverted ?? false ? 1 : 0,
+    params?.tryHarder ?? false,
+    params?.tryRotate ?? true,
+    params?.tryInverted ?? false,
   );
-  final List<Code> results = <Code>[];
+
+  final List<Code> codes = <Code>[];
+
+  if (result.count == 0 || result.results == nullptr) {
+    return Codes(codes: codes, duration: result.duration);
+  }
+
   for (int i = 0; i < result.count; i++) {
-    results.add(result.results.elementAt(i).ref.toCode());
+    codes.add(result.results.elementAt(i).ref.toCode());
   }
-  return Codes(codes: results, duration: result.duration);
+  malloc.free(result.results);
+  return Codes(codes: codes, duration: result.duration);
 }

lib/src/logic/zxing.dart

@@ -27,18 +27,17 @@ part 'camera_stream.dart';
 String zxingVersion() => bindings.version().cast<Utf8>().toDartString();
 
 /// Enables or disables the logging of the library
-void setZxingLogEnabled(bool enabled) =>
-    bindings.setLogEnabled(enabled ? 1 : 0);
+void setZxingLogEnabled(bool enabled) => bindings.setLogEnabled(enabled);
 
 /// Returns a readable barcode format name
 String zxingBarcodeFormatName(int format) => barcodeNames[format] ?? 'Unknown';
 
-extension Uint8ListBlobConversion on Uint8List {
-  /// Allocates a pointer filled with the Uint8List data.
-  Pointer<Char> allocatePointer() {
-    final Pointer<Int8> blob = calloc<Int8>(length);
-    final Int8List blobBytes = blob.asTypedList(length);
-    blobBytes.setAll(0, this);
-    return blob.cast<Char>();
+extension Uint8ListExt on Uint8List {
+  /// Copy the [Uint8List] into a freshly allocated [Pointer<Uint8>].
+  Pointer<Uint8> copyToNativePointer() {
+    final Pointer<Uint8> ptr = malloc<Uint8>(length);
+    final Uint8List view = ptr.asTypedList(length);
+    view.setAll(0, this);
+    return ptr;
   }
 }