safer svg parsing

android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/MediaFetchBytesHandler.kt

@@ -68,6 +68,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
         val uri = call.argument<String>("uri")?.let { Uri.parse(it) }
         val mimeType = call.argument<String>("mimeType")
         val pageId = call.argument<Int>("pageId")
+        val sizeBytes = call.argument<Number>("sizeBytes")?.toLong()
         val sampleSize = call.argument<Int>("sampleSize")
         val x = call.argument<Int>("regionX")
         val y = call.argument<Int>("regionY")
@@ -85,6 +86,7 @@ class MediaFetchBytesHandler(private val context: Context) : MethodCallHandler {
         when (mimeType) {
             MimeTypes.SVG -> SvgRegionFetcher(context).fetch(
                 uri = uri,
+                sizeBytes = sizeBytes,
                 regionRect = regionRect,
                 imageWidth = imageWidth,
                 imageHeight = imageHeight,

android/app/src/main/kotlin/deckers/thibault/aves/channel/calls/fetchers/SvgRegionFetcher.kt

@@ -23,11 +23,21 @@ class SvgRegionFetcher internal constructor(
 
     suspend fun fetch(
         uri: Uri,
+        sizeBytes: Long?,
         regionRect: Rect,
         imageWidth: Int,
         imageHeight: Int,
         result: MethodChannel.Result,
     ) {
+        if (sizeBytes != null && sizeBytes > FILE_SIZE_DANGER_THRESHOLD) {
+            val availableHeapSize = Runtime.getRuntime().let { it.maxMemory() - (it.totalMemory() - it.freeMemory()) }
+            if (sizeBytes > availableHeapSize) {
+                // opening an SVG that large would yield an OOM during parsing from `com.caverock.androidsvg.SVGParser`
+                result.error("fetch-read-large", "SVG too large at $sizeBytes bytes, with only $availableHeapSize free bytes, for uri=$uri regionRect=$regionRect", null)
+                return
+            }
+        }
+
         var currentSvgRef = lastSvgRef
         if (currentSvgRef != null && currentSvgRef.uri != uri) {
             currentSvgRef = null
@@ -103,4 +113,9 @@ class SvgRegionFetcher internal constructor(
         val uri: Uri,
         val svg: SVG,
     )
+
+    companion object {
+        // arbitrary size to detect files that may yield an OOM
+        private const val FILE_SIZE_DANGER_THRESHOLD = 10 * (1 shl 20) // MB
+    }
 }

android/app/src/main/kotlin/deckers/thibault/aves/metadata/Metadata.kt

@@ -117,16 +117,16 @@ object Metadata {
         return date.time + parseSubSecond(subSecond)
     }
 
-    // opening large PSD/TIFF files yields an OOM (both with `metadata-extractor` v2.15.0 and `ExifInterface` v1.3.1),
+    // Opening large PSD/TIFF files yields an OOM (both with `metadata-extractor` v2.15.0 and `ExifInterface` v1.3.1),
     // so we define an arbitrary threshold to avoid a crash on launch.
     // It is not clear whether it is because of the file itself or its metadata.
-    private const val fileSizeBytesMax = 100 * (1 shl 20) // MB
+    private const val FILE_SIZE_MAX = 100 * (1 shl 20) // MB
 
-    fun isDangerouslyLarge(sizeBytes: Long?) = sizeBytes == null || sizeBytes > fileSizeBytesMax
+    fun isDangerouslyLarge(sizeBytes: Long?) = sizeBytes == null || sizeBytes > FILE_SIZE_MAX
 
     // we try and read metadata from large files by copying an arbitrary amount from its beginning
     // to a temporary file, and reusing that preview file for all metadata reading purposes
-    private const val previewSize: Long = 5 * (1 shl 20) // MB
+    private const val PREVIEW_SIZE: Long = 5 * (1 shl 20) // MB
 
     private val previewFiles = HashMap<Uri, File>()
 
@@ -159,7 +159,7 @@ object Metadata {
     fun createPreviewFile(context: Context, uri: Uri): File {
         return File.createTempFile("aves", null, context.cacheDir).apply {
             deleteOnExit()
-            transferFrom(StorageUtils.openInputStream(context, uri), previewSize)
+            transferFrom(StorageUtils.openInputStream(context, uri), PREVIEW_SIZE)
         }
     }
 

android/app/src/main/kotlin/deckers/thibault/aves/utils/BitmapUtils.kt

@@ -45,9 +45,9 @@ object BitmapUtils {
 
             val bufferSize = stream.size()
             if (bufferSize > BUFFER_SIZE_DANGER_THRESHOLD) {
-                val availHeapSize = Runtime.getRuntime().let { it.maxMemory() - (it.totalMemory() - it.freeMemory()) }
-                if (bufferSize > availHeapSize) {
-                    throw Exception("compressed bitmap to $bufferSize bytes, which cannot be allocated to a new byte array, with only $availHeapSize free bytes")
+                val availableHeapSize = Runtime.getRuntime().let { it.maxMemory() - (it.totalMemory() - it.freeMemory()) }
+                if (bufferSize > availableHeapSize) {
+                    throw Exception("compressed bitmap to $bufferSize bytes, which cannot be allocated to a new byte array, with only $availableHeapSize free bytes")
                 }
             }
 

lib/image_providers/region_provider.dart

@@ -42,6 +42,7 @@ class RegionProvider extends ImageProvider<RegionProviderKey> {
         key.region,
         key.imageSize,
         pageId: pageId,
+        sizeBytes: key.sizeBytes,
         taskKey: key,
       );
       if (bytes.isEmpty) {
@@ -70,7 +71,7 @@ class RegionProviderKey extends Equatable {
   // do not store the entry as it is, because the key should be constant
   // but the entry attributes may change over time
   final String uri, mimeType;
-  final int? pageId;
+  final int? pageId, sizeBytes;
   final int rotationDegrees, sampleSize;
   final bool isFlipped;
   final Rectangle<int> region;
@@ -83,13 +84,11 @@ class RegionProviderKey extends Equatable {
     required this.uri,
     required this.mimeType,
     required this.pageId,
+    required this.sizeBytes,
     required this.rotationDegrees,
     required this.isFlipped,
     required this.sampleSize,
     required this.region,
     required this.imageSize,
   });
-
-  @override
-  String toString() => '$runtimeType#${shortHash(this)}{uri=$uri, mimeType=$mimeType, pageId=$pageId, rotationDegrees=$rotationDegrees, isFlipped=$isFlipped, sampleSize=$sampleSize, region=$region, imageSize=$imageSize}';
 }

lib/image_providers/uri_image_provider.dart

@@ -52,8 +52,8 @@ class UriImage extends ImageProvider<UriImage> with EquatableMixin {
       final bytes = await mediaFetchService.getImage(
         uri,
         mimeType,
-        rotationDegrees,
-        isFlipped,
+        rotationDegrees: rotationDegrees,
+        isFlipped: isFlipped,
         pageId: pageId,
         sizeBytes: sizeBytes,
         onBytesReceived: (cumulative, total) {
@@ -76,7 +76,4 @@ class UriImage extends ImageProvider<UriImage> with EquatableMixin {
       unawaited(chunkEvents.close());
     }
   }
-
-  @override
-  String toString() => '$runtimeType#${shortHash(this)}{uri=$uri, mimeType=$mimeType, rotationDegrees=$rotationDegrees, isFlipped=$isFlipped, pageId=$pageId, scale=$scale}';
 }

lib/model/entry_images.dart

@@ -34,6 +34,7 @@ extension ExtraAvesEntryImages on AvesEntry {
       uri: uri,
       mimeType: mimeType,
       pageId: pageId,
+      sizeBytes: sizeBytes,
       rotationDegrees: rotationDegrees,
       isFlipped: isFlipped,
       sampleSize: sampleSize,

lib/services/media/media_fetch_service.dart

@@ -17,17 +17,17 @@ abstract class MediaFetchService {
   Future<Uint8List> getSvg(
     String uri,
     String mimeType, {
-    int? expectedContentLength,
+    required int? sizeBytes,
     BytesReceivedCallback? onBytesReceived,
   });
 
   Future<Uint8List> getImage(
     String uri,
-    String mimeType,
-    int? rotationDegrees,
-    bool isFlipped, {
-    int? pageId,
-    int? sizeBytes,
+    String mimeType, {
+    required int? rotationDegrees,
+    required bool isFlipped,
+    required int? pageId,
+    required int? sizeBytes,
     BytesReceivedCallback? onBytesReceived,
   });
 
@@ -40,7 +40,8 @@ abstract class MediaFetchService {
     int sampleSize,
     Rectangle<int> regionRect,
     Size imageSize, {
-    int? pageId,
+    required int? pageId,
+    required int? sizeBytes,
     Object? taskKey,
     int? priority,
   });
@@ -93,26 +94,27 @@ class PlatformMediaFetchService implements MediaFetchService {
   Future<Uint8List> getSvg(
     String uri,
     String mimeType, {
-    int? expectedContentLength,
+    required int? sizeBytes,
     BytesReceivedCallback? onBytesReceived,
   }) =>
       getImage(
         uri,
         mimeType,
-        0,
-        false,
-        sizeBytes: expectedContentLength,
+        rotationDegrees: 0,
+        isFlipped: false,
+        pageId: null,
+        sizeBytes: sizeBytes,
         onBytesReceived: onBytesReceived,
       );
 
   @override
   Future<Uint8List> getImage(
     String uri,
-    String mimeType,
-    int? rotationDegrees,
-    bool isFlipped, {
-    int? pageId,
-    int? sizeBytes,
+    String mimeType, {
+    required int? rotationDegrees,
+    required bool isFlipped,
+    required int? pageId,
+    required int? sizeBytes,
     BytesReceivedCallback? onBytesReceived,
   }) async {
     try {
@@ -166,7 +168,8 @@ class PlatformMediaFetchService implements MediaFetchService {
     int sampleSize,
     Rectangle<int> regionRect,
     Size imageSize, {
-    int? pageId,
+    required int? pageId,
+    required int? sizeBytes,
     Object? taskKey,
     int? priority,
   }) {
@@ -176,6 +179,7 @@ class PlatformMediaFetchService implements MediaFetchService {
           final result = await _platformBytes.invokeMethod('getRegion', <String, dynamic>{
             'uri': uri,
             'mimeType': mimeType,
+            'sizeBytes': sizeBytes,
             'pageId': pageId,
             'sampleSize': sampleSize,
             'regionX': regionRect.left,

lib/services/metadata/svg_metadata_service.dart

@@ -17,7 +17,11 @@ class SvgMetadataService {
 
   static Future<Size?> getSize(AvesEntry entry) async {
     try {
-      final data = await mediaFetchService.getSvg(entry.uri, entry.mimeType);
+      final data = await mediaFetchService.getSvg(
+        entry.uri,
+        entry.mimeType,
+        sizeBytes: entry.sizeBytes,
+      );
 
       final document = XmlDocument.parse(utf8.decode(data));
       final root = document.rootElement;
@@ -63,7 +67,11 @@ class SvgMetadataService {
     }
 
     try {
-      final data = await mediaFetchService.getSvg(entry.uri, entry.mimeType);
+      final data = await mediaFetchService.getSvg(
+        entry.uri,
+        entry.mimeType,
+        sizeBytes: entry.sizeBytes,
+      );
 
       final document = XmlDocument.parse(utf8.decode(data));
       final root = document.rootElement;

lib/widgets/viewer/action/entry_action_delegate.dart

@@ -335,7 +335,14 @@ class EntryActionDelegate with FeedbackMixin, PermissionAwareMixin, SizeAwareMix
       MaterialPageRoute(
         settings: const RouteSettings(name: SourceViewerPage.routeName),
         builder: (context) => SourceViewerPage(
-          loader: () => mediaFetchService.getSvg(entry.uri, entry.mimeType).then(utf8.decode),
+          loader: () async {
+            final data = await mediaFetchService.getSvg(
+              entry.uri,
+              entry.mimeType,
+              sizeBytes: entry.sizeBytes,
+            );
+            return utf8.decode(data);
+          },
         ),
       ),
     );

lib/widgets/viewer/action/printer.dart

@@ -74,9 +74,13 @@ class EntryPrinter with FeedbackMixin {
 
   Future<pdf.Widget?> _buildPageImage(AvesEntry entry) async {
     if (entry.isSvg) {
-      final bytes = await mediaFetchService.getSvg(entry.uri, entry.mimeType);
-      if (bytes.isNotEmpty) {
-        return pdf.SvgImage(svg: utf8.decode(bytes));
+      final data = await mediaFetchService.getSvg(
+        entry.uri,
+        entry.mimeType,
+        sizeBytes: entry.sizeBytes,
+      );
+      if (data.isNotEmpty) {
+        return pdf.SvgImage(svg: utf8.decode(data));
       }
     } else {
       return pdf.Image(await flutterImageProvider(entry.uriImage));