Improved some the file validation and normalised some exceptions.

bramp · Feb 1, 2024 · fec17b5 · fec17b5
1 parent 0eae972
commit fec17b5
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Showing 5 changed files with 18 additions and 6 deletions.
diff --git a/packages/pmtiles/lib/src/archive.dart b/packages/pmtiles/lib/src/archive.dart
@@ -283,6 +283,11 @@ class PmTilesArchive {
   static Future<PmTilesArchive> fromReadAt(ReadAt f) async {
     final headerAndRoot =
         await (await f.readAt(0, headerAndRootMaxLength)).toBytes();
+
+    if (headerAndRoot.length < headerLength) {
+      throw CorruptArchiveException('Header is too short.');
+    }
+
     final header = Header(
       ByteData.view(
         // Make a copy of the first headerLength (127) bytes.
@@ -297,7 +302,7 @@ class PmTilesArchive {
     }
 
     if (header.clustered == Clustered.notClustered) {
-      throw UnimplementedError('Unclustered archives are not supported.');
+      throw UnsupportedError('Unclustered archives.');
     }
 
     final root = Uint8List.view(
@@ -390,6 +395,6 @@ extension CompressionDecoder on Compression {
         // TODO Add support for the following:
         // Compression.brotli,
         // Compression.zstd,
-        _ => throw UnimplementedError('$this compression is not supported.'),
+        _ => throw UnsupportedError('$this compression.'),
       };
 }
diff --git a/packages/pmtiles/lib/src/exceptions.dart b/packages/pmtiles/lib/src/exceptions.dart
@@ -16,6 +16,6 @@ class CorruptArchiveException implements Exception {
 
   @override
   String toString() {
-    return 'CorruptArchive: $message';
+    return 'CorruptArchiveException: $message';
   }
 }
diff --git a/packages/pmtiles/lib/src/header.dart b/packages/pmtiles/lib/src/header.dart
@@ -8,7 +8,10 @@ import 'convert.dart';
 import 'exceptions.dart';
 import 'types.dart';
 
+// Minimum valid header length.
 const headerLength = 127;
+
+// Max header + root length.
 const headerAndRootMaxLength = 16384;
 
 /// PMTiles Header
@@ -89,7 +92,7 @@ class Header {
     }
 
     if (version != 3) {
-      throw UnsupportedError('Unsupported version "$version"');
+      throw UnsupportedError('Version "$version" files');
     }
 
     if (!strict) {

diff --git a/packages/pmtiles/lib/src/io.dart b/packages/pmtiles/lib/src/io.dart
@@ -11,6 +11,10 @@ export 'io_http.dart' if (dart.library.node) 'io_http_fake.dart';
 /// Simple interface so we can abstract reading from Files, or Http.
 abstract interface class ReadAt {
   /// Read [length] bytes from [offset].
+  ///
+  /// If offset+length is beyond the end of the file as many bytes as possible
+  /// are returned.
+  // TODO Test the edge case behaviours.
   Future<ByteStream> readAt(int offset, int length);
 
   /// Close any resources.

diff --git a/packages/pmtiles/lib/src/types.dart b/packages/pmtiles/lib/src/types.dart
@@ -30,7 +30,7 @@ extension TileTypeMime on TileType {
         TileType.jpeg => 'image/jpeg',
         TileType.webp => 'image/webp',
         TileType.avif => 'image/avif',
-        _ => throw UnimplementedError('Unknown tile type $this'),
+        _ => throw UnsupportedError('Unknown tile type $this'),
       };
 
   /// Returns the file extension for this tile type.
@@ -40,6 +40,6 @@ extension TileTypeMime on TileType {
         TileType.jpeg => 'jpg',
         TileType.webp => 'webp',
         TileType.avif => 'avif',
-        _ => throw UnimplementedError('Unknown tile type $this'),
+        _ => throw UnsupportedError('Unknown tile type $this'),
       };
 }