Fix review

Author: Poker-sang

src/ImageSharp/Formats/Png/Chunks/AnimationControl.cs

@@ -5,21 +5,25 @@
 
 namespace SixLabors.ImageSharp.Formats.Png.Chunks;
 
-internal record AnimationControl(
-    int NumberFrames,
-    int NumberPlays)
+internal readonly struct AnimationControl
 {
     public const int Size = 8;
 
+    public AnimationControl(int numberFrames, int numberPlays)
+    {
+        this.NumberFrames = numberFrames;
+        this.NumberPlays = numberPlays;
+    }
+
     /// <summary>
     /// Gets the number of frames
     /// </summary>
-    public int NumberFrames { get; } = NumberFrames;
+    public int NumberFrames { get; }
 
     /// <summary>
     /// Gets the number of times to loop this APNG.  0 indicates infinite looping.
     /// </summary>
-    public int NumberPlays { get; } = NumberPlays;
+    public int NumberPlays { get; }
 
     /// <summary>
     /// Writes the acTL to the given buffer.
@@ -38,6 +42,6 @@ public void WriteTo(Span<byte> buffer)
     /// <returns>The parsed acTL.</returns>
     public static AnimationControl Parse(ReadOnlySpan<byte> data)
         => new(
-            NumberFrames: BinaryPrimitives.ReadInt32BigEndian(data[..4]),
-            NumberPlays: BinaryPrimitives.ReadInt32BigEndian(data[4..8]));
+            numberFrames: BinaryPrimitives.ReadInt32BigEndian(data[..4]),
+            numberPlays: BinaryPrimitives.ReadInt32BigEndian(data[4..8]));
 }

src/ImageSharp/Formats/Png/Chunks/FrameControl.cs

@@ -86,32 +86,32 @@ public void Validate(PngHeader hdr)
     {
         if (this.XOffset < 0)
         {
-            throw new NotSupportedException($"Invalid XOffset. Expected >= 0. Was '{this.XOffset}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.XOffset, "Expected >= 0");
         }
 
         if (this.YOffset < 0)
         {
-            throw new NotSupportedException($"Invalid YOffset. Expected >= 0. Was '{this.YOffset}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.YOffset, "Expected >= 0");
         }
 
         if (this.Width <= 0)
         {
-            throw new NotSupportedException($"Invalid Width. Expected > 0. Was '{this.Width}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.Width, "Expected > 0");
         }
 
         if (this.Height <= 0)
         {
-            throw new NotSupportedException($"Invalid Height. Expected > 0. Was '{this.Height}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.Height, "Expected > 0");
         }
 
         if (this.XOffset + this.Width > hdr.Width)
         {
-            throw new NotSupportedException($"Invalid XOffset or Width. The sum > PngHeader.Width. Was '{this.XOffset + this.Width}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.XOffset, this.Width, $"The sum > {nameof(PngHeader)}.{nameof(PngHeader.Width)}");
         }
 
         if (this.YOffset + this.Height > hdr.Height)
         {
-            throw new NotSupportedException($"Invalid YOffset or Height. The sum > PngHeader.Height. Was '{this.YOffset + this.Height}'.");
+            PngThrowHelper.ThrowInvalidParameter(this.YOffset, this.Height, "The sum > PngHeader.Height");
         }
     }
 

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -34,12 +34,17 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
     private readonly Configuration configuration;
 
     /// <summary>
-    /// Gets or sets a value indicating whether the metadata should be ignored when the image is being decoded.
+    /// Whether the metadata should be ignored when the image is being decoded.
+    /// </summary>
+    private readonly uint maxFrames;
+
+    /// <summary>
+    /// Whether the metadata should be ignored when the image is being decoded.
     /// </summary>
     private readonly bool skipMetadata;
 
     /// <summary>
-    /// Gets or sets a value indicating whether to read the IHDR and tRNS chunks only.
+    /// Whether to read the IHDR and tRNS chunks only.
     /// </summary>
     private readonly bool colorMetadataOnly;
 
@@ -61,7 +66,7 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
     /// <summary>
     /// The png animation control.
     /// </summary>
-    private AnimationControl? animationControl;
+    private AnimationControl animationControl;
 
     /// <summary>
     /// The number of bytes per pixel.
@@ -116,6 +121,7 @@ public PngDecoderCore(DecoderOptions options)
     {
         this.Options = options;
         this.configuration = options.Configuration;
+        this.maxFrames = options.MaxFrames;
         this.skipMetadata = options.SkipMetadata;
         this.memoryAllocator = this.configuration.MemoryAllocator;
     }
@@ -124,6 +130,7 @@ internal PngDecoderCore(DecoderOptions options, bool colorMetadataOnly)
     {
         this.Options = options;
         this.colorMetadataOnly = colorMetadataOnly;
+        this.maxFrames = options.MaxFrames;
         this.skipMetadata = true;
         this.configuration = options.Configuration;
         this.memoryAllocator = this.configuration.MemoryAllocator;
@@ -139,6 +146,7 @@ internal PngDecoderCore(DecoderOptions options, bool colorMetadataOnly)
     public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken cancellationToken)
         where TPixel : unmanaged, IPixel<TPixel>
     {
+        uint frameCount = 0;
         ImageMetadata metadata = new();
         PngMetadata pngMetadata = metadata.GetPngMetadata();
         this.currentStream = stream;
@@ -174,10 +182,21 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
                             ReadGammaChunk(pngMetadata, chunk.Data.GetSpan());
                             break;
                         case PngChunkType.FrameControl:
+                            ++frameCount;
+                            if (frameCount == this.maxFrames)
+                            {
+                                break;
+                            }
+
                             currentFrame = null;
                             lastFrameControl = this.ReadFrameControlChunk(chunk.Data.GetSpan());
                             break;
                         case PngChunkType.FrameData:
+                            if (frameCount == this.maxFrames)
+                            {
+                                break;
+                            }
+
                             if (image is null)
                             {
                                 PngThrowHelper.ThrowMissingDefaultData();
@@ -290,6 +309,7 @@ public Image<TPixel> Decode<TPixel>(BufferedReadStream stream, CancellationToken
     /// <inheritdoc/>
     public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellationToken)
     {
+        uint frameCount = 0;
         ImageMetadata metadata = new();
         PngMetadata pngMetadata = metadata.GetPngMetadata();
         this.currentStream = stream;
@@ -331,9 +351,20 @@ public ImageInfo Identify(BufferedReadStream stream, CancellationToken cancellat
                             ReadGammaChunk(pngMetadata, chunk.Data.GetSpan());
                             break;
                         case PngChunkType.FrameControl:
+                            ++frameCount;
+                            if (frameCount == this.maxFrames)
+                            {
+                                break;
+                            }
+
                             lastFrameControl = this.ReadFrameControlChunk(chunk.Data.GetSpan());
                             break;
                         case PngChunkType.FrameData:
+                            if (frameCount == this.maxFrames)
+                            {
+                                break;
+                            }
+
                             if (this.colorMetadataOnly)
                             {
                                 goto EOF;

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -1077,7 +1077,7 @@ private void EncodePixels<TPixel>(ImageFrame<TPixel> pixels, IndexedImageFrame<T
     {
         int width = this.width;
         int height = this.height;
-        if (pixels.Metadata.TryGetAPngFrameMetadata(out PngFrameMetadata? pngMetadata))
+        if (pixels.Metadata.TryGetPngFrameMetadata(out PngFrameMetadata? pngMetadata))
         {
             width = pngMetadata.Width;
             height = pngMetadata.Height;