Fix #1047

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -1159,6 +1159,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <summary>
         /// Reads the cycle redundancy chunk from the data.
         /// </summary>
+        [MethodImpl(InliningOptions.ShortMethod)]
         private uint ReadChunkCrc()
         {
             uint crc = 0;
@@ -1174,6 +1175,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Skips the chunk data and the cycle redundancy chunk read from the data.
         /// </summary>
         /// <param name="chunk">The image format chunk.</param>
+        [MethodImpl(InliningOptions.ShortMethod)]
         private void SkipChunkDataAndCrc(in PngChunk chunk)
         {
             this.currentStream.Skip(chunk.Length);
@@ -1184,6 +1186,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// Reads the chunk data from the stream.
         /// </summary>
         /// <param name="length">The length of the chunk data to read.</param>
+        [MethodImpl(InliningOptions.ShortMethod)]
         private IManagedByteBuffer ReadChunkData(int length)
         {
             // We rent the buffer here to return it afterwards in Decode()
@@ -1200,6 +1203,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <exception cref="ImageFormatException">
         /// Thrown if the input stream is not valid.
         /// </exception>
+        [MethodImpl(InliningOptions.ShortMethod)]
         private PngChunkType ReadChunkType()
         {
             if (this.currentStream.Read(this.buffer, 0, 4) == 4)
@@ -1221,6 +1225,7 @@ namespace SixLabors.ImageSharp.Formats.Png
         /// <returns>
         /// Whether the length was read.
         /// </returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
         private bool TryReadChunkLength(out int result)
         {
             if (this.currentStream.Read(this.buffer, 0, 4) == 4)

src/ImageSharp/Formats/Png/PngThrowHelper.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 
 namespace SixLabors.ImageSharp.Formats.Png
@@ -17,13 +18,16 @@ namespace SixLabors.ImageSharp.Formats.Png
         [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowNoData() => throw new ImageFormatException("PNG Image does not contain a data chunk");
 
+        [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowInvalidChunkType() => throw new ImageFormatException("Invalid PNG data.");
 
         [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowInvalidChunkCrc(string chunkTypeName) => throw new ImageFormatException($"CRC Error. PNG {chunkTypeName} chunk is corrupt!");
 
+        [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowNotSupportedColor() => new NotSupportedException("Unsupported PNG color type");
 
+        [MethodImpl(InliningOptions.ColdPath)]
         public static void ThrowUnknownFilter() => throw new ImageFormatException("Unknown filter type.");
     }
 }

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.Chunks.cs

@@ -54,7 +54,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
         [InlineData((uint)PngChunkType.Header)] // IHDR
         [InlineData((uint)PngChunkType.Palette)] // PLTE
         // [InlineData(PngChunkTypes.Data)] //TODO: Figure out how to test this
-        [InlineData((uint)PngChunkType.End)] // IEND
         public void Decode_IncorrectCRCForCriticalChunk_ExceptionIsThrown(uint chunkType)
         {
             string chunkName = GetChunkTypeName(chunkType);
@@ -74,26 +73,6 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             }
         }
 
-        [Theory]
-        [InlineData((uint)PngChunkType.Gamma)] // gAMA
-        [InlineData((uint)PngChunkType.Transparency)] // tRNS
-        [InlineData((uint)PngChunkType.Physical)] // pHYs: It's ok to test physical as we don't throw for duplicate chunks.
-        //[InlineData(PngChunkTypes.Text)] //TODO: Figure out how to test this
-        public void Decode_IncorrectCRCForNonCriticalChunk_ExceptionIsThrown(uint chunkType)
-        {
-            string chunkName = GetChunkTypeName(chunkType);
-
-            using (var memStream = new MemoryStream())
-            {
-                WriteHeaderChunk(memStream);
-                WriteChunk(memStream, chunkName);
-                WriteDataChunk(memStream);
-
-                var decoder = new PngDecoder();
-                decoder.Decode<Rgb24>(null, memStream);
-            }
-        }
-
         private static string GetChunkTypeName(uint value)
         {
             var data = new byte[4];

tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs

@@ -4,11 +4,11 @@
 // ReSharper disable InconsistentNaming
 
 using System.IO;
-
+using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
-
+using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
 using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Formats.Png
@@ -42,6 +42,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             TestImages.Png.Bad.ZlibOverflow,
             TestImages.Png.Bad.ZlibOverflow2,
             TestImages.Png.Bad.ZlibZtxtBadHeader,
+            TestImages.Png.Bad.Issue1047_BadEndChunk
         };
 
         public static readonly string[] TestImages48Bpp =
@@ -90,7 +91,15 @@ namespace SixLabors.ImageSharp.Tests.Formats.Png
             using (Image<TPixel> image = provider.GetImage(new PngDecoder()))
             {
                 image.DebugSave(provider);
-                image.CompareToOriginal(provider, ImageComparer.Exact);
+
+                if (provider.Utility.SourceFileOrDescription == TestImages.Png.Bad.Issue1047_BadEndChunk)
+                {
+                    image.CompareToOriginal(provider, ImageComparer.Exact, (IImageDecoder)SystemDrawingReferenceDecoder.Instance);
+                }
+                else
+                {
+                    image.CompareToOriginal(provider, ImageComparer.Exact);
+                }
             }
         }
 

tests/ImageSharp.Tests/TestImages.cs

@@ -99,6 +99,7 @@ namespace SixLabors.ImageSharp.Tests
                 public const string ZlibOverflow = "Png/zlib-overflow.png";
                 public const string ZlibOverflow2 = "Png/zlib-overflow2.png";
                 public const string ZlibZtxtBadHeader = "Png/zlib-ztxt-bad-header.png";
+                public const string Issue1047_BadEndChunk = "Png/issues/Issue_1047.png";
             }
 
             public static readonly string[] All =