Issue #132: Handle undefined EXIF data type where no number of components set

src/ImageSharp/MetaData/Profiles/Exif/ExifReader.cs

@@ -319,6 +319,13 @@ namespace ImageSharp
 
             uint numberOfComponents = this.GetLong();
 
+            // Issue #132: ExifDataType == Undefined is treated like a byte array.
+            // If numberOfComponents == 0 this value can only be handled as an inline value and must fallback to 4 (bytes)
+            if (dataType == ExifDataType.Undefined && numberOfComponents == 0)
+            {
+                numberOfComponents = 4;
+            }
+
             uint size = numberOfComponents * ExifValue.GetSize(dataType);
             byte[] data = this.GetBytes(4);
 

tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs

@@ -7,9 +7,11 @@ namespace ImageSharp.Tests
 {
     using System;
     using System.Collections;
+    using System.Collections.Generic;
     using System.IO;
     using System.Linq;
     using System.Text;
+    using ImageSharp.Processing;
     using Xunit;
 
     public class ExifProfileTests
@@ -268,6 +270,26 @@ namespace ImageSharp.Tests
             }
         }
 
+        [Fact]
+        public void ExifTypeUndefined()
+        {
+            Image image = TestFile.Create(TestImages.Jpeg.Baseline.Bad.ExifUndefType).CreateImage();
+            Assert.NotNull(image);
+
+            ExifProfile profile = image.MetaData.ExifProfile;
+            Assert.NotNull(profile);
+
+            IEnumerator<ExifValue> enumerator = profile.Values.GetEnumerator();
+            while (enumerator.MoveNext())
+            {
+                ExifValue entry = enumerator.Current;
+                if (entry.DataType == ExifDataType.Undefined)
+                {
+                    Assert.NotEqual(0, entry.NumberOfComponents);
+                }
+            }
+        }
+
         private static ExifProfile GetExifProfile()
         {
             Image image = TestFile.Create(TestImages.Jpeg.Baseline.Floorplan).CreateImage();

tests/ImageSharp.Tests/TestImages.cs

@@ -61,6 +61,7 @@ namespace ImageSharp.Tests
                 public static class Bad
                 {
                     public const string MissingEOF = "Jpg/baseline/badeof.jpg";
+                    public const string ExifUndefType = "Jpg/baseline/ExifUndefType.jpg";
                 }
 
                 public const string Cmyk = "Jpg/baseline/cmyk.jpg";