From 6890db99f810d6703d51ee7a602d9efa18901c8e Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 11 Jun 2020 23:48:36 +0100
Subject: [PATCH] Only throw for multi SOF when fully decoding.

---
 src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs               | 5 +++++
 .../ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Images.cs  | 1 +
 .../Formats/Jpg/JpegDecoderTests.Metadata.cs                 | 1 +
 tests/ImageSharp.Tests/TestImages.cs                         | 1 +
 .../Input/Jpg/issues/issue-1221-identify-multi-frame.jpg     | 3 +++
 5 files changed, 11 insertions(+)
 create mode 100644 tests/Images/Input/Jpg/issues/issue-1221-identify-multi-frame.jpg

diff --git a/src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs b/src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs
index f8151141c..b4f37cd7f 100644
--- a/src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs
+++ b/src/ImageSharp/Formats/Jpeg/JpegDecoderCore.cs
@@ -812,6 +812,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg
         {
             if (this.Frame != null)
             {
+                if (metadataOnly)
+                {
+                    return;
+                }
+
                 JpegThrowHelper.ThrowInvalidImageContentException("Multiple SOF markers. Only single frame jpegs supported.");
             }
 
diff --git a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Images.cs b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Images.cs
index c91aad7e7..50198b9c4 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Images.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Images.cs
@@ -32,6 +32,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
                 TestImages.Jpeg.Issues.ExifGetString750Load,
                 TestImages.Jpeg.Issues.ExifGetString750Transform,
                 TestImages.Jpeg.Issues.BadSubSampling1076,
+                TestImages.Jpeg.Issues.IdentifyMultiFrame1211,
 
                 // LibJpeg can open this despite the invalid density units.
                 TestImages.Jpeg.Issues.Fuzz.ArgumentOutOfRangeException825B,
diff --git a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs
index 9b6643f7f..e37b26cdb 100644
--- a/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs
+++ b/tests/ImageSharp.Tests/Formats/Jpg/JpegDecoderTests.Metadata.cs
@@ -38,6 +38,7 @@ namespace SixLabors.ImageSharp.Tests.Formats.Jpg
             { true, TestImages.Jpeg.Baseline.Jpeg400, 8, false, false },
             { true, TestImages.Jpeg.Baseline.Snake, 24, true, true },
             { true, TestImages.Jpeg.Baseline.Jpeg420Exif, 24, true, false },
+            { true, TestImages.Jpeg.Issues.IdentifyMultiFrame1211, 24, true, true },
         };
 
         public static readonly TheoryData<string, int, int, PixelResolutionUnit> RatioFiles =
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 4b5dffdfd..fd5296c37 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -229,6 +229,7 @@ namespace SixLabors.ImageSharp.Tests
                 public const string IncorrectResize1006 = "Jpg/issues/issue1006-incorrect-resize.jpg";
                 public const string ExifResize1049 = "Jpg/issues/issue1049-exif-resize.jpg";
                 public const string BadSubSampling1076 = "Jpg/issues/issue-1076-invalid-subsampling.jpg";
+                public const string IdentifyMultiFrame1211 = "Jpg/issues/issue-1221-identify-multi-frame.jpg";
 
                 public static class Fuzz
                 {
diff --git a/tests/Images/Input/Jpg/issues/issue-1221-identify-multi-frame.jpg b/tests/Images/Input/Jpg/issues/issue-1221-identify-multi-frame.jpg
new file mode 100644
index 000000000..c034c9024
--- /dev/null
+++ b/tests/Images/Input/Jpg/issues/issue-1221-identify-multi-frame.jpg
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:93f5c637aca626a04471ebc990edf9e8d47896db60618cfb7c5360891071709a
+size 2263840