Break out after SOS marker

src/ImageSharp/Formats/Jpeg/GolangPort/OrigJpegDecoderCore.cs

@@ -191,7 +191,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
             where TPixel : struct, IPixel<TPixel>
         {
             this.ParseStream(stream);
-
             return this.PostProcessIntoImage<TPixel>();
         }
 
@@ -202,7 +201,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
         public IImageInfo Identify(Stream stream)
         {
             this.ParseStream(stream, true);
-
             return new ImageInfo(new PixelTypeInfo(this.BitsPerPixel), this.ImageWidth, this.ImageHeight, this.MetaData);
         }
 
@@ -361,11 +359,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
 
                         break;
                     case OrigJpegConstants.Markers.SOS:
-                        if (metadataOnly)
-                        {
-                            this.InputProcessor.Skip(remaining);
-                        }
-                        else
+                        if (!metadataOnly)
                         {
                             this.ProcessStartOfScanMarker(remaining);
                             if (this.InputProcessor.ReachedEOF)
@@ -374,8 +368,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.GolangPort
                                 processBytes = false;
                             }
                         }
+                        else
+                        {
+                            // It's highly unlikely that APPn related data will be found after the SOS marker
+                            // We should have gathered everything we need by now.
+                            processBytes = false;
+                        }
 
                         break;
+
                     case OrigJpegConstants.Markers.DRI:
                         if (metadataOnly)
                         {

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/PdfJsScanDecoder.cs

@@ -412,19 +412,19 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private bool TryReadBit(DoubleBufferedStreamReader stream, out int bits)
+        private bool TryReadBit(DoubleBufferedStreamReader stream, out int bit)
         {
             if (this.bitsCount == 0)
             {
                 if (!this.TryFillBits(stream))
                 {
-                    bits = 0;
+                    bit = 0;
                     return false;
                 }
             }
 
             this.bitsCount--;
-            bits = (this.bitsData >> this.bitsCount) & 1;
+            bit = (this.bitsData >> this.bitsCount) & 1;
             return true;
         }
 

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegDecoderCore.cs

@@ -185,6 +185,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             where TPixel : struct, IPixel<TPixel>
         {
             this.ParseStream(stream);
+            this.AssignResolution();
             return this.PostProcessIntoImage<TPixel>();
         }
 
@@ -195,6 +196,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         public IImageInfo Identify(Stream stream)
         {
             this.ParseStream(stream, true);
+            this.AssignResolution();
             return new ImageInfo(new PixelTypeInfo(this.BitsPerPixel), this.ImageWidth, this.ImageHeight, this.MetaData);
         }
 
@@ -244,17 +246,18 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                             break;
 
                         case PdfJsJpegConstants.Markers.SOS:
-                            if (metadataOnly)
+                            if (!metadataOnly)
                             {
-                                this.InputStream.Skip(remaining);
+                                this.ProcessStartOfScanMarker();
+                                break;
                             }
                             else
                             {
-                                this.ProcessStartOfScanMarker();
+                                // It's highly unlikely that APPn related data will be found after the SOS marker
+                                // We should have gathered everything we need by now.
+                                return;
                             }
 
-                            break;
-
                         case PdfJsJpegConstants.Markers.DHT:
                             if (metadataOnly)
                             {
@@ -331,11 +334,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
                 // Read on.
                 fileMarker = FindNextFileMarker(this.markerBuffer, this.InputStream);
             }
-
-            this.ImageWidth = this.Frame.SamplesPerLine;
-            this.ImageHeight = this.Frame.Scanlines;
-            this.ComponentCount = this.Frame.ComponentCount;
-            this.AssignResolution();
         }
 
         /// <inheritdoc/>
@@ -389,6 +387,9 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// </summary>
         private void AssignResolution()
         {
+            this.ImageWidth = this.Frame.SamplesPerLine;
+            this.ImageHeight = this.Frame.Scanlines;
+
             if (this.jFif.XDensity > 0 && this.jFif.YDensity > 0)
             {
                 this.MetaData.HorizontalResolution = this.jFif.XDensity;
@@ -633,6 +634,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
             int maxV = 0;
             int index = 6;
 
+            this.ComponentCount = this.Frame.ComponentCount;
             if (!metadataOnly)
             {
                 // No need to pool this. They max out at 4