image/jpeg: distinguish between FormatError and UnsupportedError when

encountering unknown markers.

Change-Id: Ica86013308d69da2f5b486119235ff693135b2f1
Reviewed-on: https://go-review.googlesource.com/6393
Reviewed-by: David Symonds <dsymonds@golang.org>
Run-TryBot: David Symonds <dsymonds@golang.org>

diff --git a/src/image/jpeg/reader.go b/src/image/jpeg/reader.go
index 8fcb2e06c1168b3d4f90f1157525214ccacdfdf6..3e002e5e54169142e58bcb83180fc2cba514cd15 100644 (file)
--- a/src/image/jpeg/reader.go
+++ b/src/image/jpeg/reader.go
@@ -45,17 +45,17 @@ const (
 )
 
 const (
-       soiMarker  = 0xd8 // Start Of Image.
-       eoiMarker  = 0xd9 // End Of Image.
        sof0Marker = 0xc0 // Start Of Frame (Baseline).
        sof1Marker = 0xc1 // Start Of Frame (Extended Sequential).
        sof2Marker = 0xc2 // Start Of Frame (Progressive).
        dhtMarker  = 0xc4 // Define Huffman Table.
-       dqtMarker  = 0xdb // Define Quantization Table.
-       sosMarker  = 0xda // Start Of Scan.
-       driMarker  = 0xdd // Define Restart Interval.
        rst0Marker = 0xd0 // ReSTart (0).
        rst7Marker = 0xd7 // ReSTart (7).
+       soiMarker  = 0xd8 // Start Of Image.
+       eoiMarker  = 0xd9 // End Of Image.
+       sosMarker  = 0xda // Start Of Scan.
+       dqtMarker  = 0xdb // Define Quantization Table.
+       driMarker  = 0xdd // Define Restart Interval.
        comMarker  = 0xfe // COMment.
        // "APPlication specific" markers aren't part of the JPEG spec per se,
        // but in practice, their use is described at
@@ -560,6 +560,8 @@ func (d *decoder) decode(r io.Reader, configOnly bool) (image.Image, error) {
                default:
                        if app0Marker <= marker && marker <= app15Marker || marker == comMarker {
                                err = d.ignore(n)
+                       } else if marker < 0xc0 { // See Table B.1 "Marker code assignments".
+                               err = FormatError("unknown marker")
                        } else {
                                err = UnsupportedError("unknown marker")
                        }