1 files changed, 92 insertions, 16 deletions

diff --git a/src/photos/JfifSupport.vala b/src/photos/JfifSupport.vala
index 5ea64a5..0de45f8 100644
--- a/src/photos/JfifSupport.vala
+++ b/src/photos/JfifSupport.vala
@@ -103,17 +103,78 @@ public class JfifSniffer : GdkSniffer {
     }
     
     public override DetectedPhotoInformation? sniff(out bool is_corrupted) throws Error {
-        // Rely on GdkSniffer to detect corruption
         is_corrupted = false;
-        
-        if (!Jpeg.is_jpeg(file))
-            return null;
-        
-        DetectedPhotoInformation? detected = base.sniff(out is_corrupted);
-        if (detected == null)
+        if (!calc_md5) {
+            return fast_sniff (out is_corrupted);
+        } else {
+            if (!Jpeg.is_jpeg(file)) {
+                return null;
+            }
+
+            // Rely on GdkSniffer to detect corruption
+
+            DetectedPhotoInformation? detected = base.sniff(out is_corrupted);
+            if (detected == null)
+                return null;
+
+            return (detected.file_format == PhotoFileFormat.JFIF) ? detected : null;
+        }
+    }
+
+    private DetectedPhotoInformation? fast_sniff(out bool is_corrupted) throws Error {
+        is_corrupted = false;
+        var detected = new DetectedPhotoInformation();
+
+        detected.metadata = new PhotoMetadata();
+        try {
+            detected.metadata.read_from_file(file);
+        } catch (Error err) {
+            // no metadata detected
+            detected.metadata = null;
+        }
+
+        var fins = file.read(null);
+        var dins = new DataInputStream(fins);
+        dins.set_byte_order(DataStreamByteOrder.BIG_ENDIAN);
+        var seekable = (Seekable) dins;
+
+        var marker = Jpeg.Marker.INVALID;
+        var length = Jpeg.read_marker_2(dins, out marker);
+
+        if (marker != Jpeg.Marker.SOI) {
             return null;
-        
-        return (detected.file_format == PhotoFileFormat.JFIF) ? detected : null;
+        }
+
+        length = Jpeg.read_marker_2(dins, out marker);
+        while (!marker.is_sof() && length > 0) {
+            seekable.seek(length, SeekType.CUR, null);
+            length = Jpeg.read_marker_2(dins, out marker);
+        }
+
+        if (marker.is_sof()) {
+            if (length < 6) {
+                is_corrupted = true;
+                return null;
+            }
+
+            // Skip precision
+            dins.read_byte();
+
+            // Next two 16 bytes are image dimensions
+            uint16 height = dins.read_uint16();
+            uint16 width = dins.read_uint16();
+
+            detected.image_dim = Dimensions(width, height);
+            detected.colorspace = Gdk.Colorspace.RGB;
+            detected.channels = 3;
+            detected.bits_per_channel = 8;
+            detected.format_name = "jpeg";
+            detected.file_format = PhotoFileFormat.from_pixbuf_name(detected.format_name);
+        } else {
+            is_corrupted = true;
+        }
+
+        return detected;
     }
 }
 
@@ -159,6 +220,16 @@ namespace Jpeg {
         public uint8 get_byte() {
             return (uint8) this;
         }
+
+        public bool is_sof() {
+            // FFCn is SOF unless n is a multiple of 4 > 0 (FFC4, FFC8, FFCC)
+            if ((this & 0xC0) != 0xC0) {
+                return false;
+            }
+
+            var variant = this & 0x0F;
+            return variant == 0 || variant % 4 != 0;
+        }
     }
     
     public enum Quality {
@@ -219,12 +290,9 @@ namespace Jpeg {
         return is_jpeg_stream(mins);
     }
 
-    private int read_marker(InputStream fins, out Jpeg.Marker marker) throws Error {
+    private int32 read_marker_2(DataInputStream dins, out Jpeg.Marker marker) throws Error {
         marker = Jpeg.Marker.INVALID;
-        
-        DataInputStream dins = new DataInputStream(fins);
-        dins.set_byte_order(DataStreamByteOrder.BIG_ENDIAN);
-        
+
         if (dins.read_byte() != Jpeg.MARKER_PREFIX)
             return -1;
         
@@ -235,9 +303,10 @@ namespace Jpeg {
         }
         
         uint16 length = dins.read_uint16();
-        if (length < 2 && fins is Seekable) {
+        var seekable = dins as Seekable;
+        if (length < 2 && dins != null) {
             debug("Invalid length %Xh at ofs %" + int64.FORMAT + "Xh", length,
-                    (fins as Seekable).tell() - 2);
+                    seekable.tell() - 2);
             
             return -1;
         }
@@ -245,5 +314,12 @@ namespace Jpeg {
         // account for two length bytes already read
         return length - 2;
     }
+
+    private int read_marker(InputStream fins, out Jpeg.Marker marker) throws Error {
+        DataInputStream dins = new DataInputStream(fins);
+        dins.set_byte_order(DataStreamByteOrder.BIG_ENDIAN);
+
+        return read_marker_2(dins, out marker);
+    }
 }