test suite passes

with all jpegload coming via VipsStreamInput

ChangeLog

@@ -16,6 +16,8 @@
 - add @interpretation and @format to rawload
 - nifti load/save uses double for all floating point metadata
 - add vips_error_buffer_copy()
+- add VipsStream ... a universal IO class for loaders and savers
+- jpegload uses the new IO class
 
 31/8/19 started 8.8.3
 - revert sharpen restoring the input colourspace

libvips/foreign/jpeg2vips.c

@@ -250,6 +250,26 @@ stream_fill_input_buffer( j_decompress_ptr cinfo )
 	return( TRUE );
 }
 
+static void
+skip_input_data( j_decompress_ptr cinfo, long num_bytes )
+{
+	Source *src = (Source *) cinfo->src;
+
+	if( num_bytes > 0 ) {
+		while (num_bytes > (long) src->pub.bytes_in_buffer) {
+			num_bytes -= (long) src->pub.bytes_in_buffer;
+			(void) (*src->pub.fill_input_buffer) (cinfo);
+
+			/* note we assume that fill_input_buffer will never 
+			 * return FALSE, so suspension need not be handled.
+			 */
+		}
+
+		src->pub.next_input_byte += (size_t) num_bytes;
+		src->pub.bytes_in_buffer -= (size_t) num_bytes;
+	}
+}
+
 static int
 readjpeg_open_input( ReadJpeg *jpeg )
 {
@@ -272,6 +292,7 @@ readjpeg_open_input( ReadJpeg *jpeg )
 		src->pub.init_source = stream_init_source;
 		src->pub.fill_input_buffer = stream_fill_input_buffer;
 		src->pub.resync_to_restart = jpeg_resync_to_restart; 
+		src->pub.skip_input_data = skip_input_data; 
 		src->pub.bytes_in_buffer = 0;
 		src->pub.next_input_byte = src->buf;
 	}

libvips/foreign/jpegload.c

@@ -197,8 +197,6 @@ vips_foreign_load_jpeg_stream_load( VipsForeignLoad *load )
 static gboolean
 vips_foreign_load_jpeg_stream_is_a( VipsStreamInput *input )
 {
-	printf( "vips_foreign_load_jpeg_stream_is_a:\n" );
-
 	return( vips__isjpeg_stream( input ) );
 }
 

libvips/iofuncs/stream.c

@@ -33,16 +33,19 @@
 
 /* TODO
  *
+ * - filename encoding
  * - memory output
  * - add mmapable descriptors
  * - add seekable descriptors
+ * - can we test for mmapable and seekable?
+ * - do we need eof?
  * - can we really change all behaviour in the subclass? will we need map and
  *   seek as well as read and rewind?
  */
 
 /*
- */
 #define VIPS_DEBUG
+ */
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>