fix --fail option to jpegload

getting --fail on jpegload working means tilecache must terminate on tile
calc error

make openslideload not report tile calc errors, it might need a --fail
option too

see https://github.com/jcupitt/libvips/issues/474

libvips/conversion/tilecache.c

@@ -31,6 +31,8 @@
  * 	- cache minimisation is optional, see "persistent" flag
  * 26/8/14 Lovell
  * 	- free the hash table in _dispose()
+ * 11/7/16
+ * 	- terminate on tile calc error
  */
 
 /*
@@ -609,6 +611,9 @@ vips_tile_cache_gen( VipsRegion *or,
 	VipsTile *tile;
 	GSList *work;
 	GSList *p;
+	int result;
+
+	result = 0;
 
 	VIPS_GATE_START( "vips_tile_cache_gen: wait1" );
 
@@ -658,8 +663,6 @@ vips_tile_cache_gen( VipsRegion *or,
 			tile = (VipsTile *) p->data;
 
 			if( tile->state == VIPS_TILE_STATE_PEND ) {
-				int result;
-
 				tile->state = VIPS_TILE_STATE_CALC;
 
 				VIPS_DEBUG_MSG_RED( "vips_tile_cache_gen: "
@@ -688,11 +691,11 @@ vips_tile_cache_gen( VipsRegion *or,
 				}
 
 				/* If there was an error calculating this
-				 * tile, just warn and carry on.
+				 * tile, black it out and terminate
+				 * calculation. We have to stop so we can
+				 * support things like --fail on jpegload.
 				 *
-				 * This can happen with things like reading
-				 * .scn files via openslide. We don't want the
-				 * read to fail because of one broken tile.
+				 * Don't return early, we'd deadlock. 
 				 */
 				if( result ) {
 					VIPS_DEBUG_MSG_RED( 
@@ -707,6 +710,8 @@ vips_tile_cache_gen( VipsRegion *or,
 					vips_error_clear();
 
 					vips_region_black( tile->region );
+
+					*stop = TRUE;
 				}
 
 				tile->state = VIPS_TILE_STATE_DATA;
@@ -749,7 +754,7 @@ vips_tile_cache_gen( VipsRegion *or,
 
 	g_mutex_unlock( cache->lock );
 
-	return( 0 );
+	return( result );
 }
 
 static int

libvips/foreign/jpeg2vips.c

@@ -74,6 +74,8 @@
  * 	  memory for progressive jpg files
  * 26/5/16
  * 	- switch to new orientation tag
+ * 11/7/16
+ * 	- new --fail handling
  */
 
 /*
@@ -186,16 +188,10 @@ readjpeg_free( ReadJpeg *jpeg )
 	result = 0;
 
 	if( jpeg->eman.pub.num_warnings != 0 ) {
-		if( jpeg->fail ) {
-			vips_error( "VipsJpeg", "%s", vips_error_buffer() );
-			result = -1;
-		}
-		else {
-			vips_warn( "VipsJpeg", 
-				_( "read gave %ld warnings" ), 
-				jpeg->eman.pub.num_warnings );
-			vips_warn( NULL, "%s", vips_error_buffer() );
-		}
+		vips_warn( "VipsJpeg", 
+			_( "read gave %ld warnings" ), 
+			jpeg->eman.pub.num_warnings );
+		vips_warn( NULL, "%s", vips_error_buffer() );
 
 		/* Make the message only appear once.
 		 */
@@ -991,6 +987,25 @@ read_jpeg_generate( VipsRegion *or,
 	if( setjmp( jpeg->eman.jmp ) ) 
 		return( -1 );
 
+	/* If --fail is set, we make read fail on any warnings. This will stop
+	 * on any errors from the previous jpeg_read_scanlines().
+	 */
+	if( jpeg->eman.pub.num_warnings > 0 &&
+		jpeg->fail ) {
+		vips_error( "VipsJpeg", 
+			_( "read gave %ld warnings" ), 
+			jpeg->eman.pub.num_warnings );
+		vips_error( NULL, "%s", vips_error_buffer() );
+
+		/* Make the message only appear once.
+		 */
+		jpeg->eman.pub.num_warnings = 0;
+
+		*stop = TRUE;
+
+		return( -1 );
+	}
+
 	for( y = 0; y < r->height; y++ ) {
 		JSAMPROW row_pointer[1];
 

libvips/foreign/openslide2vips.c

@@ -47,6 +47,8 @@
  * 	- do argb -> rgba for associated as well 
  * 27/1/15
  * 	- unpremultiplication speedups for fully opaque/transparent pixels
+ * 11/7/16
+ * 	- just warn on tile read error
  */
 
 /*
@@ -471,14 +473,16 @@ vips__openslide_generate( VipsRegion *out,
 		rslide->level,
 		r->width, r->height ); 
 
+	/* Only warn on error: we don't want to make the whole image unreadable
+	 * because of one broken tile.
+	 *
+	 * FIXME ... add a --fail option like jpegload
+	 */
 	error = openslide_get_error( rslide->osr );
-	if( error ) {
-		vips_error( "openslide2vips", 
+	if( error ) 
+		vips_warn( "openslide2vips", 
 			_( "reading region: %s" ), error );
 
-		return( -1 );
-	}
-
 	/* Since we are inside a cache, we know buf must be continuous.
 	 */
 	argb2rgba( buf, n, bg );

libvips/foreign/vips2jpeg.c

@@ -227,7 +227,6 @@ write_new( VipsImage *in )
         write->cinfo.err = jpeg_std_error( &write->eman.pub );
 	write->eman.pub.error_exit = vips__new_error_exit;
 	write->eman.pub.output_message = vips__new_output_message;
-	write->eman.pub.output_message = vips__new_output_message;
 	write->eman.fp = NULL;
 	write->profile_bytes = NULL;
 	write->profile_length = 0;