jpeg cmyk write was not inverting

the change to vips_sink_disc() for vips2jpeg make CMYK write fail, argh

thanks to Ole for the report

ChangeLog

@@ -68,6 +68,7 @@
 - added VipsPool, got rid of floating refs again, argh
 - VIPS_EXEEXT is now part of the exported API
 - im_blend() also does sizealike, oops
+- jpeg write was not inverting CMYK, thanks Ole
 
 30/11/10 started 7.24.0
 - bump for new stable

TODO

@@ -1,3 +1,10 @@
+- icc import / export should cast their inputs, they insist on uchar etc. at
+  the moment
+
+
+- can we call vips7 funcs from the vips8 interface?
+
+
 - revisit orc conv
 
   use an 8.8 accumulator ... build the scale into the 8.8 coeffs ... no div at

libvips/format/im_vips2jpeg.c

@@ -38,6 +38,8 @@
  * 18/7/10
  * 	- collect im_vips2bufjpeg() output in a list of blocks ... we no
  * 	  longer overallocate or underallocate
+ * 8/7/11
+ * 	- oop CMYK write was not inverting, thanks Ole
  */
 
 /*
@@ -540,16 +542,16 @@ write_jpeg_block( REGION *region, Rect *area, void *a )
 	Write *write = (Write *) a;
 	int i;
 
-	/* We are running in a background thread. We need to catch longjmp()s
-	 * here instead.
-	 */
-	if( setjmp( write->eman.jmp ) ) 
-		return( -1 );
-
 	for( i = 0; i < area->height; i++ )
 		write->row_pointer[i] = (JSAMPROW) 
 			IM_REGION_ADDR( region, 0, area->top + i );
 
+	/* We are running in a background thread. We need to catch any
+	 * longjmp()s from jpeg_write_scanlines() here.
+	 */
+	if( setjmp( write->eman.jmp ) ) 
+		return( -1 );
+
 	jpeg_write_scanlines( &write->cinfo, write->row_pointer, area->height );
 
 	return( 0 );
@@ -609,8 +611,7 @@ write_vips( Write *write, int qfac, const char *profile )
 
 	/* Build VIPS output stuff now we know the image we'll be writing.
 	 */
-	if( !(write->row_pointer = 
-		IM_ARRAY( NULL, write->in->Ysize, JSAMPROW )) )
+	if( !(write->row_pointer = IM_ARRAY( NULL, in->Ysize, JSAMPROW )) )
 		return( -1 );
 
 	/* Rest to default. 
@@ -641,7 +642,7 @@ write_vips( Write *write, int qfac, const char *profile )
 
 	/* Write data. Note that the write function grabs the longjmp()!
 	 */
-	if( vips_sink_disc( write->in, write_jpeg_block, write ) )
+	if( vips_sink_disc( in, write_jpeg_block, write ) )
 		return( -1 );
 
 	/* We have to reinstate the setjmp() before we jpeg_finish_compress().