From 5df65ec6fdd5a5367dd6e1e274d6018a4d40904f Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Fri, 19 May 2017 16:07:36 +0100
Subject: [PATCH] fix tiff read with page > 0

could break edge tiles under some circumstances
---
 ChangeLog                   |  3 +++
 configure.ac                |  6 +++---
 libvips/foreign/tiff2vips.c | 19 +++++++++++++------
 3 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b9db7479..74587bcf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,6 @@
+19/5/17 started 8.5.6
+- tiff read with start page > 0 could break edge tiles or strips
+
 23/4/17 started 8.5.5
 - doc polishing
 - more improvements for truncated PNG files, thanks juyunsang 
diff --git a/configure.ac b/configure.ac
index 2bce35fc..10cf847a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@
 
 # also update the version number in the m4 macros below
 
-AC_INIT([vips], [8.5.5], [vipsip@jiscmail.ac.uk])
+AC_INIT([vips], [8.5.6], [vipsip@jiscmail.ac.uk])
 # required for gobject-introspection
 AC_PREREQ(2.62)
 
@@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # user-visible library versioning
 m4_define([vips_major_version], [8])
 m4_define([vips_minor_version], [5])
-m4_define([vips_micro_version], [5])
+m4_define([vips_micro_version], [6])
 m4_define([vips_version],
           [vips_major_version.vips_minor_version.vips_micro_version])
 
@@ -38,7 +38,7 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date`
 #   binary interface changes not backwards compatible?: reset age to 0
 
 LIBRARY_CURRENT=49
-LIBRARY_REVISION=4
+LIBRARY_REVISION=5
 LIBRARY_AGE=7
 
 # patched into include/vips/version.h
diff --git a/libvips/foreign/tiff2vips.c b/libvips/foreign/tiff2vips.c
index 87b187d9..7dffcb0b 100644
--- a/libvips/foreign/tiff2vips.c
+++ b/libvips/foreign/tiff2vips.c
@@ -173,6 +173,8 @@
  * 	- invalidate operation on read error
  * 27/1/17
  * 	- if rows_per_strip is large, read with scanline API instead
+ * 19/5/17
+ * 	- page > 0 could break edge tiles or strips
  */
 
 /*
@@ -1469,8 +1471,11 @@ rtiff_fill_region( VipsRegion *out, void *seq, void *a, void *b, gboolean *stop
 
 		x = 0;
 		while( x < r->width ) { 
-			int page_no = rtiff->page + (r->top + y) / 
-				rtiff->header.height;
+			/* page_no is within this toilet roll image, not tiff
+			 * file page number ... add the number of the start
+			 * page to get that.
+			 */
+			int page_no = (r->top + y) / rtiff->header.height;
 			int page_y = (r->top + y) % rtiff->header.height;
 
 			/* Coordinate of the tile on this page that xy falls in.
@@ -1478,7 +1483,7 @@ rtiff_fill_region( VipsRegion *out, void *seq, void *a, void *b, gboolean *stop
 			int xs = ((r->left + x) / tile_width) * tile_width;
 			int ys = (page_y / tile_height) * tile_height;
 
-			if( rtiff_set_page( rtiff, page_no ) ||
+			if( rtiff_set_page( rtiff, rtiff->page + page_no ) ||
 				rtiff_read_tile( rtiff, buf, xs, ys ) ) { 
 				VIPS_GATE_STOP( "rtiff_fill_region: work" ); 
 				return( -1 );
@@ -1744,9 +1749,11 @@ rtiff_stripwise_generate( VipsRegion *or,
 
 	y = 0;
 	while( y < r->height ) { 
-		/* Page number, position within this page.
+		/* page_no is within this toilet roll image, not tiff
+		 * file page number ... add the number of the start
+		 * page to get that.
 		 */
-		int page_no = rtiff->page + (r->top + y) / page_height;
+		int page_no = (r->top + y) / page_height;
 		int y_page = (r->top + y) % page_height;
 
 		/* Strip number.
@@ -1785,7 +1792,7 @@ rtiff_stripwise_generate( VipsRegion *or,
 
 		g_assert( hit.height > 0 ); 
 
-		if( rtiff_set_page( rtiff, page_no ) ) {
+		if( rtiff_set_page( rtiff, rtiff->page + page_no ) ) {
 			VIPS_GATE_STOP( "rtiff_stripwise_generate: work" ); 
 			return( -1 );
 		}