2016.12.13 08:54 "Re: [Tiff] one little ill-advised change in v4.0.7 broke functionality for HylaFAX", by Even Rouault

Lee,

sorry for the inconvenience. I'm all for reverting if that broke things of course, but even with your explanations and looking at the code, I don't understand how it may affect external software.

My grep'ing of the code shows that the TIFFFaxTabEnt structure and the 3 tables TIFFFaxMainTable, TIFFFaxWhiteTable and TIFFFaxBlackTable are only used by tif_fax3.h, tif_fax3.c & tif_fax3sm.c. And I don't see any connection at all with TIFFTAG_FAXRECVPARAMS, which has no specific (AFAICS) processing in libtiff.

Am I missing something or is it HylaFAX that uses libtiff internals in some ways?

Even

On lundi 12 décembre 2016 20:56:49 CET Lee Howard wrote:

See:

http://bugzilla.maptools.org/show_bug.cgi?id=2636

---------------------------------------------------------

So, for a few weeks now a couple of folks on the HylaFAX mailing lists have complained that HylaFAX does not work for them after they upgrade to libtiff v4.0.7. After looking into it I have found the culprit...

*******************************************************************

Index: ChangeLog
===================================================================
RCS file: /cvs/maptools/cvsroot/libtiff/ChangeLog,v
retrieving revision 1.1109
retrieving revision 1.1110
diff -u -r1.1109 -r1.1110

--- ChangeLog   3 Jan 2016 10:01:25 -0000    1.1109
+++ ChangeLog   9 Jan 2016 22:19:21 -0000    1.1110

@@ -1,3 +1,8 @@
+2016-01-09 Even Rouault <even.rouault at spatialys.com>
+

+    * libtiff/tif_fax3.h: make Param member of TIFFFaxTabEnt structure
+    a uint16 to reduce size of the binary.

+
  2016-01-03 Even Rouault <even.rouault at spatialys.com>

         * libtiff/tif_read.c, tif_dirread.c: fix indentation issues raised

Index: libtiff/tif_fax3.h

=================================================================== RCS file: /cvs/maptools/cvsroot/libtiff/libtiff/tif_fax3.h,v retrieving revision 1.9

retrieving revision 1.10
diff -u -r1.9 -r1.10

--- libtiff/tif_fax3.h  10 Mar 2011 20:23:07 -0000    1.9

+++ libtiff/tif_fax3.h  9 Jan 2016 22:19:21 -0000    1.10

@@ -1,4 +1,4 @@

-/* $Id: tif_fax3.h,v 1.9 2011-03-10 20:23:07 fwarmerdam Exp $ */ +/* $Id: tif_fax3.h,v 1.10 2016-01-09 22:19:21 erouault Exp $ */

  /*
   * Copyright (c) 1990-1997 Sam Leffler
@@ -84,7 +84,7 @@
  typedef struct { /* state table entry */

         unsigned char State;    /* see above */
         unsigned char Width;    /* width of code in bits */

-    uint32 Param;           /* unsigned 32-bit run length in bits */
+    uint16 Param;           /* unsigned 16-bit run length in bits */

  } TIFFFaxTabEnt;

  extern const TIFFFaxTabEnt TIFFFaxMainTable[];

*******************************************************************

I cannot see this change to reduce the size of the binary being discussed at all on the libtiff mailing list... and unfortunately I did not test libtiff CVS code in HylaFAX this year until now.

Anyway, the "Param" field here in TIFFFaxTabEnt corresponds to TIFFTAG_FAXRECVPARAMS which elsewhere in libtiff (like libtiff/tif_dirinfo.c) is known to be 32-bits long.

The consequence of this change is that any software that utilizes TIFFTAG_FAXRECVPARAMS (and HylaFAX does so quite heavily) will likely see their "params" data corrupted/lost... leading to all sorts of problems with image data operations.

Please reverse the attached patch.

--
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