Optimize relative seeking with TIFFSetDirectory

1 files changed, 6 insertions, 1 deletions

diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index ef21f7f5..d4cc11d0 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -4067,8 +4067,11 @@ int TIFFReadDirectory(TIFF *tif)
 
     if (tif->tif_nextdiroff == 0)
     {
-        /* In this special case, tif_diroff needs also to be set to 0. */
+        /* In this special case, tif_diroff needs also to be set to 0.
+         * Furthermore, TIFFSetDirectory() needs to be switched to
+         * absolute stepping. */
         tif->tif_diroff = tif->tif_nextdiroff;
+        tif->tif_setdirectory_force_absolute = TRUE;
         return 0; /* last offset, thus no checking necessary */
     }
 
@@ -5131,6 +5134,8 @@ int TIFFReadCustomDirectory(TIFF *tif, toff_t diroff,
             } /*-- if (!dp->tdir_ignore) */
         }
     }
+    /* To be able to return from SubIFD or custom-IFD to main-IFD */
+    tif->tif_setdirectory_force_absolute = TRUE;
     if (dir)
         _TIFFfreeExt(tif, dir);
     return 1;