From 40c424104de1f12de0132a7dfc9ea46d110c364f Mon Sep 17 00:00:00 2001
From: Andrey Kiselev <dron@ak4719.spb.edu>
Date: Fri, 1 Jul 2005 12:35:18 +0000
Subject: [PATCH] Added open option 'h' to avoid reading the first IFD when
 needed. As per bug http://bugzilla.remotesensing.org/show_bug.cgi?id=875

---
 libtiff/tif_open.c | 16 +++++++++++++++-
 libtiff/tiffiop.h  |  4 +++-
 man/TIFFOpen.3tiff |  9 +++++++--
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/libtiff/tif_open.c b/libtiff/tif_open.c
index ea517d09..83cfd11e 100644
--- a/libtiff/tif_open.c
+++ b/libtiff/tif_open.c
@@ -1,4 +1,4 @@
-/* $Id: tif_open.c,v 1.25 2005-06-03 13:41:13 dron Exp $ */
+/* $Id: tif_open.c,v 1.26 2005-07-01 12:35:18 dron Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -222,6 +222,7 @@ TIFFClientOpen(
 	 * 'm'		disable use of memory-mapped files
 	 * 'C'		enable strip chopping support when reading
 	 * 'c'		disable strip chopping support
+	 * 'h'		read TIFF header only, do not load the first IFD
 	 *
 	 * The use of the 'l' and 'b' flags is strongly discouraged.
 	 * These flags are provided solely because numerous vendors,
@@ -296,6 +297,9 @@ TIFFClientOpen(
 			if (m == O_RDONLY)
 				tif->tif_flags &= ~TIFF_STRIPCHOP;
 			break;
+		case 'h':
+			tif->tif_flags |= TIFF_HEADERONLY;
+			break;
 		}
 	/*
 	 * Read in TIFF header.
@@ -378,6 +382,16 @@ TIFFClientOpen(
 	tif->tif_flags |= TIFF_MYBUFFER;
 	tif->tif_rawcp = tif->tif_rawdata = 0;
 	tif->tif_rawdatasize = 0;
+
+	/*
+	 * Sometimes we do not want to read the first directory (for example,
+	 * it may be broken) and want to proceed to other directories. I this
+	 * case we use the TIFF_HEADERONLY flag to open file and return
+	 * immediately after reading TIFF header.
+	 */
+	if (tif->tif_flags & TIFF_HEADERONLY)
+		return (tif);
+
 	/*
 	 * Setup initial directory.
 	 */
diff --git a/libtiff/tiffiop.h b/libtiff/tiffiop.h
index 4435c72d..103dc88b 100644
--- a/libtiff/tiffiop.h
+++ b/libtiff/tiffiop.h
@@ -1,4 +1,4 @@
-/* $Id: tiffiop.h,v 1.35 2005-06-29 10:21:35 dron Exp $ */
+/* $Id: tiffiop.h,v 1.36 2005-07-01 12:35:18 dron Exp $ */
 
 /*
  * Copyright (c) 1988-1997 Sam Leffler
@@ -109,6 +109,8 @@ struct tiff {
 #define	TIFF_INSUBIFD		0x2000	/* currently writing a subifd */
 #define	TIFF_UPSAMPLED		0x4000	/* library is doing data up-sampling */ 
 #define	TIFF_STRIPCHOP		0x8000	/* enable strip chopping support */
+#define	TIFF_HEADERONLY		0x10000	/* read header only, do not process */
+					/* the first directory */
 	toff_t		tif_diroff;	/* file offset of current directory */
 	toff_t		tif_nextdiroff;	/* file offset of following directory */
 	toff_t*		tif_dirlist;	/* list of offsets to already seen */
diff --git a/man/TIFFOpen.3tiff b/man/TIFFOpen.3tiff
index e30cb09b..f4209313 100644
--- a/man/TIFFOpen.3tiff
+++ b/man/TIFFOpen.3tiff
@@ -1,4 +1,4 @@
-.\" $Id: TIFFOpen.3tiff,v 1.1 2004-11-11 14:39:16 dron Exp $
+.\" $Id: TIFFOpen.3tiff,v 1.2 2005-07-01 12:36:22 dron Exp $
 .\"
 .\" Copyright (c) 1988-1997 Sam Leffler
 .\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
@@ -23,7 +23,7 @@
 .\" OF THIS SOFTWARE.
 .\"
 .if n .po 0
-.TH TIFFOpen 3TIFF "January 9, 1996" "libtiff"
+.TH TIFFOpen 3TIFF "July 1, 2005" "libtiff"
 .SH NAME
 TIFFOpen, TIFFFdOpen, TIFFClientOpen \- open a
 .SM TIFF
@@ -203,6 +203,11 @@ strip chopping.
 .TP
 .B c
 Disable the use of strip chopping when reading images.
+.TP
+.B h
+Read TIFF header only, do not load the first image directory. That could be
+useful in case of the broken first directory. We can open the file and proceed
+to the other directories.
 .SH "BYTE ORDER"
 The 
 .SM TIFF