From b5587ac2e49b79dc71cfe11bda4ea77a3a3b8392 Mon Sep 17 00:00:00 2001
From: Lee Howard <faxguy@howardsilvan.com>
Date: Sun, 14 Jun 2015 22:55:16 +0000
Subject: [PATCH] From Ludolf Holzheid on Bugzilla Bug #2498:

Attached is a patch that adds a configure option to select the file I/O style
on Windows hosts.

It defaults to --enable-win32-io on all windows targets other than Cygwin and
to --disable-win32-io on Cygwin, and thus should be backwards-compatible.

This allows programs using the Unix file I/O style (such as Netpbm's tifftopnm)
to link against libtiff if configured for e.g. MinGW.
---
 ChangeLog    |  4 ++++
 configure.ac | 15 +++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index dbcfe1d1..434d2fd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2015-06-14  Lee Howard  <faxguy@howardsilvan.com>
 
+	* configure: contribution from Ludolf Holzheid on Bugzilla
+	Bug #2498.  Adds an option to select the file I/O style on 
+	Windows hosts.
+
 	* libtiff/tif_getimage.c: contribution from Gary Cramblitt 
 	on Bugzilla Bug #2409.  Correct reading of certain tiled TIFFs.
 
diff --git a/configure.ac b/configure.ac
index 7c6459ab..608d41e0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -841,17 +841,28 @@ dnl this must be after the ogl test, since that looks for windows.h and we
 dnl test it
 dnl ---------------------------------------------------------------------------
 
+AC_ARG_ENABLE(win32-io,
+	      AS_HELP_STRING([--disable-win32-io],
+			     [disable Win32 I/O (Windows only, enabled by default except for Cygwin)]),,)
+
 win32_io_ok=no
 case "${host_os}" in
     cygwin*)
+        if test x"$ac_cv_header_windows_h" = xyes -a "x$enable_win32_io" = xyes ; then 
+            win32_io_ok=yes
+	fi
         ;;
     *)
-        if test x"$ac_cv_header_windows_h" = xyes; then 
+        if test x"$ac_cv_header_windows_h" = xyes -a ! "x$enable_win32_io" = xno ; then 
             win32_io_ok=yes
-	    AC_DEFINE(USE_WIN32_FILEIO,1,[define to use win32 IO system])
 	fi
         ;;
 esac
+
+if test "$win32_io_ok" = "yes" ; then
+    AC_DEFINE(USE_WIN32_FILEIO,1,[define to use win32 IO system])
+fi
+
 AM_CONDITIONAL([WIN32_IO], [test "$win32_io_ok" = yes])
 
 dnl ---------------------------------------------------------------------------