From ff21b5a9626546cb09a14a4ca1122d0bb8c6216c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Walenciak?= <Kicer86@gmail.com>
Date: Sun, 17 Sep 2017 18:17:03 +0200
Subject: [PATCH] restore position if necessary

---
 src/bigtiffimage.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/bigtiffimage.cpp b/src/bigtiffimage.cpp
index 709bb34d..76336638 100644
--- a/src/bigtiffimage.cpp
+++ b/src/bigtiffimage.cpp
@@ -396,11 +396,16 @@ namespace Exiv2
         return Image::AutoPtr(new BigTiffImage(io));
     }
 
-    bool isBigTiffType(BasicIo& io, bool)
+    bool isBigTiffType(BasicIo& io, bool advance)
     {
+        const long pos = io.tell();
         const Header header = readHeader(io);
+        const bool valid = header.isValid();
 
-        return header.isValid();
+        if (valid == false || advance == false)
+            io.seek(pos, BasicIo::beg);
+
+        return valid;
     }
 
 }