From 1f1715c086d8dcdf5165b19164af9aee7aa12e98 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dan=20=C4=8Cerm=C3=A1k?= <dan.cermak@cgc-instruments.com>
Date: Fri, 6 Oct 2017 00:37:43 +0200
Subject: =?UTF-8?q?Use=20nullptr=20check=20instead=20of=20assertion,=20by?=
 =?UTF-8?q?=20Rapha=C3=ABl=20Hertzog?=
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Source:
https://github.com/Exiv2/exiv2/issues/57#issuecomment-333086302

tc can be a null pointer when the TIFF tag is unknown (the factory
then returns an auto_ptr(0)) => as this can happen for corrupted
files, an explicit check should be used because an assertion can be
turned of in release mode (with NDEBUG defined)

This also fixes #57

diff --git a/src/tiffvisitor.cpp b/src/tiffvisitor.cpp
index 74f8d078..4ab733d4 100644
--- a/src/tiffvisitor.cpp
+++ b/src/tiffvisitor.cpp
@@ -1294,11 +1294,12 @@ namespace Exiv2 {
             }
             uint16_t tag = getUShort(p, byteOrder());
             TiffComponent::AutoPtr tc = TiffCreator::create(tag, object->group());
-            // The assertion typically fails if a component is not configured in
-            // the TIFF structure table
-            assert(tc.get());
-            tc->setStart(p);
-            object->addChild(tc);
+            if (tc.get()) {
+                tc->setStart(p);
+                object->addChild(tc);
+            } else {
+               EXV_WARNING << "Unable to handle tag " << tag << ".\n";
+            }
             p += 12;
         }