From 7076a54dfbcdbe62d64bfc472e8fbc7a1ff82285 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Basg=C3=B6ze?= <daniel.basgoeze@rwth-aachen.de>
Date: Wed, 15 Apr 2020 21:19:09 +0200
Subject: [PATCH] Add error checking to C style io

---
 .../storage/dd/sylvan/InternalSylvanAdd.cpp    | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/storm/storage/dd/sylvan/InternalSylvanAdd.cpp b/src/storm/storage/dd/sylvan/InternalSylvanAdd.cpp
index 2eddadd3a..5a3cdc954 100644
--- a/src/storm/storage/dd/sylvan/InternalSylvanAdd.cpp
+++ b/src/storm/storage/dd/sylvan/InternalSylvanAdd.cpp
@@ -803,16 +803,26 @@ namespace storm {
         void InternalAdd<DdType::Sylvan, ValueType>::exportToDot(std::string const& filename, std::vector<std::string> const&, bool) const {
             // Open the file, dump the DD and close it again.
             FILE* filePointer = fopen(filename.c_str() , "a+");
-            this->sylvanMtbdd.PrintDot(filePointer);
-            fclose(filePointer);
+            // fopen returns a nullptr on failure
+            if (filePointer == nullptr) {
+                STORM_LOG_ERROR("Failure to open file: " << filename);
+            } else {
+                this->sylvanMtbdd.PrintDot(filePointer);
+                fclose(filePointer);
+            }
         }
 
         template<typename ValueType>
         void InternalAdd<DdType::Sylvan, ValueType>::exportToText(std::string const& filename) const {
             // Open the file, dump the DD and close it again.
             FILE* filePointer = fopen(filename.c_str() , "a+");
-            this->sylvanMtbdd.PrintText(filePointer);
-            fclose(filePointer);
+            // fopen returns a nullptr on failure
+            if (filePointer == nullptr) {
+                STORM_LOG_ERROR("Failure to open file: " << filename);
+            } else {
+                this->sylvanMtbdd.PrintText(filePointer);
+                fclose(filePointer);
+            }
         }
 
         template<typename ValueType>