closes https://github.com/assimp/assimp/issues/901

code/DefaultIOStream.cpp

@@ -55,6 +55,7 @@ DefaultIOStream::~DefaultIOStream()
 {
     if (mFile) {
         ::fclose(mFile);
+        mFile = nullptr;
     }
 }
 
@@ -111,7 +112,7 @@ size_t DefaultIOStream::FileSize() const
 
     if (SIZE_MAX == cachedSize) {
 
-        // Although fseek/ftell would allow us to reuse the exising file handle here,
+        // Although fseek/ftell would allow us to reuse the existing file handle here,
         // it is generally unsafe because:
         //  - For binary streams, it is not technically well-defined
         //  - For text files the results are meaningless
@@ -125,12 +126,14 @@ size_t DefaultIOStream::FileSize() const
         if (0 != err)
             return 0;
         cachedSize = (size_t) (fileStat.st_size);
-#else
+#elif defined __gnu_linux__
         struct stat fileStat;
         int err = stat(mFilename.c_str(), &fileStat );
         if (0 != err)
             return 0;
         cachedSize = (size_t) (fileStat.st_size);
+#else
+#   error "Unknown platform"
 #endif
     }
     return cachedSize;

test/unit/utDefaultIOStream.cpp

@@ -52,13 +52,25 @@ public:
         // empty
     }
 
+    TestDefaultIOStream( FILE* pFile, const std::string &strFilename )
+    : DefaultIOStream( pFile, strFilename ) {
+        // empty
+    }
+
     virtual ~TestDefaultIOStream() {
         // empty
     }
 };
 
 TEST_F( utDefaultIOStream, FileSizeTest ) {
-    TestDefaultIOStream myStream;
+    char buffer[ L_tmpnam ];
+    tmpnam( buffer );
+    std::FILE *fs( std::fopen( buffer, "w+" ) );
+    size_t written( std::fwrite( buffer, 1, sizeof( char ) * L_tmpnam, fs ) );
+    std::fflush( fs );
+
+    TestDefaultIOStream myStream( fs, buffer );
     size_t size = myStream.FileSize();
-    EXPECT_EQ( size, 0 );
+    EXPECT_EQ( size, sizeof( char ) * L_tmpnam );
+    remove( buffer );
 }