Fix for exporting fbx bigger than 2GB

code/Common/DefaultIOStream.cpp

@@ -52,6 +52,35 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 using namespace Assimp;
 
+namespace
+{
+    template<size_t sizeOfPointer>
+    size_t select_ftell(FILE* file)
+    {
+        return ::ftell(file);
+    }
+
+    template<size_t sizeOfPointer>
+    int select_fseek(FILE* file, int64_t offset, int origin)
+    {
+        return ::fseek(file, static_cast<long>(offset), origin);
+    }
+
+#if defined _WIN32 && (!defined __GNUC__ || __MSVCRT_VERSION__ >= 0x0601)
+    template<>
+    size_t select_ftell<8>(FILE* file)
+    {
+        return ::_ftelli64(file);
+    }
+
+    template<>
+    int select_fseek<8>(FILE* file, int64_t offset, int origin)
+    {
+        return ::_fseeki64(file, offset, origin);
+    }
+#endif
+}
+
 // ----------------------------------------------------------------------------------
 DefaultIOStream::~DefaultIOStream()
 {
@@ -93,7 +122,7 @@ aiReturn DefaultIOStream::Seek(size_t pOffset,
         aiOrigin_END == SEEK_END && aiOrigin_SET == SEEK_SET");
 
     // do the seek
-    return (0 == ::fseek(mFile, (long)pOffset,(int)pOrigin) ? AI_SUCCESS : AI_FAILURE);
+    return (0 == select_fseek<sizeof(void*)>(mFile, (int64_t)pOffset,(int)pOrigin) ? AI_SUCCESS : AI_FAILURE);
 }
 
 // ----------------------------------------------------------------------------------
@@ -102,7 +131,7 @@ size_t DefaultIOStream::Tell() const
     if (!mFile) {
         return 0;
     }
-    return ::ftell(mFile);
+    return select_ftell<sizeof(void*)>(mFile);
 }
 
 // ----------------------------------------------------------------------------------