diff --git a/internal/ceres/file.h b/internal/ceres/file.h
new file mode 100644
index 0000000..219b459
--- /dev/null
+++ b/internal/ceres/file.h
@@ -0,0 +1,53 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2015 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: keir@google.com (Keir Mierle)
+//
+// Simple file IO support. This is a portability shim.
+
+#ifndef CERES_INTERNAL_FILE_H_
+#define CERES_INTERNAL_FILE_H_
+
+#include <string>
+#include "ceres/internal/port.h"
+
+namespace ceres {
+namespace internal {
+
+void WriteStringToFileOrDie(const std::string &data,
+                            const std::string &filename);
+void ReadFileToStringOrDie(const std::string &filename, std::string *data);
+
+// Join two path components, adding a slash if necessary.  If basename is an
+// absolute path then JoinPath ignores dirname and simply returns basename.
+std::string JoinPath(const std::string& dirname, const std::string& basename);
+
+}  // namespace internal
+}  // namespace ceres
+
+#endif  // CERES_INTERNAL_FILE_H_