BUG: fix large file support on 32 bit systems

On linux large file support must be enabled and ftello used to avoid
overflows. The result must not be converted to a size_t, but a long
long.

1 files changed, 24 insertions, 0 deletions

diff --git a/numpy/lib/tests/test_format.py b/numpy/lib/tests/test_format.py
index b9be643c8..73b1e7c12 100644
--- a/numpy/lib/tests/test_format.py
+++ b/numpy/lib/tests/test_format.py
@@ -620,5 +620,29 @@ def test_bad_header():
     format.write_array_header_1_0(s, d)
     assert_raises(ValueError, format.read_array_header_1_0, s)
 
+
+def test_large_file_support():
+    from nose import SkipTest
+    # try creating a large sparse file
+    with tempfile.NamedTemporaryFile() as tf:
+        try:
+            import subprocess as sp
+            sp.check_call(["truncate", "-s", "5368709120", tf.name])
+        except:
+            raise SkipTest("Could not create 5GB large file")
+        # write a small array to the end
+        f = open(tf.name, "wb")
+        f.seek(5368709120)
+        d = np.arange(5)
+        np.save(f, d)
+        f.close()
+        # read it back
+        f = open(tf.name, "rb")
+        f.seek(5368709120)
+        r = np.load(f)
+        f.close()
+        assert_array_equal(r, d)
+
+
 if __name__ == "__main__":
     run_module_suite()