Merge pull request numpy#11522 from jzwinck/fix-load-empty-npz

juliantaylor · web-flow · commit e3c28430efb1 · 2018-07-29T17:58:37.000+02:00
BUG: fix np.load() of empty .npz file
diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
@@ -412,12 +412,13 @@ def load(file, mmap_mode=None, allow_pickle=True, fix_imports=True,
     try:
         # Code to distinguish from NumPy binary files and pickles.
         _ZIP_PREFIX = b'PK\x03\x04'
+        _ZIP_SUFFIX = b'PK\x05\x06' # empty zip files start with this
         N = len(format.MAGIC_PREFIX)
         magic = fid.read(N)
         # If the file size is less than N, we need to make sure not
         # to seek past the beginning of the file
         fid.seek(-min(N, len(magic)), 1)  # back-up
-        if magic.startswith(_ZIP_PREFIX):
+        if magic.startswith(_ZIP_PREFIX) or magic.startswith(_ZIP_SUFFIX):
             # zip-file (assume .npz)
             # Transfer file ownership to NpzFile
             tmp = own_fid
diff --git a/numpy/lib/tests/test_format.py b/numpy/lib/tests/test_format.py
@@ -852,3 +852,10 @@ def test_large_archive():
         new_a = np.load(f)["arr"]
 
     assert_(a.shape == new_a.shape)
+
+
+def test_empty_npz():
+    # Test for gh-9989
+    fname = os.path.join(tempdir, "nothing.npz")
+    np.savez(fname)
+    np.load(fname)
