Check NumberofDataArrays, warn only if it's wrong.

Author: Ben Cipollini

nibabel/gifti/parse_gifti_fast.py

@@ -10,6 +10,7 @@
 
 import base64
 import sys
+import warnings
 import zlib
 from ..externals.six import StringIO
 from xml.parsers.expat import ParserCreate, ExpatError
@@ -108,6 +109,8 @@ def StartElementHandler(self, name, attrs):
             self.img = GiftiImage()
             if 'Version' in attrs:
                 self.img.version = attrs['Version']
+            if 'NumberOfDataArrays' in attrs:
+                self.expected_numDA = int(attrs['NumberOfDataArrays'])
 
             self.fsm_state.append('GIFTI')
         elif name == 'MetaData':
@@ -204,6 +207,10 @@ def EndElementHandler(self, name):
         if DEBUG_PRINT:
             print('End element:\n\t', repr(name))
         if name == 'GIFTI':
+            if hasattr(self, 'expected_numDA') and self.expected_numDA != self.img.numDA:
+                warnings.warn("Actual # of data arrays does not match "
+                              "# expected: %d != %d." % (self.expected_numDA,
+                                                         self.img.numDA))
             # remove last element of the list
             self.fsm_state.pop()
             # assert len(self.fsm_state) == 0

nibabel/gifti/tests/test_giftiio.py

@@ -300,3 +300,23 @@ def test_labeltable_deprecations():
         warnings.filterwarnings('once', category=DeprecationWarning)
         img.set_labeltable(lt)
     assert_equal(lt, img.labeltable)
+
+
+def test_parse_dataarrays():
+    fn = 'bad_daa.gii'
+    img = gi.GiftiImage()
+
+    with InTemporaryDirectory():
+        gi.write(img, fn)
+        with open(fn, 'r') as fp:
+            txt = fp.read()
+        # Make a bad gifti.
+        txt = txt.replace('NumberOfDataArrays="0"', 'NumberOfDataArrays ="1"')
+        with open(fn, 'w') as fp:
+            fp.write(txt)
+
+        with clear_and_catch_warnings() as w:
+            warnings.filterwarnings('once', category=UserWarning)
+            gi.read(fn)
+            assert_equal(len(w), 1)
+            assert_equal(img.numDA, 0)