Revert "FIX: Immutable buffers should not be set writeable"

This reverts commit 0a1ea75.

Author: effigies

nibabel/streamlines/tck.py

@@ -432,8 +432,10 @@ def _read(cls, fileobj, header, buffer_size=4):
                 for point_part in point_parts:
                     # Read floats.
                     pts = np.frombuffer(point_part, dtype=dtype)
+                    # Enforce ability to write to underlying bytes object
+                    pts.flags.writeable = True
                     # Convert data to little-endian if needed.
-                    yield pts.astype('<f4').reshape([-1, 3])
+                    yield pts.astype('<f4', copy=False).reshape([-1, 3])
 
                 n_streams += len(point_parts)
 

nibabel/streamlines/tests/test_trk.py

@@ -105,7 +105,8 @@ def trk_with_bytes(self, trk_key='simple_trk_fname', endian='<'):
         with open(DATA[trk_key], 'rb') as fobj:
             trk_bytes = fobj.read()
         dt = trk_module.header_2_dtype.newbyteorder(endian)
-        trk_struct = np.ndarray((1,), dt, buffer=trk_bytes).copy()
+        trk_struct = np.ndarray((1,), dt, buffer=trk_bytes)
+        trk_struct.flags.writeable = True
         return trk_struct, trk_bytes
 
     def test_load_file_with_wrong_information(self):

nibabel/volumeutils.py

@@ -538,13 +538,9 @@ def array_from_file(shape, in_dtype, infile, offset=0, order='F', mmap=True):
                           n_read,
                           getattr(infile, 'name', 'object')))
     arr = np.ndarray(shape, in_dtype, buffer=data_bytes, order=order)
-    if not needs_copy:
-        try:
-            arr.flags.writeable = True
-        except ValueError:
-            needs_copy = True
     if needs_copy:
-        arr = arr.copy()
+        return arr.copy()
+    arr.flags.writeable = True
     return arr