Address more comments.

Author: Robert D. Vincent

nibabel/externals/netcdf.py

@@ -212,10 +212,11 @@ def __init__(self, filename, mode='r', mmap=None, version=1):
                 mmap = True
         try:
             self.fp.seek(0, 2)
-            self.file_bytes = self.fp.tell()
-            self.fp.seek(0)
         except ValueError:
             self.file_bytes = -1 # Unknown file length (gzip).
+        else:
+            self.file_bytes = self.fp.tell()
+            self.fp.seek(0)
 
         self.use_mmap = mmap
         self.version_byte = version
@@ -606,7 +607,7 @@ def _read_var_array(self):
             else:  # not a record variable
                 # Calculate size to avoid problems with vsize (above)
                 a_size = reduce(mul, shape, 1) * size
-                if self.file_bytes >= 0 and begin_+a_size > self.file_bytes:
+                if self.file_bytes >= 0 and begin_ + a_size > self.file_bytes:
                     data = fromstring(b'\x00'*a_size, dtype=dtype_)
                 elif self.use_mmap:
                     mm = mmap(self.fp.fileno(), begin_+a_size, access=ACCESS_READ)
@@ -615,6 +616,9 @@ def _read_var_array(self):
                 else:
                     pos = self.fp.tell()
                     self.fp.seek(begin_)
+                    # Try to read file, which may fail because the data is
+                    # at or past the end of file. In that case, we treat
+                    # this data as zeros.
                     buf = self.fp.read(a_size)
                     if len(buf) < a_size:
                         buf = b'\x00'*a_size