Merge pull request #161 from camillol/camillo/readexc2

Fix exception propagation in readinto

indexed_gzip/indexed_gzip.pyx

@@ -835,16 +835,17 @@ cdef class _IndexedGzipFile:
         try:
 
             vbuf = <void *>pbuf.buf
-            with self.__file_handle(), nogil:
-                ret = zran.zran_read(index, vbuf, bufsz)
+            with self.__file_handle():
+                with nogil:
+                    ret = zran.zran_read(index, vbuf, bufsz)
+                exc = get_python_exception()
 
         # release the py_buffer
         finally:
             PyBuffer_Release(&pbuf)
 
         # see how the read went
         if ret == zran.ZRAN_READ_FAIL:
-            exc = get_python_exception()
             raise ZranError('zran_read returned error: {} (file: {})'
                             .format(ZRAN_ERRORS.ZRAN_READ[ret], self.errname)) from exc
 

indexed_gzip/tests/test_indexed_gzip.py

@@ -509,7 +509,8 @@ def test_read_beyond_end(concat, drop):
         os.remove(testfile)
 
 
-def test_read_exception(testfile, nelems):
+@pytest.mark.parametrize('use_readinto', [False, True])
+def test_read_exception(testfile, nelems, use_readinto):
     """When wrapping a python file object, if it raises an exception
     it should be preserved.
     """
@@ -539,10 +540,13 @@ def my_error_fn(*args, **kwargs):
         gzf = igzip._IndexedGzipFile(fileobj=f)
         f.read = my_error_fn
         try:
-            gzf.read(1)
+            if use_readinto:
+                ba = bytearray(1)
+                gzf.readinto(ba)
+            else:
+                gzf.read(1)
         except Exception as e:
-            assert (MY_ERROR in str(e) or MY_ERROR in str(e.__cause__),
-                    "Exception was not preserved; got {}".format(e))
+            assert MY_ERROR in str(e) or MY_ERROR in str(e.__cause__), "Exception was not preserved; got {}".format(e)
             del e
         else:
             assert False, "Expected an exception to be raised"