Ensure buffer release before return

After reading data into a buffer the reading_generator_next function
calls invokes the underlying yajl parsing routine, which might return
successfully or not. There was a memory leak in the latter case, since
the "view" Py_buffer object was not being released before checking for
NULL returns and returning NULL ourselves.

This commit fixes the bug by ensuring we release the "view" object
before any returns, ensuring memory isn't leaked.

This was originally reported in #97.

Signed-off-by: Rodrigo Tobar <rtobar@icrar.org>

CHANGELOG.md

@@ -3,6 +3,9 @@
 ## Development
 
 * Added support for Python 3.12.
+* Fixed a memory leak in the ``yajl2_c`` backend
+  triggered only when the underlying ``yajl`` functions
+  reported a failure (#97).
 
 ## [3.2.0.post0]
 

ijson/backends/yajl2_c/reading_generator.c

@@ -74,6 +74,7 @@ PyObject *reading_generator_next(reading_generator_t *self)
 			length = view.len;
 			PyObject *send_res = ijson_yajl_parse(basic_parse_basecoro->h, view.buf, view.len);
 			Py_DECREF(pbuffer);
+			PyBuffer_Release(&view);
 			N_N(send_res);
 		}
 		else {
@@ -84,9 +85,10 @@ PyObject *reading_generator_next(reading_generator_t *self)
 			N_M1(length);
 			Py_DECREF(plength);
 			N_M1(PyObject_GetBuffer(self->buffer, &view, PyBUF_SIMPLE));
-			N_N(ijson_yajl_parse(basic_parse_basecoro->h, view.buf, length));
+			PyObject *send_res = ijson_yajl_parse(basic_parse_basecoro->h, view.buf, length);
+			PyBuffer_Release(&view);
+			N_N(send_res);
 		}
-		PyBuffer_Release(&view);
 		nevents = PyList_Size(events);
 
 		if (length == 0) {