Potential Memory Leak

In src/constants.c, if the PyNumber_And call fails, the routine returns without disposing of allocated objects.

Enclosed is a patch that fixes this, while regularizing the handling of cleanup on errors in an easier-to-understand, more structured fashion, avoiding gotos. Even with explicitly spelling out PyErr_Occurred() calls everywhere, the code is still slightly shorter.

But I think a C extension library requires too much work for this kind of thing. A more complete binding for Fontconfig can be done in pure Python with much less code.

首先阅读 src/constants.c，并将其中 PyNumber_And 的失败路径与附加的补丁进行比较。确认在该失败情况下已分配的对象会被释放，并确认错误清理路径得到一致处理；当该例程在这些错误路径上不存在内存泄漏时，即可完成。