SWIG：在Python和C之间传递字节

Question

我已经在网上搜索了一段时间，但在Python和C之间来回传递字节的正确方法是什么？我利用了SWIG文档中的示例：

C代码：

char* foo(char *buff, int size)
{
    return buff;
}

包装代码：

%include <pybuffer.i>

%pybuffer_binary(char *buff, int size);
char* foo(char *buff, int size);

错误：

example_wrap.c: In function ‘_wrap_foo’:
example_wrap.c:3385:19: error: ‘size’ undeclared (first use in this function)
     arg2 = (int) (size / sizeof(char));               
example_wrap.c:3385:19: note: each undeclared identifier is reported only once for each function it appears in
example_wrap.c:3387:12: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
   result = (char *)foo(arg1,arg2); 

编辑： 包括pybuffer.i：https://github.com/swig/swig/blob/master/Lib/python/pybuffer.i