If a function needs to maintain the state of some data over successive calls, such as a working buffer or a pointer, the caller should provide this data.
如果函数需要在一系列调用期间维持某些数据的状态，比如工作缓存或指针，那么调用者应该提供此数据。
2
This error occurs if a program passes an invalid pointer value or if the length of the buffer is too small.
如果程序传递了无效的指针值，或者如果缓冲区的长度太小会发生此错误。
3
This function accepts a pointer to a user space buffer, a pointer to a kernel buffer, and a length defined in bytes.