ringbuffer.c - improper use of memcpy return value

[missblit]

In ringbuffer.c, and in exercise 44 of LCTHW, you have a couple instances similar to:

void *result = memcpy(buffer->buffer + buffer->end, data, length);
check(result != NULL, "Failed to write data into buffer.");

However, memcpy merely returns 'dest'. The return value is not indicative of success or failure in any way. Checking it against null is harmless but seems like a bug, and may mislead readers as to how memcpy works.

I was alerted to this issue in the comments section of a recent Hacker News post: https://news.ycombinator.com/item?id=8059283