strscpy copies the src string, or as much of it as fits, into the dst
buffer. The dst buffer is always NUL terminated, unless it's zero-sized.
strscpy returns the number of characters copied (not including the
trailing NUL) or -E2BIG if len is 0 or src was truncated.

Currently drm-kmod replaces strscpy with strncpy that is not quite
correct as strncpy does not NUL-terminate overflown strings and returns
different values on exit.