It wraps snprintf(3) so that it performs some steps that one might
forget, or might be prone to accidents:
- It calculates the size of the destination buffer, and makes sure it's
an array (otherwise, using sizeof(s) would be very bad).
- It calculates if there's truncation or an error, returning -1 if so.
BTW, this macro doesn't have any issues of double evaluation, because
sizeof() doesn't evaluate its argument (unless it's a VLA, but then the
static_assert(3) within NITEMS() makes sure VLAs are not allowed).
This macro is very similar to STRTCPY(), defined in
<lib/string/strtcpy.h>.
Signed-off-by: Alejandro Colomar <alx@kernel.org>
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