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>
These functions consume a source string. Document that. There's no way
to mark that they also produce a string in dst, though. That will be up
to the static analyzer to guess.
Signed-off-by: Alejandro Colomar <alx@kernel.org>
By writing the terminating null byte via stpcpy(3), we take advantage of
_FORTIFY_SOURCE for the last byte, which was unprotected before this
commit.
Reported-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Alejandro Colomar