"locale"

fscanf

vsnprintf return value should be the number of needed characters instead
of the (truncated) number of characters that were actually written.

strtol and friends need overflow handling.

real regerror

real DNS errors (gai_strerror,hstrerror,...)

Try to improve code size and quality with __restrict__.

FPU exception handling (for mawk)

gethostbyname/gethostbyname2: move static hostent to dynamic buffer so
they can be free()d.

mkdtemp

res_mkquery should not assume op is QUERY

logging.