[gawk] Test return value of awk statement

I'm trying to figure out how I can test the return value of a printf
statement in an awk script.

printf "format", variable
if (condition==bad) {exit 1}               # if printf failed, exit

I have been unable to find what the "condition" in the pseudo-awk above
might be.

Or is it that awk's builtin's do not set a return value?

Thanks,
CJ