I’m working on polishing my mini_printf implementation and making a final,
verified and documented code release, and the thing I made work in the past
and something that stopped working when I moved to MacOSX was a randomized
stress-test.
https://github.com/wkoszek/mini_printf
It’s pretty neat: it uses its own PRNG generator to achieve repeatability
and uses its numbers to construct randomized format strings which are then
played against OSes printf() and my mini_printf() API. Both versions are
later compared. I exposed a lot of bugs in mini_printf that way, of which
all have been fixed.
So anyway: I refactored mini_printf to the state where I can show it to
other people. I also made the stress-test work on MacOSX, and I could play
1,000,000 random format string patterns with 0 failures in couple of
seconds. But the same code failed miserably on Linux.
It looks like my stressing testbench found a usability problem between
Linux and MacOSX printf. Problem shows up when you decide to use
unsupported format string specifier. While Linux leaves the % signs,
MacOSX doesn’t propagate them to the string. I guess I’ll have to find a way
to elegantly solve it, and preferably without any #defines.
wk:/w/repos/mini_printf> cat p.c #include <stdio.h>
int main() { printf("%k%k%k\n"); }
vagrant@vagrant-ubuntu-trusty-64:/vagrant/mini_printf$ ./p %k%k%k
wk:/w/repos/mini_printf> ./p kkk