openbsd: map si_addr inside struct siginfo_t

[semarie]

formally, under OpenBSD, si_addr is part of a C union. As we don't use
others members of the union inside struct siginfo_t, it should be safe
to directly map the field.

cc @mmcco

[alexcrichton]

Thanks! Due to the use of a union here in C it's a bit difficult to represent in Rust, so you may want to do something similar to what's currently defined on Linux. The size of the struct should be the same as C in both cases.

Better yet, if you could run cargo run inside of the libc-test directory on OpenBSD, it'll tell you whether you're right or wrong! (and I also suspect there may be a number of other failures)

[semarie]

I have added padding to match the size of the C struct.
I will try to get a running cargo to do the test. But I suspect it will take some times...

[semarie]

The pad value have been computed using C code:

#include <sys/siginfo.h>
#include <stdio.h>
#include <stdlib.h>
int main() {
  printf("pad = %llu\n", sizeof(siginfo_t) - 3*sizeof(int) - sizeof(void *));
  return 0;
}

siginfo definition: http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/sys/sys/siginfo.h?rev=1.11&content-type=text/x-cvsweb-markup

[mmcco]

@semarie Looks like a stray ksh error message found its way into that commit...

[semarie]

@MMCo thanks for pointing it.