Description
POSIX defines the following fields on siginfo_t link:
int si_signo Signal number.
int si_code Signal code.
int si_errno If non-zero, an errno value associated with
this signal, as described in <errno.h>.
pid_t si_pid Sending process ID.
uid_t si_uid Real user ID of sending process.
void *si_addr Address of faulting instruction.
int si_status Exit value or signal.
long si_band Band event for SIGPOLL.
union sigval si_value Signal value.
Of particular interest to me are si_signo, si_code (which are already exposed everywhere), as well as si_pid and si_status. These allow asynchronously receiving the exit status of a child process via SIGCHLD.
However, on x86_64-unknown-netbsd (documented here) and x86_64-unknown-openbsd (undocumented but exists here) , these fields are not exposed in any way. on x86_64-unknown-linux-gnu they are exposed as unsafe methods, and on x86_64-unknown-freebsd, as regular struct fields and unsafe methods.
I understand that this is due to some implementations choosing to use unions, or having different struct field orders. It would be very helpful if there was a consistent, portable way to access them, or at the very least, expose them on those two targets.