writing to closed stdout (II): exit status

[kdevel]

On Monday, 16 December 2024 at 09:33:12 UTC, Kagamin wrote:
> On Sunday, 15 December 2024 at 19:41:00 UTC, kdevel wrote:
>> On Sunday, 15 December 2024 at 17:16:11 UTC, Paul Backus wrote:
>>> It's possible to get the full exit status from `waitid` [3],
>>
>> Actually not on my linux machine:
>
> Try ssi_status from signalfd.

Like this?

```c
#include <stdio.h>
#include <assert.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/signalfd.h>

int main ()
{
    int rc = fork ();
    assert (rc != -1);

    if (rc == 0) { /* child */
       sleep (1);
       _exit (-1);
    }
    else {
       sigset_t mask;
       sigemptyset(&mask);
       sigaddset(&mask, SIGCHLD);
       int sfd = signalfd (-1, &mask, 0);
       assert (sfd != -1);

       rc = sigprocmask (SIG_BLOCK, &mask, 0);
       assert (rc != -1);

       struct signalfd_siginfo sfds;
       ssize_t s = read (sfd, &sfds, sizeof sfds);
       assert (s == sizeof sfds);

       printf ("%x\n", sfds.ssi_status);
    }
    return 0;
}
```