1#include <errno.h>
2#include <string.h>
3#include <stdlib.h>
4#include <stdio.h>
5#include <unistd.h>
6#include <sys/types.h>
7#include <sys/wait.h>
8
9#ifdef __FreeBSD__
10#include <sys/procdesc.h>
11#endif
12
13#ifdef __linux__
14#include <sys/syscall.h>
15int pdfork(int *fd, int flags) {
16  return syscall(__NR_pdfork, fd, flags);
17}
18#endif
19
20int main() {
21  int procfd;
22  int rc =  pdfork(&procfd, 0);
23  if (rc < 0) {
24    fprintf(stderr, "pdfork() failed rc=%d errno=%d %s\n", rc, errno, strerror(errno));
25    exit(1);
26  }
27  if (rc == 0) { // Child process
28    sleep(1);
29    exit(123);
30  }
31  fprintf(stderr, "pdfork()ed child pid=%ld procfd=%d\n", (long)rc, procfd);
32  sleep(2);  // Allow child to complete
33  pid_t child = waitpid(-1, &rc, WNOHANG);
34  if (child == 0) {
35    fprintf(stderr, "waitpid(): no completed child found\n");
36  } else if (child < 0) {
37    fprintf(stderr, "waitpid(): failed errno=%d %s\n", errno, strerror(errno));
38  } else {
39    fprintf(stderr, "waitpid(): found completed child %ld\n", (long)child);
40  }
41  return 0;
42}
43