macOS program to get current working directory of any PID.

cwd.c

#include <errno.h>
#include <libproc.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

// Works on macOS using libproc.

int main(int argc, char *argv[]) {
  int ret;
  pid_t pid;
  struct proc_vnodepathinfo vpi;

  if (argc == 2) {
    pid = (pid_t)atoi(argv[1]);
    ret = proc_pidinfo(pid, PROC_PIDVNODEPATHINFO, 0, &vpi,
                       PROC_PIDVNODEPATHINFO_SIZE);
    if (ret <= 0) {
      fprintf(stderr, "%s\n", strerror(errno));
      return 1;
    }
    printf("%s\n", vpi.pvi_cdir.vip_path);
  } else {
    printf("Usage: %s <pid>\n\n", argv[0]);
    printf("Print the current working directory for <pid> to stdout.\n");
  }

  return 0;
}