waitfor.c

/* Copyright (c) 2019-2021, Michael Santos <michael.santos@gmail.com>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include <errno.h>
#include <signal.h>

#ifdef RESTRICT_PROCESS_capsicum
#include <stdlib.h>
#include <sys/event.h>
#endif

#include "waitfor.h"

int waitfor(int fdp, int *status) {
#ifdef RESTRICT_PROCESS_capsicum
  struct kevent event;
  int kq;
  int rv;

  kq = kqueue();
  if (kq == -1)
    return -1;

  EV_SET(&event, fdp, EVFILT_PROCDESC, EV_ADD | EV_CLEAR | EV_ONESHOT,
         NOTE_EXIT, 0, NULL);

  rv = kevent(kq, &event, 1, &event, 1, NULL);
  if (rv == -1) {
    switch (errno) {
    case EINTR:
      return 0;
    default:
      return -1;
    }
  }

  *status = (int)event.data;
  return 0;
#else
  (void)fdp;
  for (;;) {
    errno = 0;
    if (wait(status) < 0) {
      if (errno == EINTR)
        continue;
      return -1;
    }
    return 0;
  }
#endif
}