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/* $OpenBSD: kqueue-process.c,v 1.9 2016/03/17 19:40:43 krw Exp $ */
/*
* Written by Artur Grabowski <art@openbsd.org> 2002 Public Domain
*/
#include <sys/types.h>
#include <sys/event.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <stdio.h>
#include <err.h>
#include <unistd.h>
#include <signal.h>
static int process_child(void);
#define ASS(cond, mess) do { if (!(cond)) { mess; return 1; } } while (0)
#define ASSX(cond) ASS(cond, warnx("assertion " #cond " failed on line %d", __LINE__))
static void
usr1handler(int signum)
{
/* nada */
}
int do_process(void);
int
do_process(void)
{
struct kevent ke;
int kq, status;
pid_t pid, pid2;
int didfork, didchild;
int i;
struct timespec ts;
/*
* Timeout in case something doesn't work.
*/
ts.tv_sec = 10;
ts.tv_nsec = 0;
ASS((kq = kqueue()) >= 0, warn("kqueue"));
/*
* Install a signal handler so that we can use pause() to synchronize
* with the child with the parent.
*/
signal(SIGUSR1, usr1handler);
switch ((pid = fork())) {
case -1:
err(1, "fork");
case 0:
_exit(process_child());
}
sleep(2); /* wait for child to settle down. */
EV_SET(&ke, pid, EVFILT_PROC, EV_ADD|EV_ENABLE|EV_CLEAR,
NOTE_EXIT|NOTE_FORK|NOTE_EXEC|NOTE_TRACK, 0, NULL);
ASS(kevent(kq, &ke, 1, NULL, 0, NULL) == 0,
warn("can't register events on kqueue"));
kill(pid, SIGUSR1); /* sync 1 */
didfork = didchild = 0;
pid2 = -1;
for (i = 0; i < 2; i++) {
ASS(kevent(kq, NULL, 0, &ke, 1, &ts) == 1,
warnx("didn't receive event"));
ASSX(ke.filter == EVFILT_PROC);
switch (ke.fflags) {
case NOTE_CHILD:
didchild = 1;
ASSX((pid_t)ke.data == pid);
pid2 = ke.ident;
fprintf(stderr, "child %d (from %d)\n", pid2, pid);
break;
case NOTE_FORK:
didfork = 1;
ASSX(ke.ident == pid);
fprintf(stderr, "fork\n");
break;
case NOTE_TRACKERR:
errx(1, "child tracking failed due to resource shortage");
default:
errx(1, "kevent returned weird event 0x%x pid %d",
ke.fflags, (pid_t)ke.ident);
}
}
if (pid2 == -1)
return (1);
/* Both children now sleeping. */
ASSX(didchild == 1);
ASSX(didfork == 1);
kill(pid2, SIGUSR1); /* sync 2.1 */
kill(pid, SIGUSR1); /* sync 2 */
/* Wait for child's exit. */
if (wait(&status) < 0)
err(1, "wait");
/* Wait for child-child's exec/exit to receive two events at once. */
sleep(1);
for (i = 0; i < 2; i++) {
ASS(kevent(kq, NULL, 0, &ke, 1, &ts) == 1,
warnx("didn't receive event"));
ASSX(ke.filter == EVFILT_PROC);
switch (ke.fflags) {
case NOTE_EXIT:
ASSX((pid_t)ke.ident == pid);
fprintf(stderr, "child exit %d\n", pid);
break;
case NOTE_EXEC | NOTE_EXIT:
ASSX((pid_t)ke.ident == pid2);
fprintf(stderr, "child-child exec/exit %d\n", pid2);
break;
default:
errx(1, "kevent returned weird event 0x%x pid %d",
ke.fflags, (pid_t)ke.ident);
}
}
if (!WIFEXITED(status))
errx(1, "child didn't exit?");
close(kq);
return (WEXITSTATUS(status) != 0);
}
static int
process_child(void)
{
signal(SIGCHLD, SIG_IGN); /* ignore our children. */
pause();
/* fork and see if tracking works. */
switch (fork()) {
case -1:
err(1, "fork");
case 0:
/* sync 2.1 */
pause();
execl("/usr/bin/true", "true", (char *)NULL);
err(1, "execl(true)");
}
/* sync 2 */
pause();
return 0;
}
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