1#include <pty.h>
2#include <utmp.h>
3#include <unistd.h>
4#include <errno.h>
5#include <fcntl.h>
6#include <sys/wait.h>
7#include <pthread.h>
8
9int forkpty(int *pm, char *name, const struct termios *tio, const struct winsize *ws)
10{
11	int m, s, ec=0, p[2], cs;
12	pid_t pid=-1;
13	sigset_t set, oldset;
14
15	if (openpty(&m, &s, name, tio, ws) < 0) return -1;
16
17	sigfillset(&set);
18	pthread_sigmask(SIG_BLOCK, &set, &oldset);
19	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
20
21	if (pipe2(p, O_CLOEXEC)) {
22		close(s);
23		goto out;
24	}
25
26	pid = fork();
27	if (!pid) {
28		close(m);
29		close(p[0]);
30		if (login_tty(s)) {
31			write(p[1], &errno, sizeof errno);
32			_exit(127);
33		}
34		close(p[1]);
35		pthread_setcancelstate(cs, 0);
36		pthread_sigmask(SIG_SETMASK, &oldset, 0);
37		return 0;
38	}
39	close(s);
40	close(p[1]);
41	if (read(p[0], &ec, sizeof ec) > 0) {
42		int status;
43		waitpid(pid, &status, 0);
44		pid = -1;
45		errno = ec;
46	}
47	close(p[0]);
48
49out:
50	if (pid > 0) *pm = m;
51	else close(m);
52
53	pthread_setcancelstate(cs, 0);
54	pthread_sigmask(SIG_SETMASK, &oldset, 0);
55
56	return pid;
57}
58