source: asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/misc/forkpty.c@ 337

#include <pty.h>
#include <utmp.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <pthread.h>

int forkpty(int *pm, char *name, const struct termios *tio, const struct winsize *ws)
{
        int m, s, ec=0, p[2], cs;
        pid_t pid=-1;
        sigset_t set, oldset;

        if (openpty(&m, &s, name, tio, ws) < 0) return -1;

        sigfillset(&set);
        pthread_sigmask(SIG_BLOCK, &set, &oldset);
        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);

        if (pipe2(p, O_CLOEXEC)) {
                close(s);
                goto out;
        }

        pid = fork();
        if (!pid) {
                close(m);
                close(p[0]);
                if (login_tty(s)) {
                        write(p[1], &errno, sizeof errno);
                        _exit(127);
                }
                close(p[1]);
                pthread_setcancelstate(cs, 0);
                pthread_sigmask(SIG_SETMASK, &oldset, 0);
                return 0;
        }
        close(s);
        close(p[1]);
        if (read(p[0], &ec, sizeof ec) > 0) {
                int status;
                waitpid(pid, &status, 0);
                pid = -1;
                errno = ec;
        }
        close(p[0]);

out:
        if (pid > 0) *pm = m;
        else close(m);

        pthread_setcancelstate(cs, 0);
        pthread_sigmask(SIG_SETMASK, &oldset, 0);

        return pid;
}