+int open_terminal(const char *name, int mode) {
+ int fd, r;
+
+ if ((fd = open(name, mode)) < 0)
+ return -errno;
+
+ if ((r = isatty(fd)) < 0) {
+ close_nointr_nofail(fd);
+ return -errno;
+ }
+
+ if (!r) {
+ close_nointr_nofail(fd);
+ return -ENOTTY;
+ }
+
+ return fd;
+}
+
+int flush_fd(int fd) {
+ struct pollfd pollfd;
+
+ zero(pollfd);
+ pollfd.fd = fd;
+ pollfd.events = POLLIN;
+
+ for (;;) {
+ char buf[1024];
+ ssize_t l;
+ int r;
+
+ if ((r = poll(&pollfd, 1, 0)) < 0) {
+
+ if (errno == EINTR)
+ continue;
+
+ return -errno;
+ }
+
+ if (r == 0)
+ return 0;
+
+ if ((l = read(fd, buf, sizeof(buf))) < 0) {
+
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN)
+ return 0;
+
+ return -errno;
+ }
+
+ if (l <= 0)
+ return 0;
+ }
+}
+
+int acquire_terminal(const char *name, bool fail, bool force) {
+ int fd = -1, notify = -1, r, wd;
+
+ assert(name);
+
+ /* We use inotify to be notified when the tty is closed. We
+ * create the watch before checking if we can actually acquire
+ * it, so that we don't lose any event.
+ *
+ * Note: strictly speaking this actually watches for the
+ * device being closed, it does *not* really watch whether a
+ * tty loses its controlling process. However, unless some
+ * rogue process uses TIOCNOTTY on /dev/tty *after* closing
+ * its tty otherwise this will not become a problem. As long
+ * as the administrator makes sure not configure any service
+ * on the same tty as an untrusted user this should not be a
+ * problem. (Which he probably should not do anyway.) */
+
+ if (!fail && !force) {
+ if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ if ((wd = inotify_add_watch(notify, name, IN_CLOSE)) < 0) {
+ r = -errno;
+ goto fail;
+ }
+ }
+
+ for (;;) {
+ if ((r = flush_fd(notify)) < 0)
+ goto fail;
+
+ /* We pass here O_NOCTTY only so that we can check the return
+ * value TIOCSCTTY and have a reliable way to figure out if we
+ * successfully became the controlling process of the tty */
+ if ((fd = open_terminal(name, O_RDWR|O_NOCTTY)) < 0)
+ return -errno;
+
+ /* First, try to get the tty */
+ if ((r = ioctl(fd, TIOCSCTTY, force)) < 0 &&
+ (force || fail || errno != EPERM)) {
+ r = -errno;
+ goto fail;
+ }
+
+ if (r >= 0)
+ break;
+
+ assert(!fail);
+ assert(!force);
+ assert(notify >= 0);
+
+ for (;;) {
+ struct inotify_event e;
+ ssize_t l;
+
+ if ((l = read(notify, &e, sizeof(e))) != sizeof(e)) {
+
+ if (l < 0) {
+
+ if (errno == EINTR)
+ continue;
+
+ r = -errno;
+ } else
+ r = -EIO;
+
+ goto fail;
+ }
+
+ if (e.wd != wd || !(e.mask & IN_CLOSE)) {
+ r = -errno;
+ goto fail;
+ }
+
+ break;
+ }
+
+ /* We close the tty fd here since if the old session
+ * ended our handle will be dead. It's important that
+ * we do this after sleeping, so that we don't enter
+ * an endless loop. */
+ close_nointr_nofail(fd);
+ }
+
+ if (notify >= 0)
+ close_nointr_nofail(notify);
+
+ if ((r = reset_terminal(fd)) < 0)
+ log_warning("Failed to reset terminal: %s", strerror(-r));
+
+ return fd;
+
+fail:
+ if (fd >= 0)
+ close_nointr_nofail(fd);
+
+ if (notify >= 0)
+ close_nointr_nofail(notify);
+
+ return r;
+}
+
+int release_terminal(void) {
+ int r = 0, fd;
+ struct sigaction sa_old, sa_new;
+
+ if ((fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_NDELAY)) < 0)
+ return -errno;
+
+ /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
+ * by our own TIOCNOTTY */
+
+ zero(sa_new);
+ sa_new.sa_handler = SIG_IGN;
+ sa_new.sa_flags = SA_RESTART;
+ assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
+
+ if (ioctl(fd, TIOCNOTTY) < 0)
+ r = -errno;
+
+ assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
+
+ close_nointr_nofail(fd);
+ return r;
+}
+
+int ignore_signal(int sig) {
+ struct sigaction sa;
+
+ zero(sa);
+ sa.sa_handler = SIG_IGN;
+ sa.sa_flags = SA_RESTART;
+
+ return sigaction(sig, &sa, NULL);
+}
+
+int close_pipe(int p[]) {
+ int a = 0, b = 0;
+
+ assert(p);
+
+ if (p[0] >= 0) {
+ a = close_nointr(p[0]);
+ p[0] = -1;
+ }
+
+ if (p[1] >= 0) {
+ b = close_nointr(p[1]);
+ p[1] = -1;
+ }
+
+ return a < 0 ? a : b;
+}
+
+ssize_t loop_read(int fd, void *buf, size_t nbytes) {
+ uint8_t *p;
+ ssize_t n = 0;
+
+ assert(fd >= 0);
+ assert(buf);
+
+ p = buf;
+
+ while (nbytes > 0) {
+ ssize_t k;
+
+ if ((k = read(fd, p, nbytes)) <= 0) {
+
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN) {
+ struct pollfd pollfd;
+
+ zero(pollfd);
+ pollfd.fd = fd;
+ pollfd.events = POLLIN;
+
+ if (poll(&pollfd, 1, -1) < 0) {
+ if (errno == EINTR)
+ continue;
+
+ return n > 0 ? n : -errno;
+ }
+
+ if (pollfd.revents != POLLIN)
+ return n > 0 ? n : -EIO;
+
+ continue;
+ }
+
+ return n > 0 ? n : (k < 0 ? -errno : 0);
+ }
+
+ p += k;
+ nbytes -= k;
+ n += k;
+ }
+
+ return n;
+}
+
+int path_is_mount_point(const char *t) {
+ struct stat a, b;
+ char *copy;
+
+ if (lstat(t, &a) < 0) {
+
+ if (errno == ENOENT)
+ return 0;
+
+ return -errno;
+ }
+
+ if (!(copy = strdup(t)))
+ return -ENOMEM;
+
+ if (lstat(dirname(copy), &b) < 0) {
+ free(copy);
+ return -errno;
+ }
+
+ free(copy);
+
+ return a.st_dev != b.st_dev;
+}
+
+int parse_usec(const char *t, usec_t *usec) {
+ static const struct {
+ const char *suffix;
+ usec_t usec;
+ } table[] = {
+ { "sec", USEC_PER_SEC },
+ { "s", USEC_PER_SEC },
+ { "min", USEC_PER_MINUTE },
+ { "hr", USEC_PER_HOUR },
+ { "h", USEC_PER_HOUR },
+ { "d", USEC_PER_DAY },
+ { "w", USEC_PER_WEEK },
+ { "msec", USEC_PER_MSEC },
+ { "ms", USEC_PER_MSEC },
+ { "m", USEC_PER_MINUTE },
+ { "usec", 1ULL },
+ { "us", 1ULL },
+ { "", USEC_PER_SEC },
+ };
+
+ const char *p;
+ usec_t r = 0;
+
+ assert(t);
+ assert(usec);
+
+ p = t;
+ do {
+ long long l;
+ char *e;
+ unsigned i;
+
+ errno = 0;
+ l = strtoll(p, &e, 10);
+
+ if (errno != 0)
+ return -errno;
+
+ if (l < 0)
+ return -ERANGE;
+
+ if (e == p)
+ return -EINVAL;
+
+ e += strspn(e, WHITESPACE);
+
+ for (i = 0; i < ELEMENTSOF(table); i++)
+ if (startswith(e, table[i].suffix)) {
+ r += (usec_t) l * table[i].usec;
+ p = e + strlen(table[i].suffix);
+ break;
+ }
+
+ if (i >= ELEMENTSOF(table))
+ return -EINVAL;
+
+ } while (*p != 0);
+
+ *usec = r;
+
+ return 0;
+}
+