+int chvt(int vt) {
+ _cleanup_close_ int fd;
+
+ fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ if (vt < 0) {
+ int tiocl[2] = {
+ TIOCL_GETKMSGREDIRECT,
+ 0
+ };
+
+ if (ioctl(fd, TIOCLINUX, tiocl) < 0)
+ return -errno;
+
+ vt = tiocl[0] <= 0 ? 1 : tiocl[0];
+ }
+
+ if (ioctl(fd, VT_ACTIVATE, vt) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
+ struct termios old_termios, new_termios;
+ char c, line[LINE_MAX];
+
+ assert(f);
+ assert(ret);
+
+ if (tcgetattr(fileno(f), &old_termios) >= 0) {
+ new_termios = old_termios;
+
+ new_termios.c_lflag &= ~ICANON;
+ new_termios.c_cc[VMIN] = 1;
+ new_termios.c_cc[VTIME] = 0;
+
+ if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
+ size_t k;
+
+ if (t != USEC_INFINITY) {
+ if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
+ tcsetattr(fileno(f), TCSADRAIN, &old_termios);
+ return -ETIMEDOUT;
+ }
+ }
+
+ k = fread(&c, 1, 1, f);
+
+ tcsetattr(fileno(f), TCSADRAIN, &old_termios);
+
+ if (k <= 0)
+ return -EIO;
+
+ if (need_nl)
+ *need_nl = c != '\n';
+
+ *ret = c;
+ return 0;
+ }
+ }
+
+ if (t != USEC_INFINITY) {
+ if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
+ return -ETIMEDOUT;
+ }
+
+ errno = 0;
+ if (!fgets(line, sizeof(line), f))
+ return errno ? -errno : -EIO;
+
+ truncate_nl(line);
+
+ if (strlen(line) != 1)
+ return -EBADMSG;
+
+ if (need_nl)
+ *need_nl = false;
+
+ *ret = line[0];
+ return 0;
+}
+
+int ask_char(char *ret, const char *replies, const char *text, ...) {
+ int r;
+
+ assert(ret);
+ assert(replies);
+ assert(text);
+
+ for (;;) {
+ va_list ap;
+ char c;
+ bool need_nl = true;
+
+ if (on_tty())
+ fputs(ANSI_HIGHLIGHT_ON, stdout);
+
+ va_start(ap, text);
+ vprintf(text, ap);
+ va_end(ap);
+
+ if (on_tty())
+ fputs(ANSI_HIGHLIGHT_OFF, stdout);
+
+ fflush(stdout);
+
+ r = read_one_char(stdin, &c, USEC_INFINITY, &need_nl);
+ if (r < 0) {
+
+ if (r == -EBADMSG) {
+ puts("Bad input, please try again.");
+ continue;
+ }
+
+ putchar('\n');
+ return r;
+ }
+
+ if (need_nl)
+ putchar('\n');
+
+ if (strchr(replies, c)) {
+ *ret = c;
+ return 0;
+ }
+
+ puts("Read unexpected character, please try again.");
+ }
+}
+
+int ask_string(char **ret, const char *text, ...) {
+ assert(ret);
+ assert(text);
+
+ for (;;) {
+ char line[LINE_MAX];
+ va_list ap;
+
+ if (on_tty())
+ fputs(ANSI_HIGHLIGHT_ON, stdout);
+
+ va_start(ap, text);
+ vprintf(text, ap);
+ va_end(ap);
+
+ if (on_tty())
+ fputs(ANSI_HIGHLIGHT_OFF, stdout);
+
+ fflush(stdout);
+
+ errno = 0;
+ if (!fgets(line, sizeof(line), stdin))
+ return errno ? -errno : -EIO;
+
+ if (!endswith(line, "\n"))
+ putchar('\n');
+ else {
+ char *s;
+
+ if (isempty(line))
+ continue;
+
+ truncate_nl(line);
+ s = strdup(line);
+ if (!s)
+ return -ENOMEM;
+
+ *ret = s;
+ return 0;
+ }
+ }
+}
+
+int reset_terminal_fd(int fd, bool switch_to_text) {
+ struct termios termios;
+ int r = 0;
+
+ /* Set terminal to some sane defaults */
+
+ assert(fd >= 0);
+
+ /* We leave locked terminal attributes untouched, so that
+ * Plymouth may set whatever it wants to set, and we don't
+ * interfere with that. */
+
+ /* Disable exclusive mode, just in case */
+ ioctl(fd, TIOCNXCL);
+
+ /* Switch to text mode */
+ if (switch_to_text)
+ ioctl(fd, KDSETMODE, KD_TEXT);
+
+ /* Enable console unicode mode */
+ ioctl(fd, KDSKBMODE, K_UNICODE);
+
+ if (tcgetattr(fd, &termios) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ /* We only reset the stuff that matters to the software. How
+ * hardware is set up we don't touch assuming that somebody
+ * else will do that for us */
+
+ termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
+ termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
+ termios.c_oflag |= ONLCR;
+ termios.c_cflag |= CREAD;
+ termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
+
+ termios.c_cc[VINTR] = 03; /* ^C */
+ termios.c_cc[VQUIT] = 034; /* ^\ */
+ termios.c_cc[VERASE] = 0177;
+ termios.c_cc[VKILL] = 025; /* ^X */
+ termios.c_cc[VEOF] = 04; /* ^D */
+ termios.c_cc[VSTART] = 021; /* ^Q */
+ termios.c_cc[VSTOP] = 023; /* ^S */
+ termios.c_cc[VSUSP] = 032; /* ^Z */
+ termios.c_cc[VLNEXT] = 026; /* ^V */
+ termios.c_cc[VWERASE] = 027; /* ^W */
+ termios.c_cc[VREPRINT] = 022; /* ^R */
+ termios.c_cc[VEOL] = 0;
+ termios.c_cc[VEOL2] = 0;
+
+ termios.c_cc[VTIME] = 0;
+ termios.c_cc[VMIN] = 1;
+
+ if (tcsetattr(fd, TCSANOW, &termios) < 0)
+ r = -errno;
+
+finish:
+ /* Just in case, flush all crap out */
+ tcflush(fd, TCIOFLUSH);
+
+ return r;
+}
+
+int reset_terminal(const char *name) {
+ _cleanup_close_ int fd = -1;
+
+ fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
+ if (fd < 0)
+ return fd;
+
+ return reset_terminal_fd(fd, true);
+}
+
+int open_terminal(const char *name, int mode) {
+ int fd, r;
+ unsigned c = 0;
+
+ /*
+ * If a TTY is in the process of being closed opening it might
+ * cause EIO. This is horribly awful, but unlikely to be
+ * changed in the kernel. Hence we work around this problem by
+ * retrying a couple of times.
+ *
+ * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
+ */
+
+ assert(!(mode & O_CREAT));
+
+ for (;;) {
+ fd = open(name, mode, 0);
+ if (fd >= 0)
+ break;
+
+ if (errno != EIO)
+ return -errno;
+
+ /* Max 1s in total */
+ if (c >= 20)
+ return -errno;
+
+ usleep(50 * USEC_PER_MSEC);
+ c++;
+ }
+
+ r = isatty(fd);
+ if (r < 0) {
+ safe_close(fd);
+ return -errno;
+ }
+
+ if (!r) {
+ safe_close(fd);
+ return -ENOTTY;
+ }
+
+ return fd;
+}
+