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;
}
ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
uint8_t *p = buf;
ssize_t n = 0;
assert(fd >= 0);
assert(buf);
/* If called with nbytes == 0, let's call read() at least
* once, to validate the operation */
if (nbytes > (size_t) SSIZE_MAX)
return -EINVAL;
do {
ssize_t k;
k = read(fd, p, nbytes);
if (k < 0) {
if (errno == EINTR)
continue;
if (errno == EAGAIN && do_poll) {
/* We knowingly ignore any return value here,
* and expect that any error/EOF is reported
* via read() */
(void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
continue;
}
return n > 0 ? n : -errno;
}
if (k == 0)
return n;
assert((size_t) k <= nbytes);
p += k;
nbytes -= k;
n += k;
} while (nbytes > 0);
return n;
}
int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
const uint8_t *p = buf;
assert(fd >= 0);
assert(buf);
if (nbytes > (size_t) SSIZE_MAX)
return -EINVAL;
do {
ssize_t k;
k = write(fd, p, nbytes);
if (k < 0) {
if (errno == EINTR)
continue;
if (errno == EAGAIN && do_poll) {
/* We knowingly ignore any return value here,
* and expect that any error/EOF is reported
* via write() */
(void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
continue;
}
return -errno;
}
if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */
return -EIO;
assert((size_t) k <= nbytes);
p += k;
nbytes -= k;
} while (nbytes > 0);
return 0;
}
int polkit_agent_open(void) {
int r;
int pipe_fd[2];
char notify_fd[DECIMAL_STR_MAX(int) + 1];
if (agent_pid > 0)
return 0;
/* We check STDIN here, not STDOUT, since this is about input,
* not output */
if (!isatty(STDIN_FILENO))
return 0;
if (pipe2(pipe_fd, 0) < 0)
return -errno;
xsprintf(notify_fd, "%i", pipe_fd[1]);
r = fork_agent(&agent_pid,
&pipe_fd[1], 1,
POLKIT_AGENT_BINARY_PATH,
POLKIT_AGENT_BINARY_PATH, "--notify-fd", notify_fd, "--fallback", NULL);
/* Close the writing side, because that's the one for the agent */
safe_close(pipe_fd[1]);
if (r < 0)
log_error_errno(r, "Failed to fork TTY ask password agent: %m");
else
/* Wait until the agent closes the fd */
fd_wait_for_event(pipe_fd[0], POLLHUP, USEC_INFINITY);
safe_close(pipe_fd[0]);
return r;
}
int acquire_terminal(
const char *name,
bool fail,
bool force,
bool ignore_tiocstty_eperm,
usec_t timeout) {
int fd = -1, notify = -1, r = 0, wd = -1;
usec_t ts = 0;
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 (timeout != USEC_INFINITY)
ts = now(CLOCK_MONOTONIC);
if (!fail && !force) {
notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
if (notify < 0) {
r = -errno;
goto fail;
}
wd = inotify_add_watch(notify, name, IN_CLOSE);
if (wd < 0) {
r = -errno;
goto fail;
}
}
for (;;) {
struct sigaction sa_old, sa_new = {
.sa_handler = SIG_IGN,
.sa_flags = SA_RESTART,
};
if (notify >= 0) {
r = flush_fd(notify);
if (r < 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 */
fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return fd;
/* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
* if we already own the tty. */
assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
/* First, try to get the tty */
if (ioctl(fd, TIOCSCTTY, force) < 0)
r = -errno;
assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
/* Sometimes it makes sense to ignore TIOCSCTTY
* returning EPERM, i.e. when very likely we already
* are have this controlling terminal. */
if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
r = 0;
if (r < 0 && (force || fail || r != -EPERM))
goto fail;
if (r >= 0)
break;
assert(!fail);
assert(!force);
assert(notify >= 0);
for (;;) {
union inotify_event_buffer buffer;
struct inotify_event *e;
ssize_t l;
if (timeout != USEC_INFINITY) {
usec_t n;
n = now(CLOCK_MONOTONIC);
if (ts + timeout < n) {
r = -ETIMEDOUT;
goto fail;
}
r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
if (r < 0)
goto fail;
if (r == 0) {
r = -ETIMEDOUT;
goto fail;
}
}
l = read(notify, &buffer, sizeof(buffer));
if (l < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
r = -errno;
goto fail;
}
FOREACH_INOTIFY_EVENT(e, buffer, l) {
if (e->wd != wd || !(e->mask & IN_CLOSE)) {
r = -EIO;
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. */
fd = safe_close(fd);
}
safe_close(notify);
r = reset_terminal_fd(fd, true);
if (r < 0)
log_warning_errno(r, "Failed to reset terminal: %m");
return fd;
fail:
safe_close(fd);
safe_close(notify);
return r;
}