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In del_io_events(), avoid reading from the pty master in blocking

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mode.  We now do two passes, one with SUDO_EVLOOP_NONBLOCK and
another that could block if stdin is a pipe.  This ensures we consume
the pipe until EOF.
This commit is contained in:
Todd C. Miller
2016-05-20 10:17:23 -06:00
parent 223b251c19
commit 8f694cc228
1 changed files with 40 additions and 7 deletions
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47
src/exec_pty.c
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@@ -90,7 +90,7 @@ static pid_t ppgrp, cmnd_pgrp, mon_pgrp;
static sigset_t ttyblock;
static struct io_buffer_list iobufs;
static void del_io_events(int flags);
static void del_io_events(bool nonblocking);
static int exec_monitor(struct command_details *details, int backchannel);
static void exec_pty(struct command_details *details,
struct command_status *cstat, int errfd);
@@ -189,6 +189,9 @@ pty_setup(uid_t uid, const char *tty, const char *utmp_user)
/* Add entry to utmp/utmpx? */
if (utmp_user != NULL)
utmp_login(tty, slavename, io_fds[SFD_SLAVE], utmp_user);
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: /dev/tty fd %d, pty master fd %d, pty slave fd %d", __func__,
io_fds[SFD_USERTTY], io_fds[SFD_MASTER], io_fds[SFD_SLAVE]);
}
debug_return;
@@ -447,7 +450,7 @@ suspend_parent(int signo)
case SIGSTOP:
case SIGTSTP:
/* Flush any remaining output and deschedule I/O events. */
del_io_events(SUDO_EVLOOP_NONBLOCK);
del_io_events(true);
/* Restore original tty mode before suspending. */
if (ttymode != TERM_COOKED)
@@ -893,7 +896,7 @@ pty_close(struct command_status *cstat)
(void) fcntl(io_fds[SFD_USERTTY], F_SETFL, n);
}
}
del_io_events(SUDO_EVLOOP_ONCE);
del_io_events(false);
/* Free I/O buffers. */
while ((iob = SLIST_FIRST(&iobufs)) != NULL) {
@@ -974,7 +977,7 @@ add_io_events(struct sudo_event_base *evbase)
* than /dev/tty. Removes I/O events from the event base when done.
*/
static void
del_io_events(int flags)
del_io_events(bool nonblocking)
{
struct io_buffer *iob;
struct sudo_event_base *evbase;
@@ -1018,11 +1021,41 @@ del_io_events(int flags)
}
}
}
(void) sudo_ev_loop(evbase, SUDO_EVLOOP_NONBLOCK);
(void) sudo_ev_loop(evbase, flags);
/*
* If not in non-blocking mode, make sure we flush pipes completely.
* We don't want to read from the pty since that might block and
* the command is no longer running anyway.
*/
if (!nonblocking) {
/* Clear out iobufs from event base. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->revent != NULL && !USERTTY_EVENT(iob->revent))
sudo_ev_del(evbase, iob->revent);
if (iob->wevent != NULL)
sudo_ev_del(evbase, iob->wevent);
}
if (!ISSET(flags, SUDO_EVLOOP_NONBLOCK)) {
/* In blocking mode we should have flushed all buffers. */
SLIST_FOREACH(iob, &iobufs, entries) {
/* Only flush from stdin (pipe). */
if (iob->revent != NULL && sudo_ev_get_fd(iob->revent) == SFD_STDIN) {
if (iob->len != sizeof(iob->buf)) {
if (sudo_ev_add(evbase, iob->revent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
/* Flush any write buffers with data in them. */
if (iob->wevent != NULL) {
if (iob->len > iob->off) {
if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
sudo_fatal(U_("unable to add event to queue"));
}
}
}
(void) sudo_ev_loop(evbase, 0);
/* We should now have flushed all buffers. */
SLIST_FOREACH(iob, &iobufs, entries) {
if (iob->wevent != NULL) {
if (iob->len > iob->off) {