We don't need to be the foreground process to be able to write to

the terminal in most cases.  If the background process tries to
modify the terminal flags it will receive SIGTTOU which is relayed
to the sudo front-end.  This currently mishandles terminals with
the TOSTOP local flag set.

diff --git a/src/exec_pty.c b/src/exec_pty.c
index f55506655db0f1ff54a0751c715d868126903ba7..65caf2f6a5527288827043e9f65ba55088fcf8ea 100644 (file)
--- a/src/exec_pty.c
+++ b/src/exec_pty.c
@@ -563,9 +563,8 @@ read_callback(int fd, int what, void *v)
                iob->ec->cmnd_pid = -1;
            }
            iob->len += n;
-           /* Enable writer if not /dev/tty or we are foreground pgrp. */
-           if (iob->wevent != NULL &&
-               (foreground || !USERTTY_EVENT(iob->wevent))) {
+           /* Enable writer now that there is data in the buffer. */
+           if (iob->wevent != NULL) {
                if (sudo_ev_add(evbase, iob->wevent, NULL, false) == -1)
                    sudo_fatal(U_("unable to add event to queue"));
            }
@@ -1452,7 +1451,7 @@ add_io_events(struct sudo_event_base *evbase)
      * Normally, write buffers are added on demand when data is read.
      */
     SLIST_FOREACH(iob, &iobufs, entries) {
-       /* Don't read/write from /dev/tty if we are not in the foreground. */
+       /* Don't read from /dev/tty if we are not in the foreground. */
        if (iob->revent != NULL &&
            (ttymode == TERM_RAW || !USERTTY_EVENT(iob->revent))) {
            if (iob->len != sizeof(iob->buf)) {
@@ -1463,8 +1462,8 @@ add_io_events(struct sudo_event_base *evbase)
                    sudo_fatal(U_("unable to add event to queue"));
            }
        }
-       if (iob->wevent != NULL &&
-           (foreground || !USERTTY_EVENT(iob->wevent))) {
+       if (iob->wevent != NULL) {
+           /* Enable writer if buffer is not empty. */
            if (iob->len > iob->off) {
                sudo_debug_printf(SUDO_DEBUG_INFO,
                    "added I/O wevent %p, fd %d, events %d",