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On resume, always sync the pty terminal settings with /dev/tty.

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Changes made to the terminal settings while the command is suspended
are now reflected in the pty when the command is resumed.  This is
more consistent with the non-pty behavior and allows for the removal
of the "tty_initialized" global.  One downside to this change is
that if a terminal-based program using the pty is stopped with
SIGSTOP it may have the wrong terminal settings on resume.
However, this is no different from the non-pty case.
This commit is contained in:
Todd C. Miller
2023-03-23 10:39:28 -06:00
parent 3e734fa51b
commit 51cdb194b8
1 changed files with 27 additions and 25 deletions
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52
src/exec_pty.c
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@@ -59,7 +59,6 @@ static struct monitor_message_list monitor_messages =
static char ptyname[PATH_MAX];
static bool foreground, pipeline;
static bool tty_initialized;
static const char *utmp_user;
static void sync_ttysize(struct exec_closure *ec);
@@ -160,14 +159,6 @@ check_foreground(struct exec_closure *ec)
if (io_fds[SFD_USERTTY] != -1) {
if ((ret = tcgetpgrp(io_fds[SFD_USERTTY])) != -1) {
foreground = ret == ec->ppgrp;
if (foreground && !tty_initialized) {
/* Re-initialize the pty if needed. */
if (sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER]))
tty_initialized = true;
}
/* Also check for window size changes. */
sync_ttysize(ec);
}
}
debug_return_int(ret);
@@ -186,14 +177,14 @@ resume_terminal(struct exec_closure *ec)
debug_return_bool(false);
}
/*
* We always resume the command in the foreground if sudo itself
* is the foreground process. This helps work around poorly behaved
* programs that catch SIGTTOU/SIGTTIN but suspend themselves with
* SIGSTOP. At worst, sudo will go into the background but upon
* resume the command will be runnable. Otherwise, we can get into
* a situation where the command will immediately suspend itself.
*/
/* Update the pty settings based on the user's terminal. */
if (!sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_LEADER])) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: unable to copy terminal settings to pty", __func__);
debug_return_bool(false);
}
sync_ttysize(ec);
sudo_debug_printf(SUDO_DEBUG_INFO, "parent is in %s, ttymode %d -> %d",
foreground ? "foreground" : "background", ttymode,
foreground ? TERM_RAW : TERM_COOKED);
@@ -234,6 +225,9 @@ suspend_sudo_pty(struct exec_closure *ec, int signo)
if (sudo_sigaction(SIGCONT, &sa, &saved_sigcont) != 0)
sudo_warn(U_("unable to set handler for SIGCONT"));
if (sig2str(signo, signame) == -1)
(void)snprintf(signame, sizeof(signame), "%d", signo);
switch (signo) {
case SIGTTOU:
case SIGTTIN:
@@ -248,6 +242,9 @@ suspend_sudo_pty(struct exec_closure *ec, int signo)
}
}
if (foreground) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"%s: command received SIG%s, parent running in the foregound",
__func__, signame);
if (ttymode != TERM_RAW) {
if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
ttymode = TERM_RAW;
@@ -271,9 +268,6 @@ suspend_sudo_pty(struct exec_closure *ec, int signo)
/* Log the suspend event. */
log_suspend(ec, signo);
if (sig2str(signo, signame) == -1)
(void)snprintf(signame, sizeof(signame), "%d", signo);
/* Suspend self and continue command when we resume. */
if (signo != SIGSTOP) {
if (sudo_sigaction(signo, &sa, &osa) != 0)
@@ -289,12 +283,12 @@ suspend_sudo_pty(struct exec_closure *ec, int signo)
* If the process group leader is no longer present, we must kill
* the command since there will be no one to resume us.
*/
sudo_debug_printf(SUDO_DEBUG_INFO, "killpg(%d, SIG%s) [parent]",
(int)ec->ppgrp, signame);
sudo_debug_printf(SUDO_DEBUG_INFO, "%s: killpg(%d, SIG%s) [parent]",
__func__, (int)ec->ppgrp, signame);
if ((ec->ppgrp != ec->sudo_pid && kill(ec->ppgrp, 0) == -1) ||
killpg(ec->ppgrp, signo) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR,
"no parent to suspend, terminating command.");
"%s: no parent to suspend, terminating command.", __func__);
terminate_command(ec->cmnd_pid, true);
ec->cmnd_pid = -1;
}
@@ -311,10 +305,19 @@ suspend_sudo_pty(struct exec_closure *ec, int signo)
/* Log the resume event. */
log_suspend(ec, SIGCONT);
/* Restore the user's terminal settings. */
/* Update the pty's terminal settings and restore /dev/tty settings. */
if (!resume_terminal(ec))
break;
/*
* We always resume the command in the foreground if sudo itself
* is the foreground process (and we were able to set /dev/tty to
* raw mode). This helps work around poorly behaved programs that
* catch SIGTTOU/SIGTTIN but suspend themselves with SIGSTOP. At
* worst, sudo will go into the background but upon resume the
* command will be runnable. Otherwise, we can get into a
* situation where the command will immediately suspend itself.
*/
ret = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG;
break;
}
@@ -1249,7 +1252,6 @@ exec_pty(struct command_details *details, struct command_status *cstat)
if (sudo_term_raw(io_fds[SFD_USERTTY], 0))
ttymode = TERM_RAW;
}
tty_initialized = true;
}
/*