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Move updating of the window size back to the main sudo process.

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We can use the leader file descriptor with TIOCGWINSZ to set the
window size of the pty.  Thanks to Duncan Overbruck for the hint.
This commit is contained in:
Todd C. Miller
2023-03-21 15:30:54 -06:00
parent c64993a0b3
commit adb84293ab
3 changed files with 18 additions and 66 deletions
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60
src/exec_monitor.c
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@@ -24,7 +24,6 @@
#include <config.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <stdio.h>
@@ -35,7 +34,6 @@
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include "sudo.h"
#include "sudo_exec.h"
@@ -62,8 +60,6 @@ struct monitor_closure {
int backchannel;
};
static bool tty_initialized;
/*
* Deliver a signal to the running command.
* The signal was either forwarded to us by the parent sudo process
@@ -103,11 +99,6 @@ deliver_signal(struct monitor_closure *mc, int signo, bool from_parent)
"%s: unable to set foreground pgrp to %d (command)",
__func__, (int)mc->cmnd_pgrp);
}
/* Lazily initialize the pty if needed. */
if (!tty_initialized) {
if (sudo_term_copy(io_fds[SFD_USERTTY], io_fds[SFD_FOLLOWER]))
tty_initialized = true;
}
killpg(mc->cmnd_pid, SIGCONT);
break;
case SIGCONT_BG:
@@ -130,34 +121,6 @@ deliver_signal(struct monitor_closure *mc, int signo, bool from_parent)
debug_return;
}
/*
* Unpack rows and cols from a CMD_TTYWINCH value, set the new window
* size on the pty follower and inform the command of the change.
*/
static void
handle_winch(struct monitor_closure *mc, unsigned int wsize_packed)
{
struct winsize wsize, owsize;
debug_decl(handle_winch, SUDO_DEBUG_EXEC);
/* Rows and columns are stored as two shorts packed into a single int. */
wsize.ws_row = wsize_packed & 0xffff;
wsize.ws_col = (wsize_packed >> 16) & 0xffff;
if (ioctl(io_fds[SFD_FOLLOWER], TIOCGWINSZ, &owsize) == 0 &&
(wsize.ws_row != owsize.ws_row || wsize.ws_col != owsize.ws_col)) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"window size change %dx%d -> %dx%d",
owsize.ws_col, owsize.ws_row, wsize.ws_col, wsize.ws_row);
(void)ioctl(io_fds[SFD_FOLLOWER], TIOCSWINSZ, &wsize);
deliver_signal(mc, SIGWINCH, true);
}
debug_return;
}
/*
* Send status to parent over socketpair.
* Return value is the same as send(2).
@@ -368,16 +331,11 @@ mon_backchannel_cb(int fd, int what, void *v)
mc->cstat->val = n ? EIO : ECONNRESET;
sudo_ev_loopbreak(mc->evbase);
} else {
switch (cstmp.type) {
case CMD_TTYWINCH:
handle_winch(mc, cstmp.val);
break;
case CMD_SIGNO:
if (cstmp.type == CMD_SIGNO) {
deliver_signal(mc, cstmp.val, true);
break;
default:
sudo_warnx(U_("unexpected reply type on backchannel: %d"), cstmp.type);
break;
} else {
sudo_warnx(U_("unexpected reply type on backchannel: %d"),
cstmp.type);
}
}
debug_return;
@@ -556,9 +514,11 @@ exec_monitor(struct command_details *details, sigset_t *oset,
int errpipe[2];
debug_decl(exec_monitor, SUDO_DEBUG_EXEC);
/* The pty leader is not used by the monitor. */
/* Close fds the monitor doesn't use. */
if (io_fds[SFD_LEADER] != -1)
close(io_fds[SFD_LEADER]);
if (io_fds[SFD_USERTTY] != -1)
close(io_fds[SFD_USERTTY]);
/* Ignore any SIGTTIN or SIGTTOU we receive (shouldn't be possible). */
memset(&sa, 0, sizeof(sa));
@@ -570,10 +530,6 @@ exec_monitor(struct command_details *details, sigset_t *oset,
if (sudo_sigaction(SIGTTOU, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGTTOU);
/* If we are starting in the foreground, the pty was already initialized. */
if (foreground)
tty_initialized = true;
/*
* Start a new session with the parent as the session leader
* and the follower device as the controlling terminal.
@@ -630,8 +586,6 @@ exec_monitor(struct command_details *details, sigset_t *oset,
/* child */
close(backchannel);
close(errpipe[0]);
if (io_fds[SFD_USERTTY] != -1)
close(io_fds[SFD_USERTTY]);
/* setup tty and exec command */
exec_cmnd_pty(details, oset, foreground, intercept_fd, errpipe[1]);
if (write(errpipe[1], &errno, sizeof(int)) == -1)