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Revert "logind: become the controlling terminal process before restoring VT"

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This reverts commit ad96887a12.

Commit adb8688 alone should be enough to fix issue #9754.

Fixes #11269
This commit is contained in:
Franck Bui 2019-01-10 12:17:51 +01:00 committed by Zbigniew Jędrzejewski-Szmek
parent c7e93c4d15
commit c0f34168d4
1 changed files with 16 additions and 44 deletions
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60
src/login/logind-session.c
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@ -1227,54 +1227,26 @@ error:
}
static void session_restore_vt(Session *s) {
pid_t pid;
int r;
int r, vt, old_fd;
if (s->vtnr < 1)
/* We need to get a fresh handle to the virtual terminal,
* since the old file-descriptor is potentially in a hung-up
* state after the controlling process exited; we do a
* little dance to avoid having the terminal be available
* for reuse before we've cleaned it up.
*/
old_fd = TAKE_FD(s->vtfd);
vt = session_open_vt(s);
safe_close(old_fd);
if (vt < 0)
return;
if (s->vtfd < 0)
return;
r = vt_restore(vt);
if (r < 0)
log_warning_errno(r, "Failed to restore VT, ignoring: %m");
/* The virtual terminal can potentially be entering in hung-up state at any time
* depending on when the controlling process exits.
*
* If the controlling process exits while we're restoring the virtual terminal,
* the VT will enter in hung-up state and we'll fail at restoring it. To prevent
* this case, we kick off the current controlling process (if any) in a child
* process so logind doesn't play around with tty ownership.
*
* If the controlling process already exited, getting a fresh handle to the
* virtual terminal reset the hung-up state. */
r = safe_fork("(logind)", FORK_REOPEN_LOG|FORK_CLOSE_ALL_FDS|FORK_RESET_SIGNALS|FORK_WAIT|FORK_LOG, &pid);
if (r == 0) {
char path[sizeof("/dev/tty") + DECIMAL_STR_MAX(s->vtnr)];
int vt;
/* We must be a session leader in order to become the controlling process. */
pid = setsid();
if (pid < 0) {
log_error_errno(errno, "Failed to become session leader: %m");
_exit(EXIT_FAILURE);
}
sprintf(path, "/dev/tty%u", s->vtnr);
vt = acquire_terminal(path, ACQUIRE_TERMINAL_FORCE, USEC_INFINITY);
if (vt < 0) {
log_error_errno(vt, "Cannot acquire VT %s of session %s: %m", path, s->id);
_exit(EXIT_FAILURE);
}
r = vt_restore(vt);
if (r < 0)
log_warning_errno(r, "Failed to restore VT, ignoring: %m");
/* Give up and release the controlling terminal. */
safe_close(vt);
_exit(EXIT_SUCCESS);
}
/* Close the fd in any cases. */
s->vtfd = safe_close(s->vtfd);
}