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/*
* Copyright (c) 2017 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
# include <string.h>
#endif /* HAVE_STRING_H */
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif /* HAVE_STRINGS_H */
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include "sudo.h"
static volatile sig_atomic_t got_sigttou;
/*
* SIGTTOU signal handler for tcsetpgrp_nobg() that just sets a flag.
*/
static void
sigttou(int signo)
{
got_sigttou = 1;
}
/*
* Like tcsetpgrp() but restarts on EINTR _except_ for SIGTTOU.
* Returns 0 on success or -1 on failure, setting errno.
* Sets got_sigttou on failure if interrupted by SIGTTOU.
*/
int
tcsetpgrp_nobg(int fd, pid_t pgrp_id)
{
struct sigaction sa, osa;
int rc;
/*
* If we receive SIGTTOU from tcsetpgrp() it means we are
* not in the foreground process group.
* This avoid a TOCTOU race compared to using tcgetpgrp().
*/
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0; /* do not restart syscalls */
sa.sa_handler = sigttou;
got_sigttou = 0;
(void)sigaction(SIGTTOU, &sa, &osa);
do {
rc = tcsetpgrp(fd, pgrp_id);
} while (rc != 0 && errno == EINTR && !got_sigttou);
(void)sigaction(SIGTTOU, &osa, NULL);
return rc;
}
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