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// SPDX-FileCopyrightText: 2024, Skyler Ferrante <sjf5462@rit.edu>
// SPDX-License-Identifier: BSD-3-Clause
/**
* To protect against file descriptor omission attacks, we open the std file
* descriptors with /dev/null if they are not already open. Code is based on
* fix_fds from sudo.c.
*/
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include "prototypes.h"
static void check_fd(int fd);
void
check_fds(void)
{
/**
* Make sure stdin, stdout, stderr are open
* If they are closed, set them to /dev/null
*/
check_fd(STDIN_FILENO);
check_fd(STDOUT_FILENO);
check_fd(STDERR_FILENO);
}
static void
check_fd(int fd)
{
int devnull;
if (fcntl(fd, F_GETFL, 0) != -1)
return;
devnull = open("/dev/null", O_RDWR);
if (devnull != fd)
abort();
}
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