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/*
* Replacement for a missing daemon.
*
* Provides the same functionality as the library function daemon for those
* systems that don't have it.
*
* The canonical version of this file is maintained in the rra-c-util package,
* which can be found at <http://www.eyrie.org/~eagle/software/rra-c-util/>.
*
* Written by Russ Allbery <eagle@eyrie.org>
*
* The authors hereby relinquish any claim to any copyright that they may have
* in this work, whether granted under contract or by operation of law or
* international treaty, and hereby commit to the public, at large, that they
* shall not, at any time in the future, seek to enforce any copyright in this
* work against any person or entity, or prevent any person or entity from
* copying, publishing, distributing or creating derivative works of this
* work.
*/
#include <config.h>
#include <portable/system.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
/*
* If we're running the test suite, rename daemon to avoid conflicts with the
* system version. #undef it first because some systems may define it to
* another name.
*/
#if TESTING
# undef daemon
# define daemon test_daemon
int test_daemon(int, int);
#endif
int
daemon(int nochdir, int noclose)
{
int status, fd;
/*
* Fork and exit in the parent to disassociate from the current process
* group and become the leader of a new process group.
*/
status = fork();
if (status < 0)
return -1;
else if (status > 0)
_exit(0);
/*
* setsid() should take care of disassociating from the controlling
* terminal, and FreeBSD at least doesn't like TIOCNOTTY if you don't
* already have a controlling terminal. So only use the older TIOCNOTTY
* method if setsid() isn't available.
*/
#if HAVE_SETSID
if (setsid() < 0)
return -1;
#elif defined(TIOCNOTTY)
fd = open("/dev/tty", O_RDWR);
if (fd >= 0) {
if (ioctl(fd, TIOCNOTTY, NULL) < 0) {
status = errno;
close(fd);
errno = status;
return -1;
}
close(fd);
}
#endif /* defined(TIOCNOTTY) */
if (!nochdir && chdir("/") < 0)
return -1;
if (!noclose) {
fd = open("/dev/null", O_RDWR, 0);
if (fd < 0)
return -1;
else {
if (dup2(fd, STDIN_FILENO) < 0)
return -1;
if (dup2(fd, STDOUT_FILENO) < 0)
return -1;
if (dup2(fd, STDERR_FILENO) < 0)
return -1;
if (fd > 2)
close(fd);
}
}
return 0;
}
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