freebsd-skq/lib/libc/stdlib/ptsname.c
emaste ed3f0cd13d According to a clarification at http://austingroupbugs.net/view.php?id=503
ptsname may set errno, so avoid saving and restoring errno across the
function.

PR:		standards/171572
2012-09-12 17:54:09 +00:00

92 lines
2.8 KiB
C

/*-
* Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
* All rights reserved.
*
* Portions of this software were developed under sponsorship from Snow
* B.V., the Netherlands.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__FBSDID("$FreeBSD$");
#endif /* not lint */
#include "namespace.h"
#include <sys/param.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <paths.h>
#include <stdlib.h>
#include "un-namespace.h"
/*
* __isptmaster(): return whether the file descriptor refers to a
* pseudo-terminal master device.
*/
static int
__isptmaster(int fildes)
{
if (_ioctl(fildes, TIOCPTMASTER) == 0)
return (0);
if (errno != EBADF)
errno = EINVAL;
return (-1);
}
/*
* In our implementation, grantpt() and unlockpt() don't actually have
* any use, because PTY's are created on the fly and already have proper
* permissions upon creation.
*
* Just make sure `fildes' actually points to a real PTY master device.
*/
__strong_reference(__isptmaster, grantpt);
__strong_reference(__isptmaster, unlockpt);
/*
* ptsname(): return the pathname of the slave pseudo-terminal device
* associated with the specified master.
*/
char *
ptsname(int fildes)
{
static char pt_slave[sizeof _PATH_DEV + SPECNAMELEN] = _PATH_DEV;
char *ret = NULL;
/* Make sure fildes points to a master device. */
if (__isptmaster(fildes) != 0)
goto done;
if (fdevname_r(fildes, pt_slave + (sizeof _PATH_DEV - 1),
sizeof pt_slave - (sizeof _PATH_DEV - 1)) != NULL)
ret = pt_slave;
done:
return (ret);
}