26d4f5e969
A more elegant way of obtaining a name of a character device by its file descriptor on FreeBSD, is to use the FIODGNAME ioctl. Because a valid file descriptor implies a file descriptor is visible in /dev, it will always resolve a valid device name. I'm adding a more friendly wrapper for this ioctl, called fdevname(). It is a lot easier to use than devname() and also has better error handling. When a device name cannot be resolved, it will just return NULL instead of a generated device name that makes no sense. Discussed with: kib
94 lines
2.9 KiB
C
94 lines
2.9 KiB
C
/*-
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* Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
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* All rights reserved.
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*
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* Portions of this software were developed under sponsorship from Snow
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* B.V., the Netherlands.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__FBSDID("$FreeBSD$");
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#endif /* not lint */
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#include "namespace.h"
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#include <sys/param.h>
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#include <sys/ioctl.h>
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#include <errno.h>
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#include <paths.h>
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#include <stdlib.h>
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#include "un-namespace.h"
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/*
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* __isptmaster(): return whether the file descriptor refers to a
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* pseudo-terminal master device.
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*/
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static int
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__isptmaster(int fildes)
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{
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if (_ioctl(fildes, TIOCPTMASTER) == 0)
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return (0);
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if (errno != EBADF)
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errno = EINVAL;
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return (-1);
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}
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/*
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* In our implementation, grantpt() and unlockpt() don't actually have
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* any use, because PTY's are created on the fly and already have proper
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* permissions upon creation.
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*
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* Just make sure `fildes' actually points to a real PTY master device.
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*/
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__strong_reference(__isptmaster, grantpt);
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__strong_reference(__isptmaster, unlockpt);
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/*
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* ptsname(): return the pathname of the slave pseudo-terminal device
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* associated with the specified master.
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*/
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char *
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ptsname(int fildes)
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{
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static char pt_slave[sizeof _PATH_DEV + SPECNAMELEN] = _PATH_DEV;
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char *ret = NULL;
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int sverrno = errno;
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/* Make sure fildes points to a master device. */
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if (__isptmaster(fildes) != 0)
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goto done;
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if (fdevname_r(fildes, pt_slave + (sizeof _PATH_DEV - 1),
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sizeof pt_slave - (sizeof _PATH_DEV - 1)) != NULL)
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ret = pt_slave;
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done: /* Make sure ptsname() does not overwrite errno. */
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errno = sverrno;
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return (ret);
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}
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