freebsd-dev/lib/libc/gen/ttyname.c
Ed Schouten 26d4f5e969 Add two new routines: fdevname() and fdevname_r().
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
2009-02-11 20:24:59 +00:00

111 lines
3.2 KiB
C

/*
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)ttyname.c 8.2 (Berkeley) 1/27/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/filio.h>
#include <fcntl.h>
#include <dirent.h>
#include <stdlib.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <paths.h>
#include <errno.h>
#include "reentrant.h"
#include "un-namespace.h"
#include "libc_private.h"
static char ttyname_buf[sizeof(_PATH_DEV) + MAXNAMLEN];
static once_t ttyname_init_once = ONCE_INITIALIZER;
static thread_key_t ttyname_key;
static int ttyname_keycreated = 0;
int
ttyname_r(int fd, char *buf, size_t len)
{
size_t used;
*buf = '\0';
/* Must be a terminal. */
if (!isatty(fd))
return (ENOTTY);
/* Must have enough room */
if (len <= sizeof(_PATH_DEV))
return (ERANGE);
strcpy(buf, _PATH_DEV);
used = strlen(buf);
if (fdevname_r(fd, buf + used, len - used) == NULL)
return (ENOTTY);
return (0);
}
static void
ttyname_keycreate(void)
{
ttyname_keycreated = (thr_keycreate(&ttyname_key, free) == 0);
}
char *
ttyname(int fd)
{
char *buf;
if (thr_main() != 0)
buf = ttyname_buf;
else {
if (thr_once(&ttyname_init_once, ttyname_keycreate) != 0 ||
!ttyname_keycreated)
return (NULL);
if ((buf = thr_getspecific(ttyname_key)) == NULL) {
if ((buf = malloc(sizeof ttyname_buf)) == NULL)
return (NULL);
if (thr_setspecific(ttyname_key, buf) != 0) {
free(buf);
return (NULL);
}
}
}
if (ttyname_r(fd, buf, sizeof ttyname_buf) != 0)
return (NULL);
return (buf);
}