lib/libc/gen/ttyname.c

   1 /*      $NetBSD: ttyname.c,v 1.26 2012/06/12 18:17:04 joerg Exp $       */
   2
   3 /*
   4  * Copyright (c) 1988, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the name of the University nor the names of its contributors
  16  *    may be used to endorse or promote products derived from this software
  17  *    without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29  * SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "@(#)ttyname.c   8.2 (Berkeley) 1/27/94";
  36 #else
  37 __RCSID("$NetBSD: ttyname.c,v 1.26 2012/06/12 18:17:04 joerg Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include "namespace.h"
  42 #include <sys/ioctl.h>
  43 #include <sys/stat.h>
  44
  45 #include <assert.h>
  46 #include <errno.h>
  47 #include <limits.h>
  48 #include <paths.h>
  49 #include <string.h>
  50 #include <stdlib.h>
  51 #include <termios.h>
  52 #include <unistd.h>
  53
  54 #ifdef __weak_alias
  55 __weak_alias(ttyname,_ttyname)
  56 __weak_alias(ttyname_r,_ttyname_r)
  57 #endif
  58
  59 int
  60 ttyname_r(int fd, char *buf, size_t len)
  61 {
  62         struct stat sb;
  63         struct termios ttyb;
  64         struct ptmget ptm;
  65
  66         _DIAGASSERT(fd != -1);
  67
  68         /* If it is a pty, deal with it quickly */
  69         if (ioctl(fd, TIOCPTSNAME, &ptm) != -1) {
  70                 if (strlcpy(buf, ptm.sn, len) >= len) {
  71                         return ERANGE;
  72                 }
  73                 return 0;
  74         }
  75
  76         /* Must be a terminal. */
  77         if (tcgetattr(fd, &ttyb) == -1)
  78                 return errno;
  79
  80         if (fstat(fd, &sb))
  81                 return errno;
  82
  83         if (strlcpy(buf, _PATH_DEV, len) >= len)
  84                 return ERANGE;
  85         buf += strlen(_PATH_DEV);
  86         len -= strlen(_PATH_DEV);
  87         return devname_r(sb.st_rdev, sb.st_mode & S_IFMT, buf, len);
  88 }
  89
  90 char *
  91 ttyname(int fd)
  92 {
  93         static char buf[PATH_MAX];
  94         int rv;
  95
  96         rv = ttyname_r(fd, buf, sizeof(buf));
  97         if (rv != 0) {
  98                 errno = rv;
  99                 return NULL;
 100         }
 101         return buf;
 102 }