usr/src/lib/libc/port/gen/isastream.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*
  33  * Check to see if a file descriptor is that of a stream.
  34  * Return 1 with errno set to 0 if it is. Otherwise,
  35  * return 0 with errno set to 0.
  36  * The only error returned is that case of a bad file desc.
  37  *
  38  */
  39
  40 #pragma weak _isastream = isastream
  41
  42 #include "lint.h"
  43 #include <sys/types.h>
  44 #include <stdio.h>
  45 #include <errno.h>
  46 #include <stropts.h>
  47
  48 int
  49 isastream(int fd)
  50 {
  51         int rval;
  52
  53         rval = ioctl(fd, I_CANPUT, 0);
  54         if (rval == -1 && errno == EBADF)
  55                 return (-1);
  56
  57         errno = 0;
  58         if (rval == 0 || rval == 1)
  59                 return (1);
  60
  61         return (0);
  62 }