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 * Copyright 2022 Oxide Computer Company 26 */ 27 28 /* Copyright (c) 1988 AT&T */ 29 /* All Rights Reserved */ 30 31 #pragma weak _isatty = isatty 32 33 #include "lint.h" 34 #include <sys/types.h> 35 #include <sys/termio.h> 36 #include <errno.h> 37 #include <unistd.h> 38 39 /* 40 * Returns 1 iff file is a tty 41 */ 42 int 43 isatty(int f) 44 { 45 struct termio tty; 46 47 if (ioctl(f, TCGETA, &tty) < 0) { 48 /* 49 * POSIX stipulates that systems may return an error here and if 50 * they do, it should either be EBADF or ENOTTY. In general, we 51 * assume that a driver that receives this ioctl is not going to 52 * return EBADF say due to an fd that's not open with the right 53 * mode and will instead return something else. It is possible 54 * to get many other errors here and we assume anything else 55 * that's returned means it's not a TTY and thus transform that. 56 * 57 * In the past, errno was preserved around this, which was 58 * incorrect because that meant that on failure there was no way 59 * to know whether it was meaningful or not. As pretty much 60 * every other system always returns an errno and there are 61 * consumers in the wild which assume they'll get something, we 62 * opt to always return an error. 63 */ 64 if (errno != EBADF) { 65 errno = ENOTTY; 66 } 67 return (0); 68 } 69 return (1); 70 } 71