xref: /illumos-gate/usr/src/lib/libc/port/stdio/gets.c (revision edd580643f2cf1434e252cd7779e83182ea84945)
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 #include "lint.h"
33 #include "file64.h"
34 #include "mtlib.h"
35 #include <sys/types.h>
36 #include <stdio.h>
37 #include <memory.h>
38 #include <thread.h>
39 #include <synch.h>
40 #include <errno.h>
41 #include "stdiom.h"
42 #include "mse.h"
43 
44 /* read a single line from stdin, replace the '\n' with '\0' */
45 char *
46 gets(char *buf)
47 {
48 	char *ptr = buf;
49 	ssize_t n;
50 	char *p;
51 	Uchar *bufend;
52 	rmutex_t *lk;
53 
54 	FLOCKFILE(lk, stdin);
55 
56 	_SET_ORIENTATION_BYTE(stdin);
57 
58 	if (!(stdin->_flag & (_IOREAD | _IORW))) {
59 		errno = EBADF;
60 		FUNLOCKFILE(lk);
61 		return (0);
62 	}
63 
64 	if (stdin->_base == NULL) {
65 		if ((bufend = _findbuf(stdin)) == 0) {
66 			FUNLOCKFILE(lk);
67 			return (0);
68 		}
69 	}
70 	else
71 		bufend = _bufend(stdin);
72 
73 	for (;;)	/* until get a '\n' */
74 	{
75 		if (stdin->_cnt <= 0)	/* empty buffer */
76 		{
77 			if (__filbuf(stdin) != EOF) {
78 				stdin->_ptr--;	/* put back the character */
79 				stdin->_cnt++;
80 			} else if (ptr == buf) {  /* never read anything */
81 				FUNLOCKFILE(lk);
82 				return (0);
83 			} else
84 				break;		/* nothing left to read */
85 		}
86 		n = stdin->_cnt;
87 		if ((p = (char *)memccpy(ptr, (char *)stdin->_ptr, '\n',
88 		    (size_t)n)) != 0)
89 			n = p - ptr;
90 		ptr += n;
91 		stdin->_cnt -= n;
92 		stdin->_ptr += n;
93 		if (_needsync(stdin, bufend))
94 			_bufsync(stdin, bufend);
95 		if (p != 0) /* found a '\n' */
96 		{
97 			ptr--;	/* step back over the '\n' */
98 			break;
99 		}
100 	}
101 	*ptr = '\0';
102 	FUNLOCKFILE(lk);
103 	return (buf);
104 }
105