xref: /illumos-gate/usr/src/lib/libc/port/stdio/fgets.c (revision 7257d1b4)
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 <stdio.h>
36 #include <memory.h>
37 #include <errno.h>
38 #include <thread.h>
39 #include <synch.h>
40 #include <sys/types.h>
41 #include "stdiom.h"
42 #include "mse.h"
43 
44 /* read size-max line from stream, including '\n' */
45 char *
fgets(char * buf,int size,FILE * iop)46 fgets(char *buf, int size, FILE *iop)
47 {
48 	char *ptr = buf;
49 	int n;
50 	Uchar *bufend;
51 	char *p;
52 	rmutex_t *lk;
53 
54 	FLOCKFILE(lk, iop);
55 
56 	_SET_ORIENTATION_BYTE(iop);
57 
58 	if (!(iop->_flag & (_IOREAD | _IORW))) {
59 		errno = EBADF;
60 		FUNLOCKFILE(lk);
61 		return (NULL);
62 	}
63 
64 	if (iop->_base == NULL) {
65 		if ((bufend = _findbuf(iop)) == NULL) {
66 			FUNLOCKFILE(lk);
67 			return (NULL);
68 		}
69 	}
70 	else
71 		bufend = _bufend(iop);
72 
73 	size--;		/* room for '\0' */
74 	while (size > 0) {
75 		/* empty buffer */
76 		if (iop->_cnt <= 0) {
77 			if (__filbuf(iop) != EOF) {
78 				iop->_ptr--;	/* put back the character */
79 				iop->_cnt++;
80 			} else if (ptr == buf) {  /* never read anything */
81 				FUNLOCKFILE(lk);
82 				return (NULL);
83 			} else
84 				break;		/* nothing left to read */
85 		}
86 		n = (int)(size < iop->_cnt ? size : iop->_cnt);
87 		if ((p = memccpy(ptr, (char *)iop->_ptr, '\n',
88 		    (size_t)n)) != NULL)
89 			n = (int)(p - ptr);
90 		ptr += n;
91 		iop->_cnt -= n;
92 		iop->_ptr += n;
93 		if (_needsync(iop, bufend))
94 			_bufsync(iop, bufend);
95 		if (p != NULL)
96 			break; /* newline found */
97 		size -= n;
98 	}
99 	FUNLOCKFILE(lk);
100 	*ptr = '\0';
101 	return (buf);
102 }
103