1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)fgets.c	8.2 (Berkeley) 12/22/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD$");
38
39#include "namespace.h"
40#include <stdio.h>
41#include <string.h>
42#include "un-namespace.h"
43#include "local.h"
44#include "libc_private.h"
45
46/*
47 * Read at most n-1 characters from the given file.
48 * Stop when a newline has been read, or the count runs out.
49 * Return first argument, or NULL if no characters were read.
50 */
51char *
52fgets(char * __restrict buf, int n, FILE * __restrict fp)
53{
54	size_t len;
55	char *s;
56	unsigned char *p, *t;
57
58	if (n <= 0)		/* sanity check */
59		return (NULL);
60
61	FLOCKFILE(fp);
62	ORIENT(fp, -1);
63	s = buf;
64	n--;			/* leave space for NUL */
65	while (n != 0) {
66		/*
67		 * If the buffer is empty, refill it.
68		 */
69		if ((len = fp->_r) <= 0) {
70			if (__srefill(fp)) {
71				/* EOF/error: stop with partial or no line */
72				if (s == buf) {
73					FUNLOCKFILE(fp);
74					return (NULL);
75				}
76				break;
77			}
78			len = fp->_r;
79		}
80		p = fp->_p;
81
82		/*
83		 * Scan through at most n bytes of the current buffer,
84		 * looking for '\n'.  If found, copy up to and including
85		 * newline, and stop.  Otherwise, copy entire chunk
86		 * and loop.
87		 */
88		if (len > n)
89			len = n;
90		t = memchr((void *)p, '\n', len);
91		if (t != NULL) {
92			len = ++t - p;
93			fp->_r -= len;
94			fp->_p = t;
95			(void)memcpy((void *)s, (void *)p, len);
96			s[len] = 0;
97			FUNLOCKFILE(fp);
98			return (buf);
99		}
100		fp->_r -= len;
101		fp->_p += len;
102		(void)memcpy((void *)s, (void *)p, len);
103		s += len;
104		n -= len;
105	}
106	*s = 0;
107	FUNLOCKFILE(fp);
108	return (buf);
109}
110