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 * @(#)fgets.c 8.2 (Berkeley) 12/22/93
33 * $FreeBSD: src/lib/libc/stdio/fgets.c,v 1.14 2007/01/09 00:28:06 imp Exp $
34 */
35
36 #include "namespace.h"
37 #include <stdio.h>
38 #include <string.h>
39 #include "un-namespace.h"
40 #include "local.h"
41 #include "libc_private.h"
42
43 /*
44 * Read at most n-1 characters from the given file.
45 * Stop when a newline has been read, or the count runs out.
46 * Return first argument, or NULL if no characters were read.
47 */
48 char *
fgets(char * buf,int n,FILE * fp)49 fgets(char *buf, int n, FILE *fp)
50 {
51 size_t len;
52 char *s;
53 unsigned char *p, *t;
54
55 if (n <= 0) /* sanity check */
56 return (NULL);
57
58 FLOCKFILE(fp);
59 ORIENT(fp, -1);
60 s = buf;
61 n--; /* leave space for NUL */
62 while (n != 0) {
63 /*
64 * If the buffer is empty, refill it.
65 */
66 if ((len = fp->pub._r) <= 0) {
67 if (__srefill(fp)) {
68 /* EOF/error: stop with partial or no line */
69 if (s == buf) {
70 FUNLOCKFILE(fp);
71 return (NULL);
72 }
73 break;
74 }
75 len = fp->pub._r;
76 }
77 p = fp->pub._p;
78
79 /*
80 * Scan through at most n bytes of the current buffer,
81 * looking for '\n'. If found, copy up to and including
82 * newline, and stop. Otherwise, copy entire chunk
83 * and loop.
84 */
85 if (len > n)
86 len = n;
87 t = memchr((void *)p, '\n', len);
88 if (t != NULL) {
89 len = ++t - p;
90 fp->pub._r -= len;
91 fp->pub._p = t;
92 memcpy((void *)s, (void *)p, len);
93 s[len] = 0;
94 FUNLOCKFILE(fp);
95 return (buf);
96 }
97 fp->pub._r -= len;
98 fp->pub._p += len;
99 memcpy((void *)s, (void *)p, len);
100 s += len;
101 n -= len;
102 }
103 *s = 0;
104 FUNLOCKFILE(fp);
105 return (buf);
106 }
107