1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)fgets.c 8.2 (Berkeley) 12/22/93";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
40
41 #include "namespace.h"
42 #include <errno.h>
43 #include <stdio.h>
44 #include <string.h>
45 #include "un-namespace.h"
46 #include "local.h"
47 #include "libc_private.h"
48
49 /*
50 * Read at most n-1 characters from the given file.
51 * Stop when a newline has been read, or the count runs out.
52 * Return first argument, or NULL if no characters were read.
53 */
54 char *
fgets(char * __restrict buf,int n,FILE * __restrict fp)55 fgets(char * __restrict buf, int n, FILE * __restrict fp)
56 {
57 size_t len;
58 char *s, *ret;
59 unsigned char *p, *t;
60
61 FLOCKFILE_CANCELSAFE(fp);
62 ORIENT(fp, -1);
63
64 if (n <= 0) { /* sanity check */
65 fp->_flags |= __SERR;
66 errno = EINVAL;
67 ret = NULL;
68 goto end;
69 }
70
71 s = buf;
72 n--; /* leave space for NUL */
73 while (n != 0) {
74 /*
75 * If the buffer is empty, refill it.
76 */
77 if ((len = fp->_r) <= 0) {
78 if (__srefill(fp)) {
79 /* EOF/error: stop with partial or no line */
80 if (!__sfeof(fp) || s == buf) {
81 ret = NULL;
82 goto end;
83 }
84 break;
85 }
86 len = fp->_r;
87 }
88 p = fp->_p;
89
90 /*
91 * Scan through at most n bytes of the current buffer,
92 * looking for '\n'. If found, copy up to and including
93 * newline, and stop. Otherwise, copy entire chunk
94 * and loop.
95 */
96 if (len > n)
97 len = n;
98 t = memchr((void *)p, '\n', len);
99 if (t != NULL) {
100 len = ++t - p;
101 fp->_r -= len;
102 fp->_p = t;
103 (void)memcpy((void *)s, (void *)p, len);
104 s[len] = 0;
105 ret = buf;
106 goto end;
107 }
108 fp->_r -= len;
109 fp->_p += len;
110 (void)memcpy((void *)s, (void *)p, len);
111 s += len;
112 n -= len;
113 }
114 *s = 0;
115 ret = buf;
116 end:
117 FUNLOCKFILE_CANCELSAFE();
118 return (ret);
119 }
120