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 "namespace.h"
39 #include <errno.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 */
51 char *
fgets(char * __restrict buf,int n,FILE * __restrict fp)52 fgets(char * __restrict buf, int n, FILE * __restrict fp)
53 {
54 size_t len;
55 char *s, *ret;
56 unsigned char *p, *t;
57
58 FLOCKFILE_CANCELSAFE(fp);
59 ORIENT(fp, -1);
60
61 if (n <= 0) { /* sanity check */
62 fp->_flags |= __SERR;
63 errno = EINVAL;
64 ret = NULL;
65 goto end;
66 }
67
68 s = buf;
69 n--; /* leave space for NUL */
70 while (n != 0) {
71 /*
72 * If the buffer is empty, refill it.
73 */
74 if ((len = fp->_r) <= 0) {
75 if (__srefill(fp)) {
76 /* EOF/error: stop with partial or no line */
77 if (!__sfeof(fp) || s == buf) {
78 ret = NULL;
79 goto end;
80 }
81 break;
82 }
83 len = fp->_r;
84 }
85 p = fp->_p;
86
87 /*
88 * Scan through at most n bytes of the current buffer,
89 * looking for '\n'. If found, copy up to and including
90 * newline, and stop. Otherwise, copy entire chunk
91 * and loop.
92 */
93 if (len > n)
94 len = n;
95 t = memchr((void *)p, '\n', len);
96 if (t != NULL) {
97 len = ++t - p;
98 fp->_r -= len;
99 fp->_p = t;
100 (void)memcpy((void *)s, (void *)p, len);
101 s[len] = 0;
102 ret = buf;
103 goto end;
104 }
105 fp->_r -= len;
106 fp->_p += len;
107 (void)memcpy((void *)s, (void *)p, len);
108 s += len;
109 n -= len;
110 }
111 *s = 0;
112 ret = buf;
113 end:
114 FUNLOCKFILE_CANCELSAFE();
115 return (ret);
116 }
117