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 #include "namespace.h"
36 #include <errno.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 #undef fgets /* _FORTIFY_SOURCE */
44
45 /*
46 * Read at most n-1 characters from the given file.
47 * Stop when a newline has been read, or the count runs out.
48 * Return first argument, or NULL if no characters were read.
49 */
50 char *
fgets(char * __restrict buf,int n,FILE * __restrict fp)51 fgets(char * __restrict buf, int n, FILE * __restrict fp)
52 {
53 size_t len;
54 char *s, *ret;
55 unsigned char *p, *t;
56
57 FLOCKFILE_CANCELSAFE(fp);
58 ORIENT(fp, -1);
59
60 if (n <= 0) { /* sanity check */
61 fp->_flags |= __SERR;
62 errno = EINVAL;
63 ret = NULL;
64 goto end;
65 }
66
67 s = buf;
68 n--; /* leave space for NUL */
69 while (n != 0) {
70 /*
71 * If the buffer is empty, refill it.
72 */
73 if ((len = fp->_r) <= 0) {
74 if (__srefill(fp)) {
75 /* EOF/error: stop with partial or no line */
76 if (!__sfeof(fp) || s == buf) {
77 ret = NULL;
78 goto end;
79 }
80 break;
81 }
82 len = fp->_r;
83 }
84 p = fp->_p;
85
86 /*
87 * Scan through at most n bytes of the current buffer,
88 * looking for '\n'. If found, copy up to and including
89 * newline, and stop. Otherwise, copy entire chunk
90 * and loop.
91 */
92 if (len > n)
93 len = n;
94 t = memchr((void *)p, '\n', len);
95 if (t != NULL) {
96 len = ++t - p;
97 fp->_r -= len;
98 fp->_p = t;
99 (void)memcpy((void *)s, (void *)p, len);
100 s[len] = 0;
101 ret = buf;
102 goto end;
103 }
104 fp->_r -= len;
105 fp->_p += len;
106 (void)memcpy((void *)s, (void *)p, len);
107 s += len;
108 n -= len;
109 }
110 *s = 0;
111 ret = buf;
112 end:
113 FUNLOCKFILE_CANCELSAFE();
114 return (ret);
115 }
116