xref: /freebsd/lib/libc/stdio/gets_s.c (revision ddfc6f84f24215b418af19260e9156219f6df03e)
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  * Copyright (c) 2017, 2018
7  *	Cyril S. E. Schubert
8  *
9  * This code is derived from software contributed to Berkeley by
10  * Chris Torek.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. Neither the name of the University nor the names of its contributors
21  *    may be used to endorse or promote products derived from this software
22  *    without specific prior written permission.
23  *
24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34  * SUCH DAMAGE.
35  */
36 
37 #include "namespace.h"
38 #include <errno.h>
39 #include <unistd.h>
40 #include <stdint.h>
41 #include <stdio.h>
42 #include <ssp/ssp.h>
43 #include "un-namespace.h"
44 #include "libc_private.h"
45 #include "local.h"
46 
47 static inline char *
48 _gets_s(char *buf, rsize_t n)
49 {
50 	int c;
51 	char *s;
52 
53 	ORIENT(stdin, -1);
54 	for (s = buf, n--; (c = __sgetc(stdin)) != '\n' && n > 0 ; n--) {
55 		if (c == EOF) {
56 			if (s == buf) {
57 				return (NULL);
58 			} else
59 				break;
60 		} else
61 			*s++ = c;
62 	}
63 
64 	/*
65  	 * If end of buffer reached, discard until \n or eof.
66 	 * Then throw an error.
67 	 */
68 	if (n == 0) {
69 		/* discard */
70 		while ((c = __sgetc(stdin)) != '\n' && c != EOF);
71 		/* throw the error after lock released prior to exit */
72 		__throw_constraint_handler_s("gets_s : end of buffer", E2BIG);
73 		return (NULL);
74 	}
75 	*s = 0;
76 	return (buf);
77 }
78 
79 /* ISO/IEC 9899:2011 K.3.7.4.1 */
80 char *
81 __ssp_real(gets_s)(char *buf, rsize_t n)
82 {
83 	char *ret;
84 	if (buf == NULL) {
85 		__throw_constraint_handler_s("gets_s : str is NULL", EINVAL);
86 		return(NULL);
87 	} else if (n > RSIZE_MAX) {
88 		__throw_constraint_handler_s("gets_s : n > RSIZE_MAX",
89 			EINVAL);
90 		return(NULL);
91 	} else if (n == 0) {
92 		__throw_constraint_handler_s("gets_s : n == 0", EINVAL);
93 		return(NULL);
94 	}
95 
96 	FLOCKFILE_CANCELSAFE(stdin);
97 	ret = _gets_s(buf, n);
98 	FUNLOCKFILE_CANCELSAFE();
99 	return (ret);
100 }
101