xref: /freebsd/lib/libc/string/strerror.c (revision 2357939bc239bd5334a169b62313806178dd8f30)
1 /*-
2  * Copyright (c) 1988, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char sccsid[] = "@(#)strerror.c	8.1 (Berkeley) 6/4/93";
36 #endif /* LIBC_SCCS and not lint */
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
39 
40 #include <errno.h>
41 #include <stdio.h>
42 #include <string.h>
43 
44 #define	UPREFIX		"Unknown error: "
45 
46 /*
47  * Define a buffer size big enough to describe a 64-bit signed integer
48  * converted to ASCII decimal (19 bytes), with an optional leading sign
49  * (1 byte); finally, we get the prefix and a trailing NUL from UPREFIX.
50  */
51 #define	EBUFSIZE	(20 + sizeof(UPREFIX))
52 
53 /*
54  * Doing this by hand instead of linking with stdio(3) avoids bloat for
55  * statically linked binaries.
56  */
57 static void
58 errstr(int num, char *buf, size_t len)
59 {
60 	char *t;
61 	unsigned int uerr;
62 	char tmp[EBUFSIZE];
63 
64 	t = tmp + sizeof(tmp);
65 	*--t = '\0';
66 	uerr = (num >= 0) ? num : -num;
67 	do {
68 		*--t = "0123456789"[uerr % 10];
69 	} while (uerr /= 10);
70 	if (num < 0)
71 		*--t = '-';
72 	strlcpy(buf, UPREFIX, len);
73 	strlcat(buf, t, len);
74 }
75 
76 int
77 strerror_r(int errnum, char *strerrbuf, size_t buflen)
78 {
79 
80 	if (errnum < 1 || errnum >= sys_nerr) {
81 		errstr(errnum, strerrbuf, buflen);
82 		return (EINVAL);
83 	}
84 	if (strlcpy(strerrbuf, sys_errlist[errnum], buflen) >= buflen)
85 		return (ERANGE);
86 	return (0);
87 }
88 
89 char *
90 strerror(int num)
91 {
92 	static char ebuf[EBUFSIZE];
93 
94 	if (num > 0 && num < sys_nerr)
95 		return ((char *)sys_errlist[num]);
96 	errno = EINVAL;
97 	errstr(num, ebuf, sizeof(ebuf));
98 	return (ebuf);
99 }
100