strerror.c revision 108118 
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)
35static 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: head/lib/libc/string/strerror.c 108118 2002-12-20 05:26:10Z mike $");
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 */
57static void
58errstr(int num, char *buf, size_t len)
59{
60	char *p, *t;
61	unsigned int uerr;
62	char tmp[EBUFSIZE];
63
64	if (strlcpy(buf, UPREFIX, len) >= len)
65		return;
66	t = tmp;
67	uerr = (num >= 0) ? num : -num;
68	do {
69		*t++ = "0123456789"[uerr % 10];
70	} while (uerr /= 10);
71	if (num < 0)
72		*t++ = '-';
73	for (p = buf + sizeof(UPREFIX) - 1; t > tmp && p < buf + len - 1;)
74		*p++ = *--t;
75	*p = '\0';
76}
77
78int
79strerror_r(int errnum, char *strerrbuf, size_t buflen)
80{
81
82	if (errnum < 1 || errnum >= sys_nerr) {
83		errstr(errnum, strerrbuf, buflen);
84		return (EINVAL);
85	}
86	if (strlcpy(strerrbuf, sys_errlist[errnum], buflen) >= buflen)
87		return (ERANGE);
88	return (0);
89}
90
91char *
92strerror(int num)
93{
94	static char ebuf[EBUFSIZE];
95
96	if (num > 0 && num < sys_nerr)
97		return ((char *)sys_errlist[num]);
98	errno = EINVAL;
99	errstr(num, ebuf, sizeof(ebuf));
100	return (ebuf);
101}
102