strerror.c revision 86944 
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 86944 2001-11-27 07:39:46Z wes $");
39
40#include <stdio.h>
41#include <string.h>
42#include <errno.h>
43
44
45int
46strerror_r(int errnum, char *strerrbuf, size_t buflen)
47{
48#define	UPREFIX	"Unknown error: "
49	unsigned int uerr;
50	char *p, *t;
51	char tmp[40];				/* 64-bit number + slop */
52	int len;
53
54	uerr = errnum;				/* convert to unsigned */
55	if (uerr < sys_nerr) {
56		len = strlcpy(strerrbuf, (char *)sys_errlist[uerr], buflen);
57		return (len <= buflen) ? 0 : ERANGE;
58	}
59
60	/* Print unknown errno by hand so we don't link to stdio(3). */
61	t = tmp;
62	if (errnum < 0)
63		uerr = -uerr;
64	do {
65		*t++ = "0123456789"[uerr % 10];
66	} while (uerr /= 10);
67
68	if (errnum < 0)
69		*t++ = '-';
70
71	strlcpy(strerrbuf, UPREFIX, buflen);
72	for (p = strerrbuf + sizeof(UPREFIX) - 1; p < strerrbuf + buflen; ) {
73		*p++ = *--t;
74		if (t <= tmp)
75			break;
76	}
77
78	if (p < strerrbuf + buflen) {
79		*p = '\0';
80		return 0;
81	}
82
83	return ERANGE;
84}
85
86
87/*
88 * NOTE: the following length should be enough to hold the longest defined
89 * error message in sys_errlist, defined in ../gen/errlst.c.  This is a WAG
90 * that is better than the previous value.
91 */
92#define ERR_LEN 64
93
94char *
95strerror(num)
96	int num;
97{
98	unsigned int uerr;
99	static char ebuf[ERR_LEN];
100
101	uerr = num;				/* convert to unsigned */
102	if (uerr < sys_nerr)
103		return (char *)sys_errlist[uerr];
104
105	/* strerror can't fail so handle truncation semi-elegantly */
106	if (strerror_r(num, ebuf, (size_t) ERR_LEN) != 0)
107	    ebuf[ERR_LEN - 1] = '\0';
108
109	return ebuf;
110}
111
112
113#ifdef STANDALONE_TEST
114main()
115{
116	char mybuf[64];
117	int ret;
118
119	printf("strerror(47) yeilds: %s\n", strerror(47));
120	strerror_r(11, mybuf, 64);
121	printf("strerror_r(11) yeilds: %s\n", mybuf);
122	strerror_r(1234, mybuf, 64);
123	printf("strerror_r(1234) yeilds: %s\n", mybuf);
124	memset(mybuf, '*', 63);
125	ret = strerror_r(4321, mybuf, 16);
126	printf("strerror_r on short buffer returns %d (%s)\n", ret, mybuf);
127}
128#endif
129