freebsd-dev/lib/libc/string/strerror.c
Mike Barcroft e37f8b5313 Optimize errstr() by reducing the number of times it walks a string.
As a side effect, it makes the code easier to read and requires less
pointer arithmetic.

Test by:	strerror regression test
Submitted by:	Tim Kientzle <kientzle@acm.org>
2003-01-03 16:44:42 +00:00

100 lines
3.2 KiB
C

/*-
* Copyright (c) 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)strerror.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <errno.h>
#include <stdio.h>
#include <string.h>
#define UPREFIX "Unknown error: "
/*
* Define a buffer size big enough to describe a 64-bit signed integer
* converted to ASCII decimal (19 bytes), with an optional leading sign
* (1 byte); finally, we get the prefix and a trailing NUL from UPREFIX.
*/
#define EBUFSIZE (20 + sizeof(UPREFIX))
/*
* Doing this by hand instead of linking with stdio(3) avoids bloat for
* statically linked binaries.
*/
static void
errstr(int num, char *buf, size_t len)
{
char *t;
unsigned int uerr;
char tmp[EBUFSIZE];
t = tmp + sizeof(tmp);
*--t = '\0';
uerr = (num >= 0) ? num : -num;
do {
*--t = "0123456789"[uerr % 10];
} while (uerr /= 10);
if (num < 0)
*--t = '-';
strlcpy(buf, UPREFIX, len);
strlcat(buf, t, len);
}
int
strerror_r(int errnum, char *strerrbuf, size_t buflen)
{
if (errnum < 1 || errnum >= sys_nerr) {
errstr(errnum, strerrbuf, buflen);
return (EINVAL);
}
if (strlcpy(strerrbuf, sys_errlist[errnum], buflen) >= buflen)
return (ERANGE);
return (0);
}
char *
strerror(int num)
{
static char ebuf[EBUFSIZE];
if (num > 0 && num < sys_nerr)
return ((char *)sys_errlist[num]);
errno = EINVAL;
errstr(num, ebuf, sizeof(ebuf));
return (ebuf);
}