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New, improved, more Posix-compliant strerror_r implementation,

Browse Source 
complete with documentation.

Reviewed by:	mike@ gad@
MFC after:	1 week
This commit is contained in:
Wes Peters 2001-12-06 04:53:31 +00:00
parent 5a31fd21e9
commit f61a2ede84
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=87434
2 changed files with 78 additions and 72 deletions
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31
lib/libc/string/strerror.3
View File

@ -81,16 +81,7 @@ function renders the same result into
.Fa strerrbuf
for a maximum of
.Fa buflen
characters and returns 0 upon success. If insufficient
storage is provided in
.Fa strerrbuf
(as specified in
.Fa buflen )
to contain the error string,
.Er ERANGE
is returned and the string in
.Fa strerrbuf
may not be null-terminated.
characters and returns 0 upon success.
.Pp
The
.Fn perror
@ -114,9 +105,25 @@ otherwise, only the error message string is printed.
If
.Fa errnum
is not a recognized error number,
the error message string will contain
.Fn strerror
returns an error message string containing
.Dq Li "Unknown error:\ "
followed by the error number in decimal.
followed by the error number in decimal, while
.Fn strerror_r
returns
.Er EINVAL .
.Pp
If insufficient storage is provided in
.Fa strerrbuf
(as specified in
.Fa buflen )
to contain the error string,
.Fn strerror_r
returns
.Er ERANGE
and the contents of
.Fa strerrbuf
are indeterminate.
.Pp
The message strings can be accessed directly using the external
array

119
lib/libc/string/strerror.c
View File

@ -41,88 +41,87 @@ __FBSDID("$FreeBSD$");
#include <string.h>
#include <errno.h>
int
strerror_r(int errnum, char *strerrbuf, size_t buflen)
{
#define UPREFIX "Unknown error: "
unsigned int uerr;
char *p, *t;
char tmp[40]; /* 64-bit number + slop */
int len;
int len;
uerr = errnum; /* convert to unsigned */
if (uerr < sys_nerr) {
len = strlcpy(strerrbuf, (char *)sys_errlist[uerr], buflen);
return (len <= buflen) ? 0 : ERANGE;
if ((errnum > 0) && (errnum < sys_nerr)) {
len = strlcpy(strerrbuf, (char *)sys_errlist[errnum], buflen);
return ((len <= buflen) ? 0 : ERANGE);
}
/* Print unknown errno by hand so we don't link to stdio(3). */
t = tmp;
if (errnum < 0)
uerr = -uerr;
do {
*t++ = "0123456789"[uerr % 10];
} while (uerr /= 10);
if (errnum < 0)
*t++ = '-';
strlcpy(strerrbuf, UPREFIX, buflen);
for (p = strerrbuf + sizeof(UPREFIX) - 1; p < strerrbuf + buflen; ) {
*p++ = *--t;
if (t <= tmp)
break;
}
if (p < strerrbuf + buflen) {
*p = '\0';
return 0;
}
return ERANGE;
return (EINVAL);
}
/*
* NOTE: the following length should be enough to hold the longest defined
* error message in sys_errlist, defined in ../gen/errlst.c. This is a WAG
* that is better than the previous value.
*/
#define ERR_LEN 64
char *
strerror(num)
int num;
int num;
{
unsigned int uerr;
static char ebuf[ERR_LEN];
char *p, *t;
unsigned int uerr;
static char const unknown_prefix[] = "Unknown error: ";
uerr = num; /* convert to unsigned */
if (uerr < sys_nerr)
return (char *)sys_errlist[uerr];
/*
* Define a buffer size big enough to describe a 64-bit
* number in ASCII decimal (19), with optional leading sign
* (+1) and trailing NUL (+1).
*/
# define NUMLEN 21
# define EBUFLEN (sizeof unknown_prefix + NUMLEN)
char tmp[NUMLEN]; /* temporary number */
static char ebuf[EBUFLEN]; /* error message */
/* strerror can't fail so handle truncation semi-elegantly */
if (strerror_r(num, ebuf, (size_t) ERR_LEN) != 0)
ebuf[ERR_LEN - 1] = '\0';
if ((num > 0) && (num < sys_nerr))
return ((char *)sys_errlist[num]);
return ebuf;
/*
* Print unknown errno by hand so we don't link to stdio(3).
* This collects the ASCII digits in reverse order.
*/
uerr = (num > 0) ? num : -num;
t = tmp;
do {
*t++ = "0123456789"[uerr % 10];
} while (uerr /= 10);
if (num < 0)
*t++ = '-';
/*
* Copy the "unknown" message and the number into the caller
* supplied buffer, inverting the number string.
*/
strcpy(ebuf, unknown_prefix);
for (p = ebuf + sizeof unknown_prefix - 1; t >= tmp; )
*p++ = *--t;
*p = '\0';
return (ebuf);
}
#ifdef STANDALONE_TEST
#include <limits.h>
main()
{
char mybuf[64];
int ret;
char mybuf[64];
int ret;
printf("strerror(47) yeilds: %s\n", strerror(47));
printf("strerror(437) yeilds: %s\n", strerror(437));
printf("strerror(LONG_MAX) yeilds: %s\n", strerror(LONG_MAX));
printf("strerror(LONG_MIN) yeilds: %s\n", strerror(LONG_MIN));
printf("strerror(ULONG_MAX) yeilds: %s\n", strerror(ULONG_MAX));
memset(mybuf, '*', 63); mybuf[63] = '\0';
strerror_r(11, mybuf, 64);
printf("strerror_r(11) yeilds: %s\n", mybuf);
strerror_r(1234, mybuf, 64);
printf("strerror_r(1234) yeilds: %s\n", mybuf);
memset(mybuf, '*', 63);
ret = strerror_r(4321, mybuf, 16);
memset(mybuf, '*', 63); mybuf[63] = '\0';
ret = strerror_r(1234, mybuf, 64);
printf("strerror_r(1234) returns %d (%s)\n", ret, mybuf);
memset(mybuf, '*', 63); mybuf[63] = '\0';
ret = strerror_r(1, mybuf, 10);
printf("strerror_r on short buffer returns %d (%s)\n", ret, mybuf);
}
#endif