New, improved, more Posix-compliant strerror_r implementation,
complete with documentation. Reviewed by: mike@ gad@ MFC after: 1 week
This commit is contained in:
Wes Peters
parent
5a31fd21e9
commit
f61a2ede84
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=87434
@ -81,16 +81,7 @@ function renders the same result into
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.Fa strerrbuf
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for a maximum of
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.Fa buflen
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characters and returns 0 upon success. If insufficient
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storage is provided in
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.Fa strerrbuf
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(as specified in
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.Fa buflen )
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to contain the error string,
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.Er ERANGE
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is returned and the string in
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.Fa strerrbuf
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may not be null-terminated.
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characters and returns 0 upon success.
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.Pp
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The
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.Fn perror
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@ -114,9 +105,25 @@ otherwise, only the error message string is printed.
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If
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.Fa errnum
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is not a recognized error number,
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the error message string will contain
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.Fn strerror
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returns an error message string containing
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.Dq Li "Unknown error:\ "
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followed by the error number in decimal.
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followed by the error number in decimal, while
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.Fn strerror_r
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returns
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.Er EINVAL .
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.Pp
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If insufficient storage is provided in
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.Fa strerrbuf
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(as specified in
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.Fa buflen )
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to contain the error string,
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.Fn strerror_r
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returns
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.Er ERANGE
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and the contents of
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.Fa strerrbuf
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are indeterminate.
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.Pp
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The message strings can be accessed directly using the external
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array
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@ -41,88 +41,87 @@ __FBSDID("$FreeBSD$");
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#include <string.h>
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#include <errno.h>
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int
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strerror_r(int errnum, char *strerrbuf, size_t buflen)
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{
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#define UPREFIX "Unknown error: "
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unsigned int uerr;
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char *p, *t;
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char tmp[40]; /* 64-bit number + slop */
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int len;
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int len;
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uerr = errnum; /* convert to unsigned */
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if (uerr < sys_nerr) {
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len = strlcpy(strerrbuf, (char *)sys_errlist[uerr], buflen);
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return (len <= buflen) ? 0 : ERANGE;
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if ((errnum > 0) && (errnum < sys_nerr)) {
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len = strlcpy(strerrbuf, (char *)sys_errlist[errnum], buflen);
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return ((len <= buflen) ? 0 : ERANGE);
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}
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/* Print unknown errno by hand so we don't link to stdio(3). */
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t = tmp;
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if (errnum < 0)
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uerr = -uerr;
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do {
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*t++ = "0123456789"[uerr % 10];
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} while (uerr /= 10);
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if (errnum < 0)
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*t++ = '-';
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strlcpy(strerrbuf, UPREFIX, buflen);
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for (p = strerrbuf + sizeof(UPREFIX) - 1; p < strerrbuf + buflen; ) {
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*p++ = *--t;
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if (t <= tmp)
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break;
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}
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if (p < strerrbuf + buflen) {
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*p = '\0';
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return 0;
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}
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return ERANGE;
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return (EINVAL);
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}
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/*
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* NOTE: the following length should be enough to hold the longest defined
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* error message in sys_errlist, defined in ../gen/errlst.c. This is a WAG
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* that is better than the previous value.
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*/
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#define ERR_LEN 64
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char *
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strerror(num)
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int num;
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int num;
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{
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unsigned int uerr;
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static char ebuf[ERR_LEN];
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char *p, *t;
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unsigned int uerr;
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static char const unknown_prefix[] = "Unknown error: ";
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uerr = num; /* convert to unsigned */
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if (uerr < sys_nerr)
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return (char *)sys_errlist[uerr];
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/*
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* Define a buffer size big enough to describe a 64-bit
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* number in ASCII decimal (19), with optional leading sign
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* (+1) and trailing NUL (+1).
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*/
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# define NUMLEN 21
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# define EBUFLEN (sizeof unknown_prefix + NUMLEN)
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char tmp[NUMLEN]; /* temporary number */
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static char ebuf[EBUFLEN]; /* error message */
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/* strerror can't fail so handle truncation semi-elegantly */
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if (strerror_r(num, ebuf, (size_t) ERR_LEN) != 0)
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ebuf[ERR_LEN - 1] = '\0';
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if ((num > 0) && (num < sys_nerr))
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return ((char *)sys_errlist[num]);
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return ebuf;
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/*
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* Print unknown errno by hand so we don't link to stdio(3).
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* This collects the ASCII digits in reverse order.
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*/
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uerr = (num > 0) ? num : -num;
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t = tmp;
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do {
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*t++ = "0123456789"[uerr % 10];
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} while (uerr /= 10);
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if (num < 0)
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*t++ = '-';
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/*
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* Copy the "unknown" message and the number into the caller
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* supplied buffer, inverting the number string.
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*/
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strcpy(ebuf, unknown_prefix);
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for (p = ebuf + sizeof unknown_prefix - 1; t >= tmp; )
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*p++ = *--t;
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*p = '\0';
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return (ebuf);
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}
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#ifdef STANDALONE_TEST
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#include <limits.h>
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main()
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{
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char mybuf[64];
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int ret;
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char mybuf[64];
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int ret;
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printf("strerror(47) yeilds: %s\n", strerror(47));
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printf("strerror(437) yeilds: %s\n", strerror(437));
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printf("strerror(LONG_MAX) yeilds: %s\n", strerror(LONG_MAX));
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printf("strerror(LONG_MIN) yeilds: %s\n", strerror(LONG_MIN));
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printf("strerror(ULONG_MAX) yeilds: %s\n", strerror(ULONG_MAX));
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memset(mybuf, '*', 63); mybuf[63] = '\0';
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strerror_r(11, mybuf, 64);
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printf("strerror_r(11) yeilds: %s\n", mybuf);
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strerror_r(1234, mybuf, 64);
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printf("strerror_r(1234) yeilds: %s\n", mybuf);
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memset(mybuf, '*', 63);
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ret = strerror_r(4321, mybuf, 16);
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memset(mybuf, '*', 63); mybuf[63] = '\0';
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ret = strerror_r(1234, mybuf, 64);
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printf("strerror_r(1234) returns %d (%s)\n", ret, mybuf);
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memset(mybuf, '*', 63); mybuf[63] = '\0';
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ret = strerror_r(1, mybuf, 10);
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printf("strerror_r on short buffer returns %d (%s)\n", ret, mybuf);
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}
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#endif
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