asctime.c
Olson, Arthur David (NIH/NCI)
olsona at dc37a.nci.nih.gov
Tue Jul 27 14:53:36 UTC 2004
Thanks to all for feedback on asctime.c. The version below uses %02.2d for
universality, uses %4ld for years to avoid problems if a year isn't four
digits long, and avoids the use of snprintf (which isn't available on some
systems). There are comments on all these changes. Is it soup yet?
--ado
/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson (arthur_david_olson at nih.gov).
*/
#ifndef lint
#ifndef NOID
static char elsieid[] = "@(#)asctime.c 7.15";
#endif /* !defined NOID */
#endif /* !defined lint */
/*LINTLIBRARY*/
#include "private.h"
#include "tzfile.h"
#define STANDARD_BUFFER_SIZE 26
/*
** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
*/
char *
asctime_r(timeptr, buf)
register const struct tm * timeptr;
char * buf;
{
static const char wday_name[][3] = {
"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
};
static const char mon_name[][3] = {
"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
};
register const char * wn;
register const char * mn;
/*
** Big enough for something such as
** ??? ???-2147483648 -2147483648:-2147483648:-2147483648
-2147483648\n
** (two three-character abbreviations, five strings denoting
integers,
** three explicit spaces, two explicit colons, a newline,
** and a trailing ASCII nul).
*/
char result[2 * 3 + 5 * INT_STRLEN_MAXIMUM(int) +
3 + 2 + 1 + 1];
if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
wn = "???";
else wn = wday_name[timeptr->tm_wday];
if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
mn = "???";
else mn = mon_name[timeptr->tm_mon];
/*
** The format used in the (2004) standard is
** "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n"
** Some systems only handle "%.2d"; others only handle "%02d";
** "%02.2d" makes (most) everybody happy.
** All years associated with 32-bit time_t values are exactly
** four digits long; some years associated with 64-bit time_t
** values are not four digits long so we throw in the 4 below.
*/
/*
** We avoid using snprintf since it's not available on all systems.
*/
(void) sprintf(result, "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %4ld\n",
wn, mn,
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
timeptr->tm_year + (long) TM_YEAR_BASE);
if (strlen(result) >= STANDARD_BUFFER_SIZE) {
errno = EOVERFLOW;
return NULL;
} else {
(void) strcpy(buf, result);
return buf;
}
}
/*
** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
*/
char *
asctime(timeptr)
register const struct tm * timeptr;
{
static char result[STANDARD_BUFFER_SIZE];
return asctime_r(timeptr, result);
}
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