Here's my latest effort at asctime.c. In this version, asctime itself never
returns NULL which I trust makes folks happy.
Given kre's points about avoiding breaking existing code, the format of what
asctime returns is not always standard conforming which I trust makes some
folks unhappy.
Feedback welcome.
--ado
/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson (arthur_david_olson(a)nih.gov)
*/
#ifndef lint
#ifndef NOID
static char elsieid[] = "@(#)asctime.c 7.16";
#endif /* !defined NOID */
#endif /* !defined lint */
/*LINTLIBRARY*/
#include "private.h"
#include "tzfile.h"
#if STRICTLY_STANDARD_ASCTIME
#define ASCTIME_FMT "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n"
#define ASCTIME_FMT_B ASCTIME_FMT
#else /* !STRICTLY_STANDARD_ASCTIME */
/*
** 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.
** Vintage programs are coded for years that are always four digits long
** and may assume that the newline always lands in the same place.
** For years that are less than four digits, we pad the output with
** spaces before the newline to get the newline in the traditional place.
*/
#define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4ld\n"
/*
** For years that are more than four digits we put extra spaces before the
year
** so that code trying to overwrite the newline won't end up overwriting
** a digit within a year and truncating the year (operating on the
assumption
** that no output is better than wrong output).
*/
#define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %ld\n"
#endif /* !STRICTLY_STANDARD_ASCTIME */
#define STD_ASCTIME_BUF_SIZE 26
/*
** Big enough for something such as
** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
** (two three-character abbreviations, five strings denoting integers,
** seven explicit spaces, two explicit colons, a newline,
** and a trailing ASCII nul).
** The values above are for systems where an int is 32 bits and are provided
** as an example; the define below calculates the maximum for system at
hand.
*/
#define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
static char buf_asctime[MAX_ASCTIME_BUF_SIZE];
/*
** 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;
long year;
char result[MAX_ASCTIME_BUF_SIZE];
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];
year = timeptr->tm_year + (long) TM_YEAR_BASE;
/*
** We avoid using snprintf since it's not available on all systems.
*/
(void) sprintf(result,
((year >= -999 && year <= 9999) ? ASCTIME_FMT :
ASCTIME_FMT_B),
wn, mn,
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
year);
if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) {
(void) strcpy(buf, result);
return buf;
} else {
errno = EOVERFLOW;
return NULL;
}
}
/*
** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
*/
char *
asctime(timeptr)
register const struct tm * timeptr;
{
return asctime_r(timeptr, buf_asctime);
}
