Asctime.c
Olson, Arthur David (NIH/NCI)
olsona at dc37a.nci.nih.gov
Tue Jul 20 14:36:33 UTC 2004
At the end of this message is a revised version of asctime.c.
There are a couple of standard-related matters.
1. The POSIX standard calls for a struct tm that includes an "int tm_year"
member. If time_t is 64 bits and int is 32 bits, tm_year won't be able to
represent all the years associated with time_t values. Should the standard
address this issue?
2. The standard reads...
The asctime_r() function shall convert the broken-down time in the
structure pointed to by tm into a string (of the same form as that
returned by asctime()) that is placed in the user-supplied buffer
pointed to by buf (which shall contain at least 26 bytes) and then
return buf.
...but a 26-byte buffer won't be adequate if a five-digit (or more) year is
involved.
Should the standard address this issue? Should "asctime_r" assume that the
fed-in buffer is at most 26 bytes and avoid overflowing it?
--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 7.11";
#endif /* !defined NOID */
#endif /* !defined lint */
/*LINTLIBRARY*/
#include "private.h"
#include "tzfile.h"
/*
** 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;
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"
** Use "%02d", as it is a bit more portable than "%.2d".
** Drop each .3 since they're superfluous given how we set wn and
mn.
*/
(void) sprintf(buf, "%s %s%3d %02d:%02d:%02d %ld\n",
wn, mn,
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
timeptr->tm_year + (long) TM_YEAR_BASE);
return buf;
}
/*
** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition,
** with core dump avoidance.
*/
char *
asctime(timeptr)
register const struct tm * timeptr;
{
/*
** 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).
*/
static char result[3 * 2 + 5 * INT_STRLEN_MAXIMUM(int) +
3 + 2 + 1 + 1];
return asctime_r(timeptr, result);
}
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