xref: /netbsd-src/lib/libc/time/asctime.c (revision fdecd6a253f999ae92b139670d9e15cc9df4497c)
1 /*	$NetBSD: asctime.c,v 1.5 1997/06/18 01:12:40 jtc Exp $	*/
2 
3 /*
4 ** This file is in the public domain, so clarified as of
5 ** 1996-06-05 by Arthur David Olson (arthur_david_olson@nih.gov).
6 */
7 
8 #ifndef lint
9 #ifndef NOID
10 static char	elsieid[] = "@(#)asctime.c	7.8";
11 #endif /* !defined NOID */
12 #endif /* !defined lint */
13 
14 /*LINTLIBRARY*/
15 
16 #include "private.h"
17 #include "tzfile.h"
18 
19 /*
20 ** A la X3J11, with core dump avoidance.
21 */
22 
23 char *
24 asctime(timeptr)
25 register const struct tm *	timeptr;
26 {
27 	static const char	wday_name[][3] = {
28 		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
29 	};
30 	static const char	mon_name[][3] = {
31 		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
32 		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
33 	};
34 	/*
35 	** Big enough for something such as
36 	** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
37 	** (two three-character abbreviations, five strings denoting integers,
38 	** three explicit spaces, two explicit colons, a newline,
39 	** and a trailing ASCII nul).
40 	*/
41 	static char		result[3 * 2 + 5 * INT_STRLEN_MAXIMUM(int) +
42 					3 + 2 + 1 + 1];
43 	register const char *	wn;
44 	register const char *	mn;
45 
46 	if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
47 		wn = "???";
48 	else	wn = wday_name[timeptr->tm_wday];
49 	if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
50 		mn = "???";
51 	else	mn = mon_name[timeptr->tm_mon];
52 	/*
53 	** The X3J11-suggested format is
54 	**	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d %d\n"
55 	** Since the .2 in 02.2d is ignored, we drop it.
56 	*/
57 	(void)snprintf(result, sizeof result,"%.3s %.3s%3d %02d:%02d:%02d %d\n",
58 		wn, mn,
59 		timeptr->tm_mday, timeptr->tm_hour,
60 		timeptr->tm_min, timeptr->tm_sec,
61 		TM_YEAR_BASE + timeptr->tm_year);
62 	return result;
63 }
64