1/*
2** This file is in the public domain, so clarified as of
3** 1996-06-05 by Arthur David Olson.
4*/
5
6/*
7** Avoid the temptation to punt entirely to strftime;
8** the output of strftime is supposed to be locale specific
9** whereas the output of asctime is supposed to be constant.
10*/
11
12#include <sys/cdefs.h>
13#ifndef lint
14#ifndef NOID
15static char	elsieid[] __unused = "@(#)asctime.c	8.5";
16#endif /* !defined NOID */
17#endif /* !defined lint */
18__FBSDID("$FreeBSD$");
19
20/*LINTLIBRARY*/
21
22#include "namespace.h"
23#include "private.h"
24#include "un-namespace.h"
25#include "tzfile.h"
26
27/*
28** Some systems only handle "%.2d"; others only handle "%02d";
29** "%02.2d" makes (most) everybody happy.
30** At least some versions of gcc warn about the %02.2d;
31** we conditionalize below to avoid the warning.
32*/
33/*
34** All years associated with 32-bit time_t values are exactly four digits long;
35** some years associated with 64-bit time_t values are not.
36** Vintage programs are coded for years that are always four digits long
37** and may assume that the newline always lands in the same place.
38** For years that are less than four digits, we pad the output with
39** leading zeroes to get the newline in the traditional place.
40** The -4 ensures that we get four characters of output even if
41** we call a strftime variant that produces fewer characters for some years.
42** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
43** but many implementations pad anyway; most likely the standards are buggy.
44*/
45#ifdef __GNUC__
46#define ASCTIME_FMT	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"
47#else /* !defined __GNUC__ */
48#define ASCTIME_FMT	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
49#endif /* !defined __GNUC__ */
50/*
51** For years that are more than four digits we put extra spaces before the year
52** so that code trying to overwrite the newline won't end up overwriting
53** a digit within a year and truncating the year (operating on the assumption
54** that no output is better than wrong output).
55*/
56#ifdef __GNUC__
57#define ASCTIME_FMT_B	"%.3s %.3s%3d %2.2d:%2.2d:%2.2d     %s\n"
58#else /* !defined __GNUC__ */
59#define ASCTIME_FMT_B	"%.3s %.3s%3d %02.2d:%02.2d:%02.2d     %s\n"
60#endif /* !defined __GNUC__ */
61
62#define STD_ASCTIME_BUF_SIZE	26
63/*
64** Big enough for something such as
65** ??? ???-2147483648 -2147483648:-2147483648:-2147483648     -2147483648\n
66** (two three-character abbreviations, five strings denoting integers,
67** seven explicit spaces, two explicit colons, a newline,
68** and a trailing ASCII nul).
69** The values above are for systems where an int is 32 bits and are provided
70** as an example; the define below calculates the maximum for the system at
71** hand.
72*/
73#define MAX_ASCTIME_BUF_SIZE	(2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
74
75static char	buf_asctime[MAX_ASCTIME_BUF_SIZE];
76
77/*
78** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
79*/
80
81char *
82asctime_r(timeptr, buf)
83const struct tm *	timeptr;
84char *			buf;
85{
86	static const char	wday_name[][3] = {
87		"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
88	};
89	static const char	mon_name[][3] = {
90		"Jan", "Feb", "Mar", "Apr", "May", "Jun",
91		"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
92	};
93	const char *	wn;
94	const char *	mn;
95	char			year[INT_STRLEN_MAXIMUM(int) + 2];
96	char			result[MAX_ASCTIME_BUF_SIZE];
97
98	if (timeptr == NULL) {
99		errno = EINVAL;
100		return strcpy(buf, "??? ??? ?? ??:??:?? ????\n");
101	}
102	if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
103		wn = "???";
104	else	wn = wday_name[timeptr->tm_wday];
105	if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
106		mn = "???";
107	else	mn = mon_name[timeptr->tm_mon];
108	/*
109	** Use strftime's %Y to generate the year, to avoid overflow problems
110	** when computing timeptr->tm_year + TM_YEAR_BASE.
111	** Assume that strftime is unaffected by other out-of-range members
112	** (e.g., timeptr->tm_mday) when processing "%Y".
113	*/
114	(void) strftime(year, sizeof year, "%Y", timeptr);
115	/*
116	** We avoid using snprintf since it's not available on all systems.
117	*/
118	(void) sprintf(result,
119		((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
120		wn, mn,
121		timeptr->tm_mday, timeptr->tm_hour,
122		timeptr->tm_min, timeptr->tm_sec,
123		year);
124	if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime)
125		return strcpy(buf, result);
126	else {
127#ifdef EOVERFLOW
128		errno = EOVERFLOW;
129#else /* !defined EOVERFLOW */
130		errno = EINVAL;
131#endif /* !defined EOVERFLOW */
132		return NULL;
133	}
134}
135
136/*
137** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
138*/
139
140char *
141asctime(timeptr)
142const struct tm *	timeptr;
143{
144	return asctime_r(timeptr, buf_asctime);
145}
146