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