2 ** This file is in the public domain, so clarified as of
3 ** 1996-06-05 by Arthur David Olson.
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.
12 ** $FreeBSD: src/lib/libc/stdtime/asctime.c,v 1.7.6.1 2001/03/05 11:37:20 obrien Exp $
13 ** $DragonFly: src/lib/libc/stdtime/asctime.c,v 1.6 2008/10/19 20:15:58 swildner Exp $
17 #include "namespace.h"
19 #include "un-namespace.h"
23 ** Some systems only handle "%.2d"; others only handle "%02d";
24 ** "%02.2d" makes (most) everybody happy.
25 ** At least some versions of gcc warn about the %02.2d;
26 ** we conditionalize below to avoid the warning.
29 ** All years associated with 32-bit time_t values are exactly four digits long;
30 ** some years associated with 64-bit time_t values are not.
31 ** Vintage programs are coded for years that are always four digits long
32 ** and may assume that the newline always lands in the same place.
33 ** For years that are less than four digits, we pad the output with
34 ** leading zeroes to get the newline in the traditional place.
35 ** The -4 ensures that we get four characters of output even if
36 ** we call a strftime variant that produces fewer characters for some years.
37 ** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
38 ** but many implementations pad anyway; most likely the standards are buggy.
41 #define ASCTIME_FMT "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %-4s\n"
42 #else /* !defined __GNUC__ */
43 #define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
44 #endif /* !defined __GNUC__ */
46 ** For years that are more than four digits we put extra spaces before the year
47 ** so that code trying to overwrite the newline won't end up overwriting
48 ** a digit within a year and truncating the year (operating on the assumption
49 ** that no output is better than wrong output).
52 #define ASCTIME_FMT_B "%.3s %.3s%3d %2.2d:%2.2d:%2.2d %s\n"
53 #else /* !defined __GNUC__ */
54 #define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n"
55 #endif /* !defined __GNUC__ */
57 #define STD_ASCTIME_BUF_SIZE 26
59 ** Big enough for something such as
60 ** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
61 ** (two three-character abbreviations, five strings denoting integers,
62 ** seven explicit spaces, two explicit colons, a newline,
63 ** and a trailing ASCII nul).
64 ** The values above are for systems where an int is 32 bits and are provided
65 ** as an example; the define below calculates the maximum for the system at
68 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
70 static char buf_asctime
[MAX_ASCTIME_BUF_SIZE
];
73 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
78 asctime_r(const struct tm
*timeptr
, char *buf
)
80 static const char wday_name
[][3] = {
81 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
83 static const char mon_name
[][3] = {
84 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
85 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
87 char year
[INT_STRLEN_MAXIMUM(int) + 2];
88 char result
[MAX_ASCTIME_BUF_SIZE
];
92 if (timeptr
->tm_wday
< 0 || timeptr
->tm_wday
>= DAYSPERWEEK
)
94 else wn
= wday_name
[timeptr
->tm_wday
];
95 if (timeptr
->tm_mon
< 0 || timeptr
->tm_mon
>= MONSPERYEAR
)
97 else mn
= mon_name
[timeptr
->tm_mon
];
99 ** Use strftime's %Y to generate the year, to avoid overflow problems
100 ** when computing timeptr->tm_year + TM_YEAR_BASE.
101 ** Assume that strftime is unaffected by other out-of-range members
102 ** (e.g., timeptr->tm_mday) when processing "%Y".
104 strftime(year
, sizeof year
, "%Y", timeptr
);
105 snprintf(result
, sizeof result
,
106 ((strlen(year
) <= 4) ? ASCTIME_FMT
: ASCTIME_FMT_B
),
108 timeptr
->tm_mday
, timeptr
->tm_hour
,
109 timeptr
->tm_min
, timeptr
->tm_sec
,
111 if (strlen(result
) < STD_ASCTIME_BUF_SIZE
|| buf
== buf_asctime
) {
112 (void) strcpy(buf
, result
);
121 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
125 asctime(const struct tm
*timeptr
)
127 return asctime_r(timeptr
, buf_asctime
);