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 #include <sys/cdefs.h>
15 static char elsieid[] __unused = "@(#)asctime.c 8.5";
16 #endif /* !defined NOID */
17 #endif /* !defined lint */
18 __FBSDID("$FreeBSD$");
22 #include "namespace.h"
24 #include "un-namespace.h"
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.
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.
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__ */
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).
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__ */
62 #define STD_ASCTIME_BUF_SIZE 26
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
73 #define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
75 static char buf_asctime[MAX_ASCTIME_BUF_SIZE];
78 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
82 asctime_r(timeptr, buf)
83 const struct tm * timeptr;
86 static const char wday_name[][3] = {
87 "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
89 static const char mon_name[][3] = {
90 "Jan", "Feb", "Mar", "Apr", "May", "Jun",
91 "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
95 char year[INT_STRLEN_MAXIMUM(int) + 2];
96 char result[MAX_ASCTIME_BUF_SIZE];
98 if (timeptr == NULL) {
100 return strcpy(buf, "??? ??? ?? ??:??:?? ????\n");
102 if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
104 else wn = wday_name[timeptr->tm_wday];
105 if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
107 else mn = mon_name[timeptr->tm_mon];
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".
114 (void) strftime(year, sizeof year, "%Y", timeptr);
116 ** We avoid using snprintf since it's not available on all systems.
118 (void) sprintf(result,
119 ((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
121 timeptr->tm_mday, timeptr->tm_hour,
122 timeptr->tm_min, timeptr->tm_sec,
124 if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime)
125 return strcpy(buf, result);
129 #else /* !defined EOVERFLOW */
131 #endif /* !defined EOVERFLOW */
137 ** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
142 const struct tm * timeptr;
144 return asctime_r(timeptr, buf_asctime);