130 lines
4 KiB
C
130 lines
4 KiB
C
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/*
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** This file is in the public domain, so clarified as of
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** 1996-06-05 by Arthur David Olson.
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*/
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/*
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** Avoid the temptation to punt entirely to strftime;
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** the output of strftime is supposed to be locale specific
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** whereas the output of asctime is supposed to be constant.
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*/
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#ifndef lint
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#ifndef NOID
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static char elsieid[] = "@(#)asctime.c 7.32";
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#endif /* !defined NOID */
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#endif /* !defined lint */
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/*LINTLIBRARY*/
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#include "private.h"
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#include "tzfile.h"
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/*
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** Some systems only handle "%.2d"; others only handle "%02d";
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** "%02.2d" makes (most) everybody happy.
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** At least some versions of gcc warn about the %02.2d; ignore the warning.
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*/
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/*
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** All years associated with 32-bit time_t values are exactly four digits long;
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** some years associated with 64-bit time_t values are not.
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** Vintage programs are coded for years that are always four digits long
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** and may assume that the newline always lands in the same place.
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** For years that are less than four digits, we pad the output with
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** leading zeroes to get the newline in the traditional place.
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** The -4 ensures that we get four characters of output even if
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** we call a strftime variant that produces fewer characters for some years.
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** The ISO C 1999 and POSIX 1003.1-2004 standards prohibit padding the year,
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** but many implementations pad anyway; most likely the standards are buggy.
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*/
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#define ASCTIME_FMT "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %-4s\n"
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/*
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** For years that are more than four digits we put extra spaces before the year
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** so that code trying to overwrite the newline won't end up overwriting
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** a digit within a year and truncating the year (operating on the assumption
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** that no output is better than wrong output).
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*/
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#define ASCTIME_FMT_B "%.3s %.3s%3d %02.2d:%02.2d:%02.2d %s\n"
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#define STD_ASCTIME_BUF_SIZE 26
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/*
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** Big enough for something such as
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** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
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** (two three-character abbreviations, five strings denoting integers,
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** seven explicit spaces, two explicit colons, a newline,
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** and a trailing ASCII nul).
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** The values above are for systems where an int is 32 bits and are provided
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** as an example; the define below calculates the maximum for the system at
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** hand.
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*/
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#define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
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static char buf_asctime[MAX_ASCTIME_BUF_SIZE];
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/*
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** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
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*/
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char *
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asctime_r(timeptr, buf)
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register const struct tm * timeptr;
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char * buf;
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{
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static const char wday_name[][3] = {
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"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
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};
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static const char mon_name[][3] = {
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"Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
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};
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register const char * wn;
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register const char * mn;
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char year[INT_STRLEN_MAXIMUM(int) + 2];
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char result[MAX_ASCTIME_BUF_SIZE];
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if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
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wn = "???";
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else wn = wday_name[timeptr->tm_wday];
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if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
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mn = "???";
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else mn = mon_name[timeptr->tm_mon];
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/*
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** Use strftime's %Y to generate the year, to avoid overflow problems
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** when computing timeptr->tm_year + TM_YEAR_BASE.
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** Assume that strftime is unaffected by other out-of-range members
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** (e.g., timeptr->tm_mday) when processing "%Y".
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*/
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(void) strftime(year, sizeof year, "%Y", timeptr);
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/*
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** We avoid using snprintf since it's not available on all systems.
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*/
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(void) sprintf(result,
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((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
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wn, mn,
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timeptr->tm_mday, timeptr->tm_hour,
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timeptr->tm_min, timeptr->tm_sec,
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year);
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if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime) {
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(void) strcpy(buf, result);
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return buf;
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} else {
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#ifdef EOVERFLOW
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errno = EOVERFLOW;
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#else /* !defined EOVERFLOW */
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errno = EINVAL;
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#endif /* !defined EOVERFLOW */
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return NULL;
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}
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}
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/*
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** A la ISO/IEC 9945-1, ANSI/IEEE Std 1003.1, 2004 Edition.
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*/
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char *
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asctime(timeptr)
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register const struct tm * timeptr;
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{
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return asctime_r(timeptr, buf_asctime);
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}
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