cosmopolitan/libc/time/asctime.c
Justine Tunney ead3fc2b31 Fix Landlock Make so it can read pattern rule vars
It turned out that specifying all SRCS and INCS as dependencies on the
pattern rules for all headers, caused `make` memory usage to skyrocket
from 40mb ot 160mb. This change also reduces the build graph another 4%.
2022-08-13 17:23:05 -07:00

117 lines
4.1 KiB
C

#include "libc/fmt/fmt.h"
#include "libc/str/str.h"
#include "libc/time/struct/tm.h"
#include "libc/time/time.h"
#include "libc/time/tz.internal.h"
#include "third_party/python/Include/object.h"
// clang-format off
/* asctime and asctime_r a la POSIX and ISO C, except pad years before 1000. */
/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/
/*
** Avoid the temptation to punt entirely to strftime;
** the output of strftime is supposed to be locale specific
** whereas the output of asctime is supposed to be constant.
*/
/*
** Some systems only handle "%.2d"; others only handle "%02d";
** "%02.2d" makes (most) everybody happy.
** At least some versions of gcc warn about the %02.2d;
** we conditionalize below to avoid the warning.
*/
/*
** All years associated with 32-bit time_t values are exactly four digits long;
** some years associated with 64-bit time_t values are not.
** Vintage programs are coded for years that are always four digits long
** and may assume that the newline always lands in the same place.
** For years that are less than four digits, we pad the output with
** leading zeroes to get the newline in the traditional place.
** The -4 ensures that we get four characters of output even if
** we call a strftime variant that produces fewer characters for some years.
** The ISO C and POSIX standards prohibit padding the year,
** but many implementations pad anyway; most likely the standards are buggy.
*/
#ifdef __GNUC__
#define ASCTIME_FMT "%s %s%3d %2.2d:%2.2d:%2.2d %-4s\n"
#else /* !defined __GNUC__ */
#define ASCTIME_FMT "%s %s%3d %02.2d:%02.2d:%02.2d %-4s\n"
#endif /* !defined __GNUC__ */
/*
** For years that are more than four digits we put extra spaces before the year
** so that code trying to overwrite the newline won't end up overwriting
** a digit within a year and truncating the year (operating on the assumption
** that no output is better than wrong output).
*/
#ifdef __GNUC__
#define ASCTIME_FMT_B "%s %s%3d %2.2d:%2.2d:%2.2d %s\n"
#else /* !defined __GNUC__ */
#define ASCTIME_FMT_B "%s %s%3d %02.2d:%02.2d:%02.2d %s\n"
#endif /* !defined __GNUC__ */
#define STD_ASCTIME_BUF_SIZE 26
/*
** Big enough for something such as
** ??? ???-2147483648 -2147483648:-2147483648:-2147483648 -2147483648\n
** (two three-character abbreviations, five strings denoting integers,
** seven explicit spaces, two explicit colons, a newline,
** and a trailing NUL byte).
** The values above are for systems where an int is 32 bits and are provided
** as an example; the define below calculates the maximum for the system at
** hand.
*/
#define MAX_ASCTIME_BUF_SIZE (2*3+5*INT_STRLEN_MAXIMUM(int)+7+2+1+1)
static char buf_asctime[MAX_ASCTIME_BUF_SIZE];
char *
asctime_r(register const struct tm *timeptr, char *buf)
{
register const char * wn;
register const char * mn;
char year[INT_STRLEN_MAXIMUM(int) + 2];
char result[MAX_ASCTIME_BUF_SIZE];
if (timeptr == NULL) {
errno = EINVAL;
return strcpy(buf, "??? ??? ?? ??:??:?? ????\n");
}
if (timeptr->tm_wday < 0 || timeptr->tm_wday >= DAYSPERWEEK)
wn = "???";
else wn = kWeekdayNameShort[timeptr->tm_wday];
if (timeptr->tm_mon < 0 || timeptr->tm_mon >= MONSPERYEAR)
mn = "???";
else mn = kMonthNameShort[timeptr->tm_mon];
/*
** Use strftime's %Y to generate the year, to avoid overflow problems
** when computing timeptr->tm_year + TM_YEAR_BASE.
** Assume that strftime is unaffected by other out-of-range members
** (e.g., timeptr->tm_mday) when processing "%Y".
*/
strftime(year, sizeof year, "%Y", timeptr);
/*
** We avoid using snprintf since it's not available on all systems.
*/
(sprintf)(result,
((strlen(year) <= 4) ? ASCTIME_FMT : ASCTIME_FMT_B),
wn, mn,
timeptr->tm_mday, timeptr->tm_hour,
timeptr->tm_min, timeptr->tm_sec,
year);
if (strlen(result) < STD_ASCTIME_BUF_SIZE || buf == buf_asctime)
return strcpy(buf, result);
else {
errno = EOVERFLOW;
return NULL;
}
}
char *
asctime(register const struct tm *timeptr)
{
return asctime_r(timeptr, buf_asctime);
}