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glibc/time/strftime.c

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/* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifdef _LIBC
# define HAVE_LIMITS_H 1
# define HAVE_MBLEN 1
# define HAVE_TM_ZONE 1
# define STDC_HEADERS 1
# include <ansidecl.h>
# include "../locale/localeinfo.h"
#endif
#include <stdio.h>
#include <sys/types.h> /* Some systems define `time_t' here. */
#ifdef TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
# else
# include <time.h>
# endif
#endif
#if HAVE_MBLEN
# include <ctype.h>
#endif
#if HAVE_LIMITS_H
# include <limits.h>
#endif
#if STDC_HEADERS
# include <stddef.h>
# include <stdlib.h>
# include <string.h>
#else
# define memcpy(d, s, n) bcopy (s, d, n)
#endif
#ifndef __P
#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
#define __P(args) args
#else
#define __P(args) ()
#endif /* GCC. */
#endif /* Not __P. */
#ifndef PTR
#ifdef __STDC__
#define PTR void *
#else
#define PTR char *
#endif
#endif
static unsigned int week __P((const struct tm *const, int, int));
#define add(n, f) \
do \
{ \
i += (n); \
if (i >= maxsize) \
return 0; \
else \
if (p) \
{ \
f; \
p += (n); \
} \
} while (0)
#define cpy(n, s) add((n), memcpy((PTR) p, (PTR) (s), (n)))
#ifdef _LIBC
#define fmt(n, args) add((n), if (sprintf args != (n)) return 0)
#else
#define fmt(n, args) add((n), sprintf args; if (strlen (p) != (n)) return 0)
#endif
/* Return the week in the year specified by TP,
with weeks starting on STARTING_DAY. */
#ifdef __GNUC__
inline
#endif
static unsigned int
week (tp, starting_day, max_preceding)
const struct tm *const tp;
int starting_day;
int max_preceding;
{
int wday, dl, base;
wday = tp->tm_wday - starting_day;
if (wday < 0)
wday += 7;
/* Set DL to the day in the year of the first day of the week
containing the day specified in TP. */
dl = tp->tm_yday - wday;
/* For the computation following ISO 8601:1988 we set the number of
the week containing January 1st to 1 if this week has more than
MAX_PRECEDING days in the new year. For ISO 8601 this number is
3, for the other representation it is 7 (i.e., not to be
fulfilled). */
base = ((dl + 7) % 7) > max_preceding ? 1 : 0;
/* If DL is negative we compute the result as 0 unless we have to
compute it according ISO 8601. In this case we have to return 53
or 1 if the week containing January 1st has less than 4 days in
the new year or not. If DL is not negative we calculate the
number of complete weeks for our week (DL / 7) plus 1 (because
only for DL < 0 we are in week 0/53 and plus the number of the
first week computed in the last step. */
return dl < 0 ? (dl < -max_preceding ? 53 : base)
: base + 1 + dl / 7;
}
#ifndef _NL_CURRENT
static char const weekday_name[][10] =
{
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"
};
static char const month_name[][10] =
{
"January", "February", "March", "April", "May", "June",
"July", "August", "September", "October", "November", "December"
};
#endif
/* Write information from TP into S according to the format
string FORMAT, writing no more that MAXSIZE characters
(including the terminating '\0') and returning number of
characters written. If S is NULL, nothing will be written
anywhere, so to determine how many characters would be
written, use NULL for S and (size_t) UINT_MAX for MAXSIZE. */
size_t
strftime (s, maxsize, format, tp)
char *s;
size_t maxsize;
const char *format;
register const struct tm *tp;
{
int hour12 = tp->tm_hour;
#ifdef _NL_CURRENT
const char *const a_wkday = _NL_CURRENT (LC_TIME, ABDAY_1 + tp->tm_wday);
const char *const f_wkday = _NL_CURRENT (LC_TIME, DAY_1 + tp->tm_wday);
const char *const a_month = _NL_CURRENT (LC_TIME, ABMON_1 + tp->tm_mon);
const char *const f_month = _NL_CURRENT (LC_TIME, MON_1 + tp->tm_mon);
const char *const ampm = _NL_CURRENT (LC_TIME,
hour12 > 11 ? PM_STR : AM_STR);
size_t aw_len = strlen(a_wkday);
size_t am_len = strlen(a_month);
size_t ap_len = strlen (ampm);
#else
const char *const f_wkday = weekday_name[tp->tm_wday];
const char *const f_month = month_name[tp->tm_mon];
const char *const a_wkday = f_wkday;
const char *const a_month = f_month;
const char *const ampm = "AMPM" + 2 * (hour12 > 11);
size_t aw_len = 3;
size_t am_len = 3;
size_t ap_len = 2;
#endif
size_t wkday_len = strlen(f_wkday);
size_t month_len = strlen(f_month);
const unsigned int y_week0 = week (tp, 0, 7);
const unsigned int y_week1 = week (tp, 1, 7);
const unsigned int y_week2 = week (tp, 1, 3);
const char *zone;
size_t zonelen;
register size_t i = 0;
register char *p = s;
register const char *f;
char number_fmt[5];
/* Initialize the buffer we will use for the sprintf format for numbers. */
number_fmt[0] = '%';
zone = 0;
#if HAVE_TM_ZONE
zone = (const char *) tp->tm_zone;
#endif
#if HAVE_TZNAME
if (!(zone && *zone) && tp->tm_isdst >= 0)
zone = tzname[tp->tm_isdst];
#endif
if (!(zone && *zone))
zone = "???";
zonelen = strlen (zone);
if (hour12 > 12)
hour12 -= 12;
else
if (hour12 == 0) hour12 = 12;
for (f = format; *f != '\0'; ++f)
{
enum { pad_zero, pad_space, pad_none } pad; /* Padding for number. */
unsigned int maxdigits; /* Max digits for numeric format. */
unsigned int number_value; /* Numeric value to be printed. */
const char *subfmt;
#if HAVE_MBLEN
if (!isascii(*f))
{
/* Non-ASCII, may be a multibyte. */
int len = mblen(f, strlen(f));
if (len > 0)
{
cpy(len, f);
continue;
}
}
#endif
if (*f != '%')
{
add(1, *p = *f);
continue;
}
/* Check for flags that can modify a number format. */
++f;
switch (*f)
{
case '_':
pad = pad_space;
++f;
break;
case '-':
pad = pad_none;
++f;
break;
default:
pad = pad_zero;
break;
}
/* Now do the specified format. */
switch (*f)
{
case '\0':
case '%':
add(1, *p = *f);
break;
case 'a':
cpy(aw_len, a_wkday);
break;
case 'A':
cpy(wkday_len, f_wkday);
break;
case 'b':
case 'h': /* GNU extension. */
cpy(am_len, a_month);
break;
case 'B':
cpy(month_len, f_month);
break;
case 'c':
#ifdef _NL_CURRENT
subfmt = _NL_CURRENT (LC_TIME, D_T_FMT);
#else
subfmt = "%a %b %d %H:%M:%S %Z %Y";
#endif
subformat:
{
size_t len = strftime (p, maxsize - i, subfmt, tp);
if (len == 0 && *subfmt)
return 0;
add(len, );
}
break;
#define DO_NUMBER(digits, value) \
maxdigits = digits; number_value = value; goto do_number
#define DO_NUMBER_SPACEPAD(digits, value) \
maxdigits = digits; number_value = value; goto do_number_spacepad
case 'C':
DO_NUMBER (2, (1900 + tp->tm_year) / 100);
case 'x':
#ifdef _NL_CURRENT
subfmt = _NL_CURRENT (LC_TIME, D_FMT);
goto subformat;
#endif
/* Fall through. */
case 'D': /* GNU extension. */
subfmt = "%m/%d/%y";
goto subformat;
case 'd':
DO_NUMBER (2, tp->tm_mday);
case 'e': /* GNU extension: %d, but blank-padded. */
DO_NUMBER_SPACEPAD (2, tp->tm_mday);
/* All numeric formats set MAXDIGITS and NUMBER_VALUE and then
jump to one of these two labels. */
do_number_spacepad:
/* Force `_' flag. */
pad = pad_space;
do_number:
{
/* Format the number according to the PAD flag. */
register char *nf = &number_fmt[1];
int printed;
switch (pad)
{
case pad_zero:
*nf++ = '0';
case pad_space:
*nf++ = '0' + maxdigits;
case pad_none:
*nf++ = 'u';
*nf = '\0';
}
#ifdef _LIBC
add (maxdigits, printed = sprintf (p, number_fmt, number_value));
#else
add (maxdigits, sprintf (p, number_fmt, number_value);
printed = strlen (p));
#endif
/* Back up if fewer than MAXDIGITS chars written for pad_none. */
p -= maxdigits - printed;
i -= maxdigits - printed;
break;
}
case 'H':
DO_NUMBER (2, tp->tm_hour);
case 'I':
DO_NUMBER (2, hour12);
case 'k': /* GNU extension. */
DO_NUMBER_SPACEPAD (2, tp->tm_hour);
case 'l': /* GNU extension. */
DO_NUMBER_SPACEPAD (2, hour12);
case 'j':
DO_NUMBER (3, 1 + tp->tm_yday);
case 'M':
DO_NUMBER (2, tp->tm_min);
case 'm':
DO_NUMBER (2, tp->tm_mon + 1);
case 'n': /* GNU extension. */
add (1, *p = '\n');
break;
case 'p':
cpy(ap_len, ampm);
break;
case 'R': /* GNU extension. */
subfmt = "%H:%M";
goto subformat;
case 'r': /* GNU extension. */
subfmt = "%I:%M:%S %p";
goto subformat;
case 'S':
DO_NUMBER (2, tp->tm_sec);
case 'X':
#ifdef _NL_CURRENT
subfmt = _NL_CURRENT (LC_TIME, T_FMT);
goto subformat;
#endif
/* Fall through. */
case 'T': /* GNU extenstion. */
subfmt = "%H:%M:%S";
goto subformat;
case 't': /* GNU extenstion. */
add (1, *p = '\t');
break;
case 'U':
DO_NUMBER (2, y_week0);
case 'V':
DO_NUMBER (2, y_week2);
case 'W':
DO_NUMBER (2, y_week1);
case 'w':
DO_NUMBER (2, tp->tm_wday);
case 'Y':
DO_NUMBER (4, 1900 + tp->tm_year);
case 'y':
DO_NUMBER (2, tp->tm_year % 100);
case 'Z':
cpy(zonelen, zone);
break;
default:
/* Bad format. */
break;
}
}
if (p)
*p = '\0';
return i;
}
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