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newlib-cygwin/newlib/libc/time/strftime.c

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/*
* strftime.c
* Original Author: G. Haley
* Additions from: Eric Blake
*
* Places characters into the array pointed to by s as controlled by the string
* pointed to by format. If the total number of resulting characters including
* the terminating null character is not more than maxsize, returns the number
* of characters placed into the array pointed to by s (not including the
* terminating null character); otherwise zero is returned and the contents of
* the array indeterminate.
*/
/*
FUNCTION
<<strftime>>---flexible calendar time formatter
INDEX
strftime
ANSI_SYNOPSIS
#include <time.h>
size_t strftime(char *<[s]>, size_t <[maxsize]>,
const char *<[format]>, const struct tm *<[timp]>);
TRAD_SYNOPSIS
#include <time.h>
size_t strftime(<[s]>, <[maxsize]>, <[format]>, <[timp]>)
char *<[s]>;
size_t <[maxsize]>;
char *<[format]>;
struct tm *<[timp]>;
DESCRIPTION
<<strftime>> converts a <<struct tm>> representation of the time (at
<[timp]>) into a null-terminated string, starting at <[s]> and occupying
no more than <[maxsize]> characters.
You control the format of the output using the string at <[format]>.
<<*<[format]>>> can contain two kinds of specifications: text to be
copied literally into the formatted string, and time conversion
specifications. Time conversion specifications are two- and
three-character sequences beginning with `<<%>>' (use `<<%%>>' to
include a percent sign in the output). Each defined conversion
specification selects only the specified field(s) of calendar time
data from <<*<[timp]>>>, and converts it to a string in one of the
following ways:
o+
o %a
A three-letter abbreviation for the day of the week. [tm_wday]
o %A
The full name for the day of the week, one of `<<Sunday>>',
`<<Monday>>', `<<Tuesday>>', `<<Wednesday>>', `<<Thursday>>',
`<<Friday>>', or `<<Saturday>>'. [tm_wday]
o %b
A three-letter abbreviation for the month name. [tm_mon]
o %B
The full name of the month, one of `<<January>>', `<<February>>',
`<<March>>', `<<April>>', `<<May>>', `<<June>>', `<<July>>',
`<<August>>', `<<September>>', `<<October>>', `<<November>>',
`<<December>>'. [tm_mon]
o %c
A string representing the complete date and time, in the form
`<<"%a %b %e %H:%M:%S %Y">>' (example "Mon Apr 01 13:13:13
1992"). [tm_sec, tm_min, tm_hour, tm_mday, tm_mon, tm_year, tm_wday]
o %C
The century, that is, the year divided by 100 then truncated. For
4-digit years, the result is zero-padded and exactly two characters;
but for other years, there may a negative sign or more digits. In
this way, `<<%C%y>>' is equivalent to `<<%Y>>'. [tm_year]
o %d
The day of the month, formatted with two digits (from `<<01>>' to
`<<31>>'). [tm_mday]
o %D
A string representing the date, in the form `<<"%m/%d/%y">>'.
[tm_mday, tm_mon, tm_year]
o %e
The day of the month, formatted with leading space if single digit
(from `<<1>>' to `<<31>>'). [tm_mday]
o %E<<x>>
In some locales, the E modifier selects alternative representations of
certain modifiers <<x>>. But in the "C" locale supported by newlib,
it is ignored, and treated as %<<x>>.
o %F
A string representing the ISO 8601:2000 date format, in the form
`<<"%Y-%m-%d">>'. [tm_mday, tm_mon, tm_year]
o %g
The last two digits of the week-based year, see specifier %G (from
`<<00>>' to `<<99>>'). [tm_year, tm_wday, tm_yday]
o %G
The week-based year. In the ISO 8601:2000 calendar, week 1 of the year
includes January 4th, and begin on Mondays. Therefore, if January 1st,
2nd, or 3rd falls on a Sunday, that day and earlier belong to the last
week of the previous year; and if December 29th, 30th, or 31st falls
on Monday, that day and later belong to week 1 of the next year. For
consistency with %Y, it always has at least four characters.
Example: "%G" for Saturday 2nd January 1999 gives "1998", and for
Tuesday 30th December 1997 gives "1998". [tm_year, tm_wday, tm_yday]
o %h
A three-letter abbreviation for the month name (synonym for
"%b"). [tm_mon]
o %H
The hour (on a 24-hour clock), formatted with two digits (from
`<<00>>' to `<<23>>'). [tm_hour]
o %I
The hour (on a 12-hour clock), formatted with two digits (from
`<<01>>' to `<<12>>'). [tm_hour]
o %j
The count of days in the year, formatted with three digits
(from `<<001>>' to `<<366>>'). [tm_yday]
o %k
The hour (on a 24-hour clock), formatted with leading space if single
digit (from `<<0>>' to `<<23>>'). Non-POSIX extension. [tm_hour]
o %l
The hour (on a 12-hour clock), formatted with leading space if single
digit (from `<<1>>' to `<<12>>'). Non-POSIX extension. [tm_hour]
o %m
The month number, formatted with two digits (from `<<01>>' to `<<12>>').
[tm_mon]
o %M
The minute, formatted with two digits (from `<<00>>' to `<<59>>'). [tm_min]
o %n
A newline character (`<<\n>>').
o %O<<x>>
In some locales, the O modifier selects alternative digit characters
for certain modifiers <<x>>. But in the "C" locale supported by newlib, it
is ignored, and treated as %<<x>>.
o %p
Either `<<AM>>' or `<<PM>>' as appropriate. [tm_hour]
o %r
The 12-hour time, to the second. Equivalent to "%I:%M:%S %p". [tm_sec,
tm_min, tm_hour]
o %R
The 24-hour time, to the minute. Equivalent to "%H:%M". [tm_min, tm_hour]
o %S
The second, formatted with two digits (from `<<00>>' to `<<60>>'). The
value 60 accounts for the occasional leap second. [tm_sec]
o %t
A tab character (`<<\t>>').
o %T
The 24-hour time, to the second. Equivalent to "%H:%M:%S". [tm_sec,
tm_min, tm_hour]
o %u
The weekday as a number, 1-based from Monday (from `<<1>>' to
`<<7>>'). [tm_wday]
o %U
The week number, where weeks start on Sunday, week 1 contains the first
Sunday in a year, and earlier days are in week 0. Formatted with two
digits (from `<<00>>' to `<<53>>'). See also <<%W>>. [tm_wday, tm_yday]
o %V
The week number, where weeks start on Monday, week 1 contains January 4th,
and earlier days are in the previous year. Formatted with two digits
(from `<<01>>' to `<<53>>'). See also <<%G>>. [tm_year, tm_wday, tm_yday]
o %w
The weekday as a number, 0-based from Sunday (from `<<0>>' to `<<6>>').
[tm_wday]
o %W
The week number, where weeks start on Monday, week 1 contains the first
Monday in a year, and earlier days are in week 0. Formatted with two
digits (from `<<00>>' to `<<53>>'). [tm_wday, tm_yday]
o %x
A string representing the complete date, equivalent to "%m/%d/%y".
[tm_mon, tm_mday, tm_year]
o %X
A string representing the full time of day (hours, minutes, and
seconds), equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour]
o %y
The last two digits of the year (from `<<00>>' to `<<99>>'). [tm_year]
o %Y
The full year, equivalent to <<%C%y>>. It will always have at least four
characters, but may have more. The year is accurate even when tm_year
added to the offset of 1900 overflows an int. [tm_year]
o %z
The offset from UTC. The format consists of a sign (negative is west of
Greewich), two characters for hour, then two characters for minutes
(-hhmm or +hhmm). If tm_isdst is negative, the offset is unknown and no
output is generated; if it is zero, the offset is the standard offset for
the current time zone; and if it is positive, the offset is the daylight
savings offset for the current timezone. The offset is determined from
the TZ environment variable, as if by calling tzset(). [tm_isdst]
o %Z
The time zone name. If tm_isdst is negative, no output is generated.
Otherwise, the time zone name is based on the TZ environment variable,
as if by calling tzset(). [tm_isdst]
o %%
A single character, `<<%>>'.
o-
RETURNS
When the formatted time takes up no more than <[maxsize]> characters,
the result is the length of the formatted string. Otherwise, if the
formatting operation was abandoned due to lack of room, the result is
<<0>>, and the string starting at <[s]> corresponds to just those
parts of <<*<[format]>>> that could be completely filled in within the
<[maxsize]> limit.
PORTABILITY
ANSI C requires <<strftime>>, but does not specify the contents of
<<*<[s]>>> when the formatted string would require more than
<[maxsize]> characters. Unrecognized specifiers and fields of
<<timp>> that are out of range cause undefined results. Since some
formats expand to 0 bytes, it is wise to set <<*<[s]>>> to a nonzero
value beforehand to distinguish between failure and an empty string.
This implementation does not support <<s>> being NULL, nor overlapping
<<s>> and <<format>>.
<<strftime>> requires no supporting OS subroutines.
*/
#include <stddef.h>
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>
#include "local.h"
static _CONST int dname_len[7] =
{6, 6, 7, 9, 8, 6, 8};
static _CONST char *_CONST dname[7] =
{"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"};
static _CONST int mname_len[12] =
{7, 8, 5, 5, 3, 4, 4, 6, 9, 7, 8, 8};
static _CONST char *_CONST mname[12] =
{"January", "February", "March", "April",
"May", "June", "July", "August", "September", "October", "November",
"December"};
/* Using the tm_year, tm_wday, and tm_yday components of TIM_P, return
-1, 0, or 1 as the adjustment to add to the year for the ISO week
numbering used in "%g%G%V", avoiding overflow. */
static int
_DEFUN (iso_year_adjust, (tim_p),
_CONST struct tm *tim_p)
{
/* Account for fact that tm_year==0 is year 1900. */
int leap = isleap (tim_p->tm_year + (YEAR_BASE
- (tim_p->tm_year < 0 ? 0 : 2000)));
/* Pack the yday, wday, and leap year into a single int since there are so
many disparate cases. */
#define PACK(yd, wd, lp) (((yd) << 4) + (wd << 1) + (lp))
switch (PACK (tim_p->tm_yday, tim_p->tm_wday, leap))
{
case PACK (0, 5, 0): /* Jan 1 is Fri, not leap. */
case PACK (0, 6, 0): /* Jan 1 is Sat, not leap. */
case PACK (0, 0, 0): /* Jan 1 is Sun, not leap. */
case PACK (0, 5, 1): /* Jan 1 is Fri, leap year. */
case PACK (0, 6, 1): /* Jan 1 is Sat, leap year. */
case PACK (0, 0, 1): /* Jan 1 is Sun, leap year. */
case PACK (1, 6, 0): /* Jan 2 is Sat, not leap. */
case PACK (1, 0, 0): /* Jan 2 is Sun, not leap. */
case PACK (1, 6, 1): /* Jan 2 is Sat, leap year. */
case PACK (1, 0, 1): /* Jan 2 is Sun, leap year. */
case PACK (2, 0, 0): /* Jan 3 is Sun, not leap. */
case PACK (2, 0, 1): /* Jan 3 is Sun, leap year. */
return -1; /* Belongs to last week of previous year. */
case PACK (362, 1, 0): /* Dec 29 is Mon, not leap. */
case PACK (363, 1, 1): /* Dec 29 is Mon, leap year. */
case PACK (363, 1, 0): /* Dec 30 is Mon, not leap. */
case PACK (363, 2, 0): /* Dec 30 is Tue, not leap. */
case PACK (364, 1, 1): /* Dec 30 is Mon, leap year. */
case PACK (364, 2, 1): /* Dec 30 is Tue, leap year. */
case PACK (364, 1, 0): /* Dec 31 is Mon, not leap. */
case PACK (364, 2, 0): /* Dec 31 is Tue, not leap. */
case PACK (364, 3, 0): /* Dec 31 is Wed, not leap. */
case PACK (365, 1, 1): /* Dec 31 is Mon, leap year. */
case PACK (365, 2, 1): /* Dec 31 is Tue, leap year. */
case PACK (365, 3, 1): /* Dec 31 is Wed, leap year. */
return 1; /* Belongs to first week of next year. */
}
return 0; /* Belongs to specified year. */
#undef PACK
}
size_t
_DEFUN (strftime, (s, maxsize, format, tim_p),
char *s _AND
size_t maxsize _AND
_CONST char *format _AND
_CONST struct tm *tim_p)
{
size_t count = 0;
int i;
for (;;)
{
while (*format && *format != '%')
{
if (count < maxsize - 1)
s[count++] = *format++;
else
return 0;
}
if (*format == '\0')
break;
format++;
if (*format == 'E' || *format == 'O')
format++;
switch (*format)
{
case 'a':
for (i = 0; i < 3; i++)
{
if (count < maxsize - 1)
s[count++] =
dname[tim_p->tm_wday][i];
else
return 0;
}
break;
case 'A':
for (i = 0; i < dname_len[tim_p->tm_wday]; i++)
{
if (count < maxsize - 1)
s[count++] =
dname[tim_p->tm_wday][i];
else
return 0;
}
break;
case 'b':
case 'h':
for (i = 0; i < 3; i++)
{
if (count < maxsize - 1)
s[count++] =
mname[tim_p->tm_mon][i];
else
return 0;
}
break;
case 'B':
for (i = 0; i < mname_len[tim_p->tm_mon]; i++)
{
if (count < maxsize - 1)
s[count++] =
mname[tim_p->tm_mon][i];
else
return 0;
}
break;
case 'c':
{
/* Length is not known because of %C%y, so recurse. */
size_t adjust = strftime (&s[count], maxsize - count,
"%a %b %e %H:%M:%S %C%y", tim_p);
if (adjust > 0)
count += adjust;
else
return 0;
}
break;
case 'C':
{
/* Examples of (tm_year + YEAR_BASE) that show how %Y == %C%y
with 32-bit int.
%Y %C %y
2147485547 21474855 47
10000 100 00
9999 99 99
0999 09 99
0099 00 99
0001 00 01
0000 00 00
-001 -0 01
-099 -0 99
-999 -9 99
-1000 -10 00
-10000 -100 00
-2147481748 -21474817 48
Be careful of both overflow and sign adjustment due to the
asymmetric range of years.
*/
int neg = tim_p->tm_year < -YEAR_BASE;
int century = tim_p->tm_year >= 0
? tim_p->tm_year / 100 + YEAR_BASE / 100
: abs (tim_p->tm_year + YEAR_BASE) / 100;
count += snprintf (&s[count], maxsize - count, "%s%.*d",
neg ? "-" : "", 2 - neg, century);
if (count >= maxsize)
return 0;
}
break;
case 'd':
case 'e':
if (count < maxsize - 2)
{
sprintf (&s[count], *format == 'd' ? "%.2d" : "%2d",
tim_p->tm_mday);
count += 2;
}
else
return 0;
break;
case 'D':
case 'x':
/* %m/%d/%y */
if (count < maxsize - 8)
{
sprintf (&s[count], "%.2d/%.2d/%.2d",
tim_p->tm_mon + 1, tim_p->tm_mday,
tim_p->tm_year >= 0 ? tim_p->tm_year % 100
: abs (tim_p->tm_year + YEAR_BASE) % 100);
count += 8;
}
else
return 0;
break;
case 'F':
{
/* Length is not known because of %C%y, so recurse. */
size_t adjust = strftime (&s[count], maxsize - count,
"%C%y-%m-%d", tim_p);
if (adjust > 0)
count += adjust;
else
return 0;
}
break;
case 'g':
if (count < maxsize - 2)
{
/* Be careful of both overflow and negative years, thanks to
the asymmetric range of years. */
int adjust = iso_year_adjust (tim_p);
int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100
: abs (tim_p->tm_year + YEAR_BASE) % 100;
if (adjust < 0 && tim_p->tm_year <= -YEAR_BASE)
adjust = 1;
else if (adjust > 0 && tim_p->tm_year < -YEAR_BASE)
adjust = -1;
sprintf (&s[count], "%.2d",
((year + adjust) % 100 + 100) % 100);
count += 2;
}
else
return 0;
break;
case 'G':
{
/* See the comments for 'C' and 'Y'; this is a variable length
field. Although there is no requirement for a minimum number
of digits, we use 4 for consistency with 'Y'. */
int neg = tim_p->tm_year < -YEAR_BASE;
int adjust = iso_year_adjust (tim_p);
int century = tim_p->tm_year >= 0
? tim_p->tm_year / 100 + YEAR_BASE / 100
: abs (tim_p->tm_year + YEAR_BASE) / 100;
int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100
: abs (tim_p->tm_year + YEAR_BASE) % 100;
if (adjust < 0 && tim_p->tm_year <= -YEAR_BASE)
neg = adjust = 1;
else if (adjust > 0 && neg)
adjust = -1;
year += adjust;
if (year == -1)
{
year = 99;
--century;
}
else if (year == 100)
{
year = 0;
++century;
}
count += snprintf (&s[count], maxsize - count, "%s%.*d%.2d",
neg ? "-" : "", 2 - neg, century, year);
if (count >= maxsize)
return 0;
}
break;
case 'H':
case 'k':
if (count < maxsize - 2)
{
sprintf (&s[count], *format == 'k' ? "%2d" : "%.2d",
tim_p->tm_hour);
count += 2;
}
else
return 0;
break;
case 'I':
case 'l':
if (count < maxsize - 2)
{
if (tim_p->tm_hour == 0 ||
tim_p->tm_hour == 12)
{
s[count++] = '1';
s[count++] = '2';
}
else
{
sprintf (&s[count], *format == 'I' ? "%.2d" : "%2d",
tim_p->tm_hour % 12);
count += 2;
}
}
else
return 0;
break;
case 'j':
if (count < maxsize - 3)
{
sprintf (&s[count], "%.3d",
tim_p->tm_yday + 1);
count += 3;
}
else
return 0;
break;
case 'm':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
tim_p->tm_mon + 1);
count += 2;
}
else
return 0;
break;
case 'M':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
tim_p->tm_min);
count += 2;
}
else
return 0;
break;
case 'n':
if (count < maxsize - 1)
s[count++] = '\n';
else
return 0;
break;
case 'p':
if (count < maxsize - 2)
{
if (tim_p->tm_hour < 12)
s[count++] = 'A';
else
s[count++] = 'P';
s[count++] = 'M';
}
else
return 0;
break;
case 'r':
if (count < maxsize - 11)
{
if (tim_p->tm_hour == 0 ||
tim_p->tm_hour == 12)
{
s[count++] = '1';
s[count++] = '2';
}
else
{
sprintf (&s[count], "%.2d", tim_p->tm_hour % 12);
count += 2;
}
s[count++] = ':';
sprintf (&s[count], "%.2d",
tim_p->tm_min);
count += 2;
s[count++] = ':';
sprintf (&s[count], "%.2d",
tim_p->tm_sec);
count += 2;
s[count++] = ' ';
if (tim_p->tm_hour < 12)
s[count++] = 'A';
else
s[count++] = 'P';
s[count++] = 'M';
}
else
return 0;
break;
case 'R':
if (count < maxsize - 5)
{
sprintf (&s[count], "%.2d:%.2d", tim_p->tm_hour, tim_p->tm_min);
count += 5;
}
else
return 0;
break;
case 'S':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
tim_p->tm_sec);
count += 2;
}
else
return 0;
break;
case 't':
if (count < maxsize - 1)
s[count++] = '\t';
else
return 0;
break;
case 'T':
case 'X':
if (count < maxsize - 8)
{
sprintf (&s[count], "%.2d:%.2d:%.2d", tim_p->tm_hour,
tim_p->tm_min, tim_p->tm_sec);
count += 8;
}
else
return 0;
break;
case 'u':
if (count < maxsize - 1)
{
if (tim_p->tm_wday == 0)
s[count++] = '7';
else
s[count++] = '0' + tim_p->tm_wday;
}
else
return 0;
break;
case 'U':
if (count < maxsize - 2)
{
sprintf (&s[count], "%.2d",
(tim_p->tm_yday + 7 -
tim_p->tm_wday) / 7);
count += 2;
}
else
return 0;
break;
case 'V':
if (count < maxsize - 2)
{
int adjust = iso_year_adjust (tim_p);
int wday = (tim_p->tm_wday) ? tim_p->tm_wday - 1 : 6;
int week = (tim_p->tm_yday + 10 - wday) / 7;
if (adjust > 0)
week = 1;
else if (adjust < 0)
/* Previous year has 53 weeks if current year starts on
Fri, and also if current year starts on Sat and
previous year was leap year. */
week = 52 + (4 >= (wday - tim_p->tm_yday
- isleap (tim_p->tm_year
+ (YEAR_BASE - 1
- (tim_p->tm_year < 0
? 0 : 2000)))));
sprintf (&s[count], "%.2d", week);
count += 2;
}
else
return 0;
break;
case 'w':
if (count < maxsize - 1)
s[count++] = '0' + tim_p->tm_wday;
else
return 0;
break;
case 'W':
if (count < maxsize - 2)
{
int wday = (tim_p->tm_wday) ? tim_p->tm_wday - 1 : 6;
sprintf (&s[count], "%.2d",
(tim_p->tm_yday + 7 - wday) / 7);
count += 2;
}
else
return 0;
break;
case 'y':
if (count < maxsize - 2)
{
/* Be careful of both overflow and negative years, thanks to
the asymmetric range of years. */
int year = tim_p->tm_year >= 0 ? tim_p->tm_year % 100
: abs (tim_p->tm_year + YEAR_BASE) % 100;
sprintf (&s[count], "%.2d", year);
count += 2;
}
else
return 0;
break;
case 'Y':
{
/* Length is not known because of %C%y, so recurse. */
size_t adjust = strftime (&s[count], maxsize - count,
"%C%y", tim_p);
if (adjust > 0)
count += adjust;
else
return 0;
}
break;
case 'z':
if (tim_p->tm_isdst >= 0)
{
if (count < maxsize - 5)
{
long offset;
__tzinfo_type *tz = __gettzinfo ();
TZ_LOCK;
/* The sign of this is exactly opposite the envvar TZ. We
could directly use the global _timezone for tm_isdst==0,
but have to use __tzrule for daylight savings. */
offset = -tz->__tzrule[tim_p->tm_isdst > 0].offset;
TZ_UNLOCK;
sprintf (&s[count], "%+03ld%.2ld", offset / SECSPERHOUR,
labs (offset / SECSPERMIN) % 60L);
count += 5;
}
else
return 0;
}
break;
case 'Z':
if (tim_p->tm_isdst >= 0)
{
int size;
TZ_LOCK;
size = strlen(_tzname[tim_p->tm_isdst > 0]);
for (i = 0; i < size; i++)
{
if (count < maxsize - 1)
s[count++] = _tzname[tim_p->tm_isdst > 0][i];
else
{
TZ_UNLOCK;
return 0;
}
}
TZ_UNLOCK;
}
break;
case '%':
if (count < maxsize - 1)
s[count++] = '%';
else
return 0;
break;
}
if (*format)
format++;
else
break;
}
if (maxsize)
s[count] = '\0';
return count;
}
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