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strftime improvements
- From: Eric Blake <ebb9 at byu dot net>
- To: newlib at sources dot redhat dot com
- Date: Mon, 14 Feb 2005 07:08:08 -0700
- Subject: strftime improvements
Following up to my post last month about broken strftime(3), here is a
patch that implements all the remaining missing functionality required by
POSIX, as well as improving the documentation.
Note that there are still some useful non-POSIX extensions out there that
might be worth implementing. In glibc, strftime(NULL, (size_t)UINT_MAX,
format, &tm) returns the number of characters that would be placed into a
non-NULL string, great for allocating a string to have exact length. And
in Solaris, strftime(s, len, NULL, &tm) uses "%c" as the default format.
Also, something I did not know how to fix - POSIX requires that <time.h>
include extern int daylight, extern long timezone, and extern char
*tzname. But as currently written, <time.h> has daylight and tzname
exposed only under __CYGWIN__, and timezone is a function instead of a
long unless timezonevar is defined.
2005-02-14 Eric Blake <ebb9@byu.net>
* libc/time/time.tex: Improve the documentation.
* libc/time/strftime.c: Improve the documentation.
(iso_year_adjust): New helper function.
(strftime): Simplify '%E' and '%O'. Change '%c' to use
recursion. Fix '%C', '%y', and '%Y' to deal with years with more
than 4 characters. Combine '%d' and '%e'. Implement '%D', '%F',
'%g', '%G', '%n', '%R', '%t', '%T', '%u', '%V', '%X', and '%z'.
Avoid core dumps on valid inputs (maxsize == 0, or
tim_p->tm_isdst > 1).
--
Life is short - so eat dessert first!
Eric Blake ebb9@byu.net
Index: strftime.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/time/strftime.c,v
retrieving revision 1.6
diff -u -p -r1.6 strftime.c
--- strftime.c 20 Jan 2005 19:56:27 -0000 1.6
+++ strftime.c 14 Feb 2005 13:46:50 -0000
@@ -32,96 +32,195 @@ TRAD_SYNOPSIS
DESCRIPTION
<<strftime>> converts a <<struct tm>> representation of the time (at
-<[timp]>) into a string, starting at <[s]> and occupying no more than
-<[maxsize]> characters.
+<[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-character
-sequences beginning with `<<%>>' (use `<<%%>>' to include a percent
-sign in the output). Each defined conversion specification selects a
-field of calendar time data from <<*<[timp]>>>, and converts it to a
-string in one of the following ways:
+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
-An abbreviation for the day of the week.
+A three-letter abbreviation for the day of the week. [tm_wday]
o %A
-The full name for the day of the week.
+The full name for the day of the week, one of `<<Sunday>>',
+`<<Monday>>', `<<Tuesday>>', `<<Wednesday>>', `<<Thursday>>',
+`<<Friday>>', or `<<Saturday>>'. [tm_wday]
o %b
-An abbreviation for the month name.
+A three-letter abbreviation for the month name. [tm_mon]
o %B
-The full name of the month.
+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
-. Mon Apr 01 13:13:13 1992
+`<<"%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.
+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.
+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 week 53
+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.
+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.
+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>>').
+(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.
+The month number, formatted with two digits (from `<<01>>' to `<<12>>').
+[tm_mon]
o %M
-The minute, formatted with two digits.
+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.
+Either `<<AM>>' or `<<PM>>' as appropriate. [tm_hour]
o %r
-Equivalent to "%I:%M:%S %p".
+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.
+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, formatted with two digits (from `<<00>>' to `<<53>>';
-week number 1 is taken as beginning with the first Sunday in a year).
-See also <<%W>>.
+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
-A single digit representing the day of the week: Sunday is day <<0>>.
+The weekday as a number, 0-based from Sunday (from `<<0>>' to `<<6>>').
+[tm_wday]
o %W
-Another version of the week number: like `<<%U>>', but counting week 1
-as beginning with the first Monday in a year.
+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
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 "%T".
+seconds), equivalent to "%H:%M:%S". [tm_sec, tm_min, tm_hour]
o %y
-The last two digits of the year.
+The last two digits of the year (from `<<00>>' to `<<99>>'). [tm_year]
o %Y
-The full year, formatted with four digits to include the century.
+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 -1, no output is generated.
-Otherwise, the time zone name based on the TZ environment variable
-is used.
+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, `<<%>>'.
@@ -138,7 +237,12 @@ parts of <<*<[format]>>> that could be c
PORTABILITY
ANSI C requires <<strftime>>, but does not specify the contents of
<<*<[s]>>> when the formatted string would require more than
-<[maxsize]> characters.
+<[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.
*/
@@ -164,6 +268,53 @@ static _CONST char *_CONST mname[12] =
"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
@@ -188,8 +339,8 @@ _DEFUN (strftime, (s, maxsize, format, t
break;
format++;
-
-check_format:
+ if (*format == 'E' || *format == 'O')
+ format++;
switch (*format)
{
@@ -235,68 +386,140 @@ check_format:
}
break;
case 'c':
- if (count < maxsize - 24)
- {
- for (i = 0; i < 3; i++)
- s[count++] =
- dname[tim_p->tm_wday][i];
- s[count++] = ' ';
- for (i = 0; i < 3; i++)
- s[count++] =
- mname[tim_p->tm_mon][i];
-
- sprintf (&s[count],
- " %.2d %2.2d:%2.2d:%2.2d %.4d",
- tim_p->tm_mday, tim_p->tm_hour,
- tim_p->tm_min,
- tim_p->tm_sec, 1900 +
- tim_p->tm_year);
- count += 17;
- }
- else
- return 0;
+ {
+ /* 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], "%.2d",
+ sprintf (&s[count], *format == 'd' ? "%.2d" : "%2d",
tim_p->tm_mday);
count += 2;
}
else
return 0;
break;
- case 'E':
- ++format;
- switch (*format)
- {
- case 'c':
- case 'C':
- case 'x':
- case 'X':
- case 'y':
- case 'Y':
- /* Ignore. */
- goto check_format;
- default:
- --format;
- }
+ 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 % 100 + 100) % 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 'e':
+ case 'g':
if (count < maxsize - 2)
{
- sprintf (&s[count], "%2d",
- tim_p->tm_mday);
+ /* 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;
+ 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" : "%2.2d",
+ sprintf (&s[count], *format == 'k' ? "%2d" : "%.2d",
tim_p->tm_hour);
count += 2;
}
@@ -315,7 +538,7 @@ check_format:
}
else
{
- sprintf (&s[count], (*format == 'I') ? "%.2d" : "%2d",
+ sprintf (&s[count], *format == 'I' ? "%.2d" : "%2d",
tim_p->tm_hour % 12);
count += 2;
}
@@ -346,36 +569,19 @@ check_format:
case 'M':
if (count < maxsize - 2)
{
- sprintf (&s[count], "%2.2d",
+ sprintf (&s[count], "%.2d",
tim_p->tm_min);
count += 2;
}
else
return 0;
break;
- case 'O':
- ++format;
- switch (*format)
- {
- case 'd':
- case 'e':
- case 'H':
- case 'I':
- case 'm':
- case 'M':
- case 'S':
- case 'u':
- case 'U':
- case 'V':
- case 'w':
- case 'W':
- case 'y':
- /* Ignore. */
- goto check_format;
- default:
- --format;
- }
- break;
+ case 'n':
+ if (count < maxsize - 1)
+ s[count++] = '\n';
+ else
+ return 0;
+ break;
case 'p':
if (count < maxsize - 2)
{
@@ -404,11 +610,11 @@ check_format:
count += 2;
}
s[count++] = ':';
- sprintf (&s[count], "%2.2d",
+ sprintf (&s[count], "%.2d",
tim_p->tm_min);
count += 2;
s[count++] = ':';
- sprintf (&s[count], "%2.2d",
+ sprintf (&s[count], "%.2d",
tim_p->tm_sec);
count += 2;
s[count++] = ' ';
@@ -422,20 +628,57 @@ check_format:
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], "%2.2d",
+ 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], "%2.2d",
+ sprintf (&s[count], "%.2d",
(tim_p->tm_yday + 7 -
tim_p->tm_wday) / 7);
count += 2;
@@ -443,57 +686,42 @@ check_format:
else
return 0;
break;
- case 'w':
- if (count < maxsize - 1)
- {
- sprintf (&s[count], "%1.1d",
- tim_p->tm_wday);
- count++;
- }
- else
- return 0;
- break;
- case 'W':
+ 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;
- sprintf (&s[count], "%2.2d",
- (tim_p->tm_yday + 7 -
- wday) / 7);
+ 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 'x':
- if (count < maxsize - 8)
- {
- sprintf (&s[count], "%.2d",
- tim_p->tm_mon + 1);
- count += 2;
- s[count++] = '/';
- sprintf (&s[count], "%.2d",
- tim_p->tm_mday);
- count += 2;
- s[count++] = '/';
- /* The year could be greater than 100, so we need the value
- modulo 100. The year could be negative, so we need to
- correct for a possible negative remainder. */
- sprintf (&s[count], "%2.2d",
- (tim_p->tm_year % 100 + 100) % 100);
- count += 2;
- }
+ break;
+ case 'w':
+ if (count < maxsize - 1)
+ s[count++] = '0' + tim_p->tm_wday;
else
return 0;
break;
- case 'X':
- if (count < maxsize - 8)
+ case 'W':
+ if (count < maxsize - 2)
{
- sprintf (&s[count],
- "%2.2d:%2.2d:%2.2d",
- tim_p->tm_hour, tim_p->tm_min,
- tim_p->tm_sec);
- count += 8;
+ 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;
@@ -501,36 +729,57 @@ check_format:
case 'y':
if (count < maxsize - 2)
{
- /* The year could be greater than 100, so we need the value
- modulo 100. The year could be negative, so we need to
- correct for a possible negative remainder. */
- sprintf (&s[count], "%2.2d",
- (tim_p->tm_year % 100 + 100) % 100);
+ /* 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':
- if (count < maxsize - 4)
- {
- sprintf (&s[count], "%.4d",
- 1900 + tim_p->tm_year);
- count += 4;
- }
- else
- return 0;
+ {
+ /* 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)
+ {
+ int offset;
+ 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 = -__tzrule[tim_p->tm_isdst > 0].offset;
+ TZ_UNLOCK;
+ sprintf (&s[count], "%+03d%.2d", offset / SECSPERHOUR,
+ abs (offset / SECSPERMIN) % 60);
+ 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]);
+ 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][i];
+ s[count++] = _tzname[tim_p->tm_isdst > 0][i];
else
{
TZ_UNLOCK;
@@ -552,7 +801,8 @@ check_format:
else
break;
}
- s[count] = '\0';
+ if (maxsize)
+ s[count] = '\0';
return count;
}
Index: time.tex
===================================================================
RCS file: /cvs/src/src/newlib/libc/time/time.tex,v
retrieving revision 1.3
diff -u -p -r1.3 time.tex
--- time.tex 16 Sep 2004 21:14:45 -0000 1.3
+++ time.tex 14 Feb 2005 13:46:50 -0000
@@ -18,28 +18,28 @@ the following fields:
@table @code
@item tm_sec
-Seconds.
+Seconds, between 0 and 60 inclusive (60 allows for leap seconds).
@item tm_min
-Minutes.
+Minutes, between 0 and 59 inclusive.
@item tm_hour
-Hours.
+Hours, between 0 and 23 inclusive.
@item tm_mday
-Day.
+Day of the month, between 1 and 31 inclusive.
@item tm_mon
-Month.
+Month, between 0 (January) and 11 (December).
@item tm_year
-Year (since 1900).
+Year (since 1900), can be negative for earlier years.
@item tm_wday
-Day of week: the number of days since Sunday.
+Day of week, between 0 (Sunday) and 6 (Saturday).
@item tm_yday
-Number of days elapsed since last January 1.
+Number of days elapsed since last January 1, between 0 and 365 inclusive.
@item tm_isdst
Daylight Savings Time flag: positive means DST in effect, zero means DST