Edit report at http://bugs.php.net/bug.php?id=52744&edit=1
ID: 52744
Updated by: aharvey@php.net
Reported by: gpap at internet dot gr
-Summary: cal_days_in_month
+Summary: cal_days_in_month incorrect for December 1 BCE
-Status: Assigned
+Status: Closed
Type: Bug
Package: Calendar related
Operating System: all
PHP Version: 5.3SVN-2010-08-30 (snap)
Assigned To: aharvey
Block user comment: N
New Comment:
This bug has been fixed in SVN.
Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
Thank you for the report, and for helping us make PHP better.
Thank you very much for the patch!
Previous Comments:
------------------------------------------------------------------------
[2010-09-09 08:41:25] aharvey@php.net
Automatic comment from SVN on behalf of aharvey
Revision: http://svn.php.net/viewvc/?view=revision&revision=303203
Log: Fixed bug #52744 (cal_days_in_month incorrect for December 1 BCE).
Original
patch by gpap at internet dot gr.
------------------------------------------------------------------------
[2010-08-30 18:16:53] gpap at internet dot gr
Description:
------------
Function cal_days_in_month returns wrong result for December 1 BCE:
echo cal_days_in_month(CAL_GREGORIAN, 12, -1) returns -1721395
echo cal_days_in_month(CAL_JULIAN, 12, -1) returns -1721393
The function uses julian day count internally to calculate the day count
difference between the 1st day of the supplied month and the 1st day of
the next
month. The next month of December 1 BCE (year -1) is January 1 CE (year
1, there
is no year zero).
But when cal_days_in_month calculates the next year as year+1, it does
not check
for year zero, so it tries to calculate the julian day for 1st January
0, which
returns 0 and consequently the wrong result of days in December 1 BCE is
returned.
actual function code taken from latest svn snapshot php5.3-201008301230
(/ext/calendar.c):
-----------------------
PHP_FUNCTION(cal_days_in_month)
{
long cal, month, year;
struct cal_entry_t *calendar;
long sdn_start, sdn_next;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "lll",
&cal,
&month, &year) == FAILURE) {
RETURN_FALSE;
}
if (cal < 0 || cal >= CAL_NUM_CALS) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "invalid
calendar ID
%ld.", cal);
RETURN_FALSE;
}
calendar = &cal_conversion_table[cal];
sdn_start = calendar->to_jd(year, month, 1);
if (sdn_start == 0) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "invalid
date.");
RETURN_FALSE;
}
sdn_next = calendar->to_jd(year, 1 + month, 1);
if (sdn_next == 0) {
/* if invalid, try first month of the next year... */
sdn_next = calendar->to_jd(year + 1, 1, 1);
}
RETURN_LONG(sdn_next - sdn_start);
}
-----------------------
The following correction is proposed:
-----------------------
if (sdn_next == 0) {
/* if invalid, try first month of the next year... */
- sdn_next = calendar->to_jd(year + 1, 1, 1);
+ if (year == -1) {
+ sdn_next = calendar->to_jd(1, 1, 1);
+ } else {
+ sdn_next = calendar->to_jd(year + 1, 1, 1);
+ }
}
-----------------------
Test script:
---------------
<?php
// returns -1721395 instead of 31
echo cal_days_in_month(CAL_GREGORIAN, 12, -1);
// returns -1721393 instead of 31
echo cal_days_in_month(CAL_JULIAN, 12, -1);
?>
Expected result:
----------------
31
31
Actual result:
--------------
-1721395
-1721393
------------------------------------------------------------------------
--
Edit this bug report at http://bugs.php.net/bug.php?id=52744&edit=1