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Bug #79104 Relative DateInterval Creates Infinite Loop
Submitted: 2020-01-11 21:42 UTC Modified: 2020-01-23 21:41 UTC
Votes:1
Avg. Score:5.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:0 (0.0%)
Same OS:0 (0.0%)
From: jimbo2150 at gmail dot com Assigned: derick (profile)
Status: Assigned Package: Date/time related
PHP Version: 7.3.13 OS:
Private report: No CVE-ID: None
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 [2020-01-11 21:42 UTC] jimbo2150 at gmail dot com
Description:
------------
A relative date format used in DateInterval produces and infinite loop when used with DatePeriod.

An example is looking for the first Monday in January of each year. When iterated via DatePeriod the year will not get iterated and the correct relative date for current year keeps getting returned creating an infinite loop.

Test script:
---------------
// Looking for every Monday of January each year
$fmj = DateInterval::createFromDateString('first Monday of January');

$period = new DatePeriod(new DateTime('2020-01-01'), $fmj, new DateTime('2022-01-11'));

// Infinite loop, first Monday of January of current year keeps getting iterated
foreach ($period as $dt) {
    var_dump($dt->format("l Y-m-d H:i:s"));
}

Expected result:
----------------
Return each first Monday of January for the next 2 years.

string(30) "Wednesday 2020-01-01 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2021-01-04 00:00:00"
string(27) "Monday 2022-01-03 00:00:00"

Actual result:
--------------
Infinite loop where each date is the first Monday of the current year's January.

string(30) "Wednesday 2020-01-01 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
string(27) "Monday 2020-01-06 00:00:00"
...
{infinite loop}

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 [2020-01-19 11:04 UTC] a at b dot c dot de
Looks like it can't determine how long "first Monday of January" is.

echo $fmj->format('%y years, %m months, %d days, %h hours, %i minutes, %s seconds');

What numbers should it be using for those fields?
 [2020-01-20 16:53 UTC] girgias@php.net
-Assigned To: +Assigned To: derick
 [2020-01-23 21:41 UTC] jimbo2150 at gmail dot com
Not sure what you mean by the numbers you are looking for.

I got closer with this code (added "next year" to the DatePeriod object, but the result is erratic (not sure what is being calculated):


$fmj = DateInterval::createFromDateString('first Monday of January next year');

$period = new DatePeriod(new DateTime('first Monday of January 2020'), $fmj, new DateTime('2022-01-31'));

foreach ($period as $dt) {
    var_dump($dt->format("l Y-m-d H:i:s"));
}

// Strange, incorrect output (not the first Monday of January 2021 or 2022):
string(26) "Monday 2020-01-06 00:00:00"
string(29) "Wednesday 2021-01-06 00:00:00"
string(27) "Tuesday 2022-01-04 00:00:00"
 [2020-01-23 23:52 UTC] antonino dot spampinato86 at gmail dot com
$timezone = new DateTimeZone( "UTC" );
$fmj = DateInterval::createFromDateString( 'first Monday of January 2020' );
//Monday from start 2019 only
$period = new DatePeriod( new DateTime( '2019-01-01 00:00:00.000000', $timezone ), $fmj, new DateTime( '2022-01-11 00:00:00.000000', $timezone ) );

$y = 0;
foreach ( $period as $dt ) {

    $display[$y++] = $dt->format( "l Y-m-d H:i:s" );
		//stop total_recurrence
		if( $y == 5 ) {
			break;
		}
}
Manually stop infinite loop :)
The relative date, first Monday of jenaury is extended for the current year but for the parametres start and end of function DatePeriod , only uses the start, there are two bugs in the php source code, the reference is not counted if the code does not return the expected result, the second bug is stopping on start.
 [2020-01-24 12:15 UTC] antonino dot spampinato86 at gmail dot com
observe the behavior of DateTime, this code expands the relative date for the current year while for DatePeriod it must not expand for the current year but must use the value for the start and end year, it means if I have a year explicitly expressed DatePeriod result must be for the year expressed otherwise if the year is not expressed it recovers the start and end of DatePeriod.
$var = new DateTime( 'first monday of January', new DateTimeZone( "UTC" );
$display[5] = $var->format( "l Y-m-d H:i:s" );
var_dump( $display );
 
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