From 56d4e7fb86f3ecdda93e9a4f79f84f1655c85174 Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Thu, 29 Aug 2019 23:17:30 +0000
Subject: [PATCH] Date/Time: Restore the previous behavior of `date_i18n()`
 where invalid input would result in current time.

Make `wp_date()` return `false` on invalid timestamp input, for consistency with upstream PHP `date()` function.

Props Rarst.
Fixes #28636.

git-svn-id: https://develop.svn.wordpress.org/trunk@45914 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/functions.php            | 12 +++++++++---
 tests/phpunit/tests/date/currentTime.php |  2 +-
 tests/phpunit/tests/date/dateI18n.php    | 15 +++++++++++++++
 tests/phpunit/tests/date/theDate.php     |  2 +-
 tests/phpunit/tests/date/wpDate.php      | 15 +++++++++++++++
 tests/phpunit/tests/date/wpTimezone.php  |  2 +-
 6 files changed, 42 insertions(+), 6 deletions(-)
 create mode 100644 tests/phpunit/tests/date/wpDate.php

diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 8a7897a909..3acfe7318e 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -163,8 +163,12 @@ function wp_timezone() {
  * @return string The date, translated if locale specifies it.
  */
 function date_i18n( $format, $timestamp_with_offset = false, $gmt = false ) {
+	$timestamp = $timestamp_with_offset;
+
 	// If timestamp is omitted it should be current time (summed with offset, unless `$gmt` is true).
-	$timestamp = $timestamp_with_offset ? $timestamp_with_offset : current_time( 'timestamp', $gmt );
+	if ( ! is_numeric( $timestamp ) ) {
+		$timestamp = current_time( 'timestamp', $gmt );
+	}
 
 	/*
 	 * This is a legacy implementation quirk that the returned timestamp is also with offset.
@@ -218,13 +222,15 @@ function date_i18n( $format, $timestamp_with_offset = false, $gmt = false ) {
  * @param int          $timestamp Optional. Unix timestamp. Defaults to current time.
  * @param DateTimeZone $timezone  Optional. Timezone to output result in. Defaults to timezone
  *                                from site settings.
- * @return string The date, translated if locale specifies it.
+ * @return string|false The date, translated if locale specifies it. False on invalid timestamp input.
  */
 function wp_date( $format, $timestamp = null, $timezone = null ) {
 	global $wp_locale;
 
-	if ( ! $timestamp ) {
+	if ( null === $timestamp ) {
 		$timestamp = time();
+	} elseif ( ! is_numeric( $timestamp ) ) {
+		return false;
 	}
 
 	if ( ! $timezone ) {
diff --git a/tests/phpunit/tests/date/currentTime.php b/tests/phpunit/tests/date/currentTime.php
index 8a38574d98..836f2737ee 100644
--- a/tests/phpunit/tests/date/currentTime.php
+++ b/tests/phpunit/tests/date/currentTime.php
@@ -4,7 +4,7 @@
  * @group date
  * @group datetime
  */
-class Tests_Date_CurrentTime extends WP_UnitTestCase {
+class Tests_Date_Current_Time extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 37440
diff --git a/tests/phpunit/tests/date/dateI18n.php b/tests/phpunit/tests/date/dateI18n.php
index 8f98c93ee6..5a13e3c437 100644
--- a/tests/phpunit/tests/date/dateI18n.php
+++ b/tests/phpunit/tests/date/dateI18n.php
@@ -5,6 +5,20 @@
  * @group datetime
  */
 class Tests_Date_I18n extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 28636
+	 */
+	public function test_should_return_current_time_on_invalid_timestamp() {
+		$timezone = 'Europe/Kiev';
+		update_option( 'timezone_string', $timezone );
+
+		$datetime     = new DateTime( 'now', new DateTimeZone( $timezone ) );
+		$wp_timestamp = $datetime->getTimestamp() + $datetime->getOffset();
+
+		$this->assertEquals( $wp_timestamp, date_i18n( 'U', 'invalid' ), '', 5 );
+	}
+
 	public function test_should_format_date() {
 		$this->assertEquals( strtotime( gmdate( 'Y-m-d H:i:s' ) ), strtotime( date_i18n( 'Y-m-d H:i:s' ) ), 'The dates should be equal', 2 );
 	}
@@ -74,6 +88,7 @@ class Tests_Date_I18n extends WP_UnitTestCase {
 		update_option( 'timezone_string', '' );
 		$offset = $datetimezone->getOffset( new DateTime() ) / 3600;
 		update_option( 'gmt_offset', $offset );
+
 		$datetime = new DateTime( 'now', $datetimezone );
 		$datetime = new DateTime( $datetime->format( 'P' ) );
 
diff --git a/tests/phpunit/tests/date/theDate.php b/tests/phpunit/tests/date/theDate.php
index 1f6c1d1a42..2542240d6b 100644
--- a/tests/phpunit/tests/date/theDate.php
+++ b/tests/phpunit/tests/date/theDate.php
@@ -4,7 +4,7 @@
  * @group date
  * @group datetime
  */
-class Tests_Date_TheDate extends WP_UnitTestCase {
+class Tests_Date_The_Date extends WP_UnitTestCase {
 
 	/** @var array $hooks_called Count of hooks called. */
 	protected $hooks_called = array(
diff --git a/tests/phpunit/tests/date/wpDate.php b/tests/phpunit/tests/date/wpDate.php
new file mode 100644
index 0000000000..d3fb58aba2
--- /dev/null
+++ b/tests/phpunit/tests/date/wpDate.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @group date
+ * @group datetime
+ */
+class Tests_Date_WP_Date extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 28636
+	 */
+	public function test_should_return_false_on_invalid_timestamp() {
+		$this->assertFalse( wp_date( DATE_RFC3339, 'invalid' ) );
+	}
+}
diff --git a/tests/phpunit/tests/date/wpTimezone.php b/tests/phpunit/tests/date/wpTimezone.php
index b4ab35ea9b..359ab1244f 100644
--- a/tests/phpunit/tests/date/wpTimezone.php
+++ b/tests/phpunit/tests/date/wpTimezone.php
@@ -4,7 +4,7 @@
  * @group date
  * @group datetime
  */
-class Tests_WP_Timezone extends WP_UnitTestCase {
+class Tests_Date_WP_Timezone extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 24730