From 6f15251aa487aef1aa825d48e870cd7db0f311fc Mon Sep 17 00:00:00 2001
From: Sergey Biryukov <sergeybiryukov@git.wordpress.org>
Date: Tue, 4 Feb 2020 22:13:15 +0000
Subject: [PATCH] Posts, Post Types: Fail gracefully when checking mapped cap
 against unregistered post status.

With `map_meta_cap` enabled for a post type, the `read_post` capability for posts with a public status is supposed to be mapped to the post type's `read` capability.

When a post is left in the database after the post status is no longer present, and WP does a `read_post` check against it, a PHP notice was thrown, and the cap check always failed.

As a more graceful fallback, the cap is now mapped onto `edit_others_posts`, which allows highly privileged users to be able to access orphaned content.

A `_doing_it_wrong()` notice is also added, so that developers and site administrators are aware that the cap mapping is failing in the absence of the registered post status.

Follow-up to [34091], which introduced a similar approach to checking mapped caps against an unregistered post type.

Props roytanck, SergeyBiryukov.
Fixes #48653.

git-svn-id: https://develop.svn.wordpress.org/trunk@47178 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/capabilities.php          |  7 +++++++
 tests/phpunit/tests/user/capabilities.php | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/src/wp-includes/capabilities.php b/src/wp-includes/capabilities.php
index 38287dc7c3..f05c504cc1 100644
--- a/src/wp-includes/capabilities.php
+++ b/src/wp-includes/capabilities.php
@@ -241,6 +241,13 @@ function map_meta_cap( $cap, $user_id, ...$args ) {
 			}
 
 			$status_obj = get_post_status_object( $post->post_status );
+			if ( ! $status_obj ) {
+				/* translators: 1: Post status, 2: Capability name. */
+				_doing_it_wrong( __FUNCTION__, sprintf( __( 'The post status %1$s is not registered, so it may not be reliable to check the capability "%2$s" against a post with that status.' ), $post->post_status, $cap ), '5.4.0' );
+				$caps[] = 'edit_others_posts';
+				break;
+			}
+
 			if ( $status_obj->public ) {
 				$caps[] = $post_type->cap->read;
 				break;
diff --git a/tests/phpunit/tests/user/capabilities.php b/tests/phpunit/tests/user/capabilities.php
index 4e4ea12035..a5b7f3c55d 100644
--- a/tests/phpunit/tests/user/capabilities.php
+++ b/tests/phpunit/tests/user/capabilities.php
@@ -1773,6 +1773,29 @@ class Tests_User_Capabilities extends WP_UnitTestCase {
 		}
 	}
 
+	/**
+	 * @ticket 48653
+	 * @expectedIncorrectUsage map_meta_cap
+	 */
+	function test_require_edit_others_posts_if_post_status_doesnt_exist() {
+		register_post_status( 'existed' );
+		$post_id = self::factory()->post->create( array( 'post_status' => 'existed' ) );
+		_unregister_post_status( 'existed' );
+
+		$subscriber_id = self::$users['subscriber']->ID;
+		$editor_id     = self::$users['editor']->ID;
+
+		foreach ( array( 'read_post', 'read_page' ) as $cap ) {
+			wp_set_current_user( $subscriber_id );
+			$this->assertSame( array( 'edit_others_posts' ), map_meta_cap( $cap, $subscriber_id, $post_id ) );
+			$this->assertFalse( current_user_can( $cap, $post_id ) );
+
+			wp_set_current_user( $editor_id );
+			$this->assertSame( array( 'edit_others_posts' ), map_meta_cap( $cap, $editor_id, $post_id ) );
+			$this->assertTrue( current_user_can( $cap, $post_id ) );
+		}
+	}
+
 	/**
 	 * @ticket 17253
 	 */