Canonical: Add the ability to disable redirect_guess_404_permalink().

This also adds a few more filters to make adding redirects easier. Notably:

1. `do_redirect_guess_404_permalink`
2. `pre_redirect_guess_404_permalink`
3. `strict_redirect_guess_404_permalink`

Fixes: #16557.
Props: msafi, nacin, simonwheatley, westi, mboynes, joostdevalk, Lex_Robinson, MikeSchinkel, haukep, paulschreiber, DrewAPicture, ravenswd, esemlabel, stevegibson12, martychc23, DrLightman, jivanpal, neonkowy, laternastudio, apedog, audrasjb, davidbaumwald, Confridin, donmhico, ryotsun. 



git-svn-id: https://develop.svn.wordpress.org/trunk@47878 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/canonical.php

@@ -835,8 +835,52 @@ function strip_fragment_from_url( $url ) {
 function redirect_guess_404_permalink() {
 	global $wpdb;
 
+	/**
+	 * Filters whether to do redirect guess of 404 requests.
+	 *
+	 * Returning a false value from the filter will disable redirect guess 404 permalink.
+	 * and return early.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param bool     $do_redirect_guess  Whether to do redirect guess 404 permalink. Default true.
+	 */
+	if ( false === apply_filters( 'do_redirect_guess_404_permalink', true ) ) {
+		return false;
+	}
+
+	/**
+	 * Filters whether to short-circuit redirect guess of 404 requests.
+	 *
+	 * Return a non-false value from the filter will short-circuit the handling and return early.
+	 *
+	 * @since 5.5.0
+	 *
+	 * @param bool     $pre  Whether to short-circuit redirect guess 404 permalink. Default null.
+	 */
+	$pre = apply_filters( 'pre_redirect_guess_404_permalink', null );
+	if ( null !== $pre ) {
+		return $pre;
+	}
+
 	if ( get_query_var( 'name' ) ) {
+
+		/**
+		 * Filters whether to do a strict or loose guess.
+		 *
+		 * Returning true value from the filter will guess redirect only exact post_name matches.
+		 *
+		 * @since 5.5.0
+		 *
+		 * @param bool     $strict_guess  Whether to do a strict/exact guess. Default false.
+		 */
+		$strict_guess = apply_filters( 'strict_redirect_guess_404_permalink', false );
+
+		if ( $strict_guess ) {
+			$where = $wpdb->prepare( 'post_name = %s', get_query_var( 'name' ) );
+		} else {
 			$where = $wpdb->prepare( 'post_name LIKE %s', $wpdb->esc_like( get_query_var( 'name' ) ) . '%' );
+		}
 
 		// If any of post_type, year, monthnum, or day are set, use them to refine the query.
 		if ( get_query_var( 'post_type' ) ) {

tests/phpunit/tests/canonical.php

@@ -230,6 +230,51 @@ class Tests_Canonical extends WP_Canonical_UnitTestCase {
 		);
 	}
 
+	/**
+	 * @ticket 16557
+	 */
+	public function test_do_redirect_guess_404_permalink() {
+		// Test disable do_redirect_guess_404_permalink().
+		add_filter( 'do_redirect_guess_404_permalink', '__return_false' );
+		$this->go_to( '/child-page-1' );
+		$this->assertFalse( redirect_guess_404_permalink() );
+	}
+
+	/**
+	 * @ticket 16557
+	 */
+	public function test_pre_redirect_guess_404_permalink() {
+		// Test short-circuit filter.
+		add_filter(
+			'pre_redirect_guess_404_permalink',
+			function() {
+				return 'wp';
+			}
+		);
+		$this->go_to( '/child-page-1' );
+		$this->assertEquals( 'wp', redirect_guess_404_permalink() );
+	}
+
+	/**
+	 * @ticket 16557
+	 */
+	public function test_strict_redirect_guess_404_permalink() {
+		$post = self::factory()->post->create(
+			array(
+				'post_title' => 'strict-redirect-guess-404-permalink',
+			)
+		);
+
+		$this->go_to( 'strict-redirect' );
+
+		// Test default 'non-strict' redirect guess.
+		$this->assertEquals( get_permalink( $post ), redirect_guess_404_permalink() );
+
+		// Test 'strict' redirect guess.
+		add_filter( 'strict_redirect_guess_404_permalink', '__return_true' );
+		$this->assertFalse( redirect_guess_404_permalink() );
+	}
+
 	/**
 	 * @ticket 43745
 	 */