WP_REST_Posts_Controller::get_item_permissions_check

	public function get_item_permissions_check( $request ) {
		$post = $this->get_post( $request['id'] );
		if ( is_wp_error( $post ) ) {
			return $post;
		}

		if ( 'edit' === $request['context'] && $post && ! $this->check_update_permission( $post ) ) {
			return new WP_Error(
				'rest_forbidden_context',
				__( 'Sorry, you are not allowed to edit this post.' ),
				array( 'status' => rest_authorization_required_code() )
			);
		}

		if ( $post && ! empty( $request['password'] ) ) {
			// Check post password, and return error if invalid.
			if ( ! hash_equals( $post->post_password, $request['password'] ) ) {
				return new WP_Error(
					'rest_post_incorrect_password',
					__( 'Incorrect post password.' ),
					array( 'status' => 403 )
				);
			}
		}

		// Allow access to all password protected posts if the context is edit.
		if ( 'edit' === $request['context'] ) {
			add_filter( 'post_password_required', '__return_false' );
		}

		if ( $post ) {
			return $this->check_read_permission( $post );
		}

		return true;
	}