add some UTF-8 validation

src/item/Item.php

@@ -45,6 +45,7 @@ use pocketmine\nbt\tag\StringTag;
 use pocketmine\nbt\TreeRoot;
 use pocketmine\player\Player;
 use pocketmine\utils\Binary;
+use pocketmine\utils\Utils;
 use function base64_decode;
 use function base64_encode;
 use function get_class;
@@ -163,7 +164,7 @@ class Item implements \JsonSerializable{
 	 * @return $this
 	 */
 	public function setCustomName(string $name) : Item{
-		//TODO: encoding might need to be checked here
+		Utils::checkUTF8($name);
 		$this->customName = $name;
 		return $this;
 	}
@@ -193,6 +194,7 @@ class Item implements \JsonSerializable{
 			if(!is_string($line)){
 				throw new \TypeError("Expected string[], but found " . gettype($line) . " in given array");
 			}
+			Utils::checkUTF8($line);
 		}
 		$this->lore = $lines;
 		return $this;

src/item/WritableBookPage.php

@@ -23,6 +23,8 @@ declare(strict_types=1);
 
 namespace pocketmine\item;
 
+use pocketmine\utils\Utils;
+
 class WritableBookPage{
 
 	/** @var string */
@@ -31,7 +33,8 @@ class WritableBookPage{
 	private $photoName;
 
 	public function __construct(string $text, string $photoName = ""){
-		//TODO: data validation, encoding checks
+		//TODO: data validation
+		Utils::checkUTF8($text);
 		$this->text = $text;
 		$this->photoName = $photoName;
 	}

src/item/WrittenBook.php

@@ -24,6 +24,7 @@ declare(strict_types=1);
 namespace pocketmine\item;
 
 use pocketmine\nbt\tag\CompoundTag;
+use pocketmine\utils\Utils;
 
 class WrittenBook extends WritableBookBase{
 
@@ -92,6 +93,7 @@ class WrittenBook extends WritableBookBase{
 	 * @return $this
 	 */
 	public function setAuthor(string $authorName) : self{
+		Utils::checkUTF8($authorName);
 		$this->author = $authorName;
 		return $this;
 	}
@@ -113,6 +115,7 @@ class WrittenBook extends WritableBookBase{
 	 * @return $this
 	 */
 	public function setTitle(string $title) : self{
+		Utils::checkUTF8($title);
 		$this->title = $title;
 		return $this;
 	}