Codechange: add method for reading a string from a savegame given a length

src/saveload/saveload.cpp

@@ -928,6 +928,18 @@ static void FixSCCEncoded(std::string &str)
 	}
 }
 
+/**
+ * Read the given amount of bytes from the buffer into the string.
+ * @param str The string to write to.
+ * @param length The amount of bytes to read into the string.
+ * @note Does not perform any validation on validity of the string.
+ */
+void SlReadString(std::string &str, size_t length)
+{
+	str.resize(length);
+	SlCopyBytes(str.data(), length);
+}
+
 /**
  * Save/Load a \c std::string.
  * @param ptr the string being manipulated
@@ -953,8 +965,7 @@ static void SlStdString(void *ptr, VarType conv)
 				return;
 			}
 
-			str->resize(len);
+			SlReadString(*str, len);
-			SlCopyBytes(str->data(), len);
 
 			StringValidationSettings settings = SVS_REPLACE_WITH_QUESTION_MARK;
 			if ((conv & SLF_ALLOW_CONTROL) != 0) {

src/saveload/saveload.h

@@ -1328,6 +1328,7 @@ size_t SlCalcObjMemberLength(const void *object, const SaveLoad &sld);
 size_t SlCalcObjLength(const void *object, const SaveLoadTable &slt);
 
 uint8_t SlReadByte();
+void SlReadString(std::string &str, size_t length);
 void SlWriteByte(uint8_t b);
 
 void SlGlobList(const SaveLoadTable &slt);