Merge #3532

3532: Fix crash on namechange (fixes #3444) r=heinrich5991 a=def-

<!-- What is the motivation for the changes of this pull request -->

## Checklist

- [x] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [x] Tested in combination with possibly related configuration options
- [x] Written a unit test if it works standalone, system.c especially
- [x] Considered possible null pointers and out of bounds array indexing
- [x] Changed no physics that affect existing maps
- [x] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: def <dennis@felsin9.de>

src/game/client/components/menus.cpp

@@ -631,7 +631,7 @@ int CMenus::DoEditBox(void *pID, const CUIRect *pRect, char *pStr, unsigned StrS
 			if(Text)
 			{
 				int Offset = str_length(pStr);
-				int CharsLeft = StrSize - Offset - 1;
+				int CharsLeft = StrSize - Offset;
 				char *pCur = pStr + Offset;
 				str_utf8_copy(pCur, Text, CharsLeft);
 				for(int i = 0; i < CharsLeft; i++)

src/test/str.cpp

@@ -217,6 +217,8 @@ TEST(Str, StrCopyNum)
 	EXPECT_STREQ(aBuf, "Foobar");
 	str_utf8_truncate(aBuf, sizeof(aBuf), foo, 7);
 	EXPECT_STREQ(aBuf, "Foobaré");
+	str_utf8_truncate(aBuf, sizeof(aBuf), foo, 0);
+	EXPECT_STREQ(aBuf, "");
 
 	char aBuf2[8];
 	str_utf8_truncate(aBuf2, sizeof(aBuf2), foo, 7);

src/test/thread.cpp

@@ -79,4 +79,5 @@ TEST(Thread, Lock)
 	void *pThread = thread_init(LockThread, &Lock, "lock");
 	lock_unlock(Lock);
 	thread_wait(pThread);
+	lock_destroy(Lock);
 }