RtlAppendStringToString

INT64 __fastcall RtlAppendStringToString(_STRING *Destination, const _STRING *Source){
  int Length; 
  __int64 v4; 
  Length = Source->Length;
  if( !(_WORD)Length )
    return 0i64;
  v4 = Destination->Length;
  if( (int)v4 + Length <= (unsigned int)Destination->MaximumLength )
  {
    memmove((UINT8 *)&Destination->Buffer[v4], (UINT8 *)Source->Buffer, Source->Length);
    Destination->Length += Length;
    return 0i64;
  }
  return 3221225507i64;
}

Referenced by:

CmpFlushBackupHive
CmpInitBackupHive
CmpLoadHiveThread
EmInitSystem
MiFormFullImageName