sockets and fds

Hello friends, I have a couple of questions about sockets and file descriptors. In my extension I make use of a ordinary c socket and two fds build on it. I want this connection to be kept over request, therefore I put a struct pointer containing this into the persistant_list of the zend engine. I made it like the mysql extension, which is looking for an already opened connection by zend_hash_find(). If a connection already exists, it will be used, if not, a new connection struct is malloced (not emalloc()) and inserted into a new list_entry, which is immediately hashed into the persistand list. As key I use a emalloced string, consisting of a prefix and the session id, since I need to map sessions to connections. I've also implement a zend_list_destructor for a persistent resource, actual the allocated conn. struct. There the items of the struct will be freed by fclose(), close() and at last the whole struct by free(). The exported extension functions are calling sometimes not exported functions, which are not introduced by the function list macro. This functions do some not-zend-related-stuff, but make use of the allocated connection. The initialization of the connection succeed, the functions in the same request are working how I want them to, but the explicitly closing of the connection causes a segfault. If a new request attempts to reuse the connection, the fds are lost, respectively the connection struct pointer seems to be invalid -> segfault. Now my questions: 1. Is there anything to know about using standart c sockets and fds within php extensions? 2. Do pointers stay valid over request end, if they're malloced (not emalloc())? 3. Should anything be considered about additional c functions, which not exported? (if at all...) I am not experienced with threads, therefore I might have forget some details...about allocations in threads an so on... Good night and best regards Ron