fork semantics

[Terry Lambert]

Petri Helenius wrote:
> Could somebody point me how fork is wrapped/implemented with libkse ?

http://www.opengroup.org/onlinepubs/007904975/nfindex.html

> Do all threads get duplicated and which would be the recommended way to
> spin something off hanging on a pipe talking to one of the threads already in
> existence?

	"A process shall be created with a single thread. If a
	 multi-threaded process calls fork(), the new process shall
	 contain a replica of the calling thread and its entire
	 address space, possibly including the states of mutexes
	 and other resources. Consequently, to avoid errors, the
	 child process may only execute async-signal-safe
	 operations until such time as one of the exec functions
	 is called. [THR]   Fork handlers may be established by
	 means of the pthread_atfork() function in order to
	 maintain application invariants across fork() calls. 

         When the application calls fork() from a signal handler
	 and any of the fork handlers registered by pthread_atfork()
         calls a function that is not asynch-signal-safe, the
	 behavior is undefined."

-- Terry