cygwin.dll src question: fork()

Tim Newsham
Thu Oct 30 00:48:00 GMT 1997

> >At the time when cygwin_fork_helper1() returns isn't the
> >child's state already a copy of the parent's state?
> No, actually, it isn't.  The setjmp and longjmp are used to move the
> current execution point into the appropriate point in the cygwin_fork_helper1
> function to emulate a true UNIX fork().
> What happens is that to emulate a fork, the parent process starts the
> extends the stack to hopefully insure that the stack is large enough to
> duplicate the parent, and longjmps to the child portion of the
> cygwin_fork_helper1 routine.  There it wakes up the parent and sleeps
> itself.

um..  this is a completely different setjmp/longjmp pair.
The setjmp that is jumped to from crt0 is in the cygwin_fork_helper1()
function.  The __fork() function has its own setjmp/longjmp
pair that seems to add no extra functionality.  Perhaps some sort
of legacy from fork implementations of past.

>			"Strange how unreal

                                             Tim N.
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