Mail Archives: cygwin/1997/11/12/16:31:28
In article <199711120808 DOT IAA08724 AT out4 DOT ibm DOT net>, <vischne AT ibm DOT net> wrote:
>This is probably a naive approach, but is the following code an accurate
>representation of how to implement fork() using the Windows 95 RTL C
>library? If so, how much effort would be needed to redo cygwin.dll so as
>to make fork() _not_ do anything to the cygwin environment?
>
>#include <stddef.h>
>#include <process.h>
>
>void __forker__(void *);
>unsigned long fork ()
>{
>/* Possible code for getting the return address of the fork() caller: */
> return _beginthread((_USERENTRY (*)(void *))forker,
> 4096, (void *)NULL);
>}
>
>void __forker__ (void *threadno)
>{
>/* Possible code for inserting the return address of the fork() caller: */
> return 0;
>}
This is a naive approach. It does not, in any way, duplicate the functionality
of fork. Sorry.
A forked process on UNIX runs as a separate process and does not share the
address space of the initiating process (unless we're talking about vfork
which is slightly different). Once a forked process has been started
it is a separate entity which can open new file handles and make changes
to memory without affecting the parent.
None of this is true for threads. And, think about it for a second.
A lot of people have worked on the cygwin code. Don't you think that it
is very likely that one of them would have stumbled across threads as
a mechanism for duplicating fork functionality if it was this trivially
easy?
--
http://www.bbc.com/ cgf AT bbc DOT com "Strange how unreal
VMS=>UNIX Solutions Boston Business Computing the real can be."
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