Still trouble with IPC/cygipc

Charles Wilson cygwin@cwilson.fastmail.fm
Sat Feb 14 15:31:00 GMT 2004


Frank Wuebbeling wrote:
> Hi,
> 
> I'm still having trouble understanding how IPC is supposed to be working now. I
> used to be running apache 2.0, but that fails now due to lots of IPC problems.
> cygcheck tells me my installation has cygipc version 2.03-2, cygwin is at
> 1.5.7-1, and yes, I reinstalled cygwin after installing cygipc so that my
> include files point to the new ipc distribution. 

No, that means you now have:
   /usr/include/sys/ipc.h        <<< from cygwin
   /usr/include/cygipc/sys/ipc.h <<< from cygipc
Which is good, right, and proper.

 From /usr/share/doc/Cygwin/cygipc-*.README, you need to
   1) compile with -I/usr/include/cygipc
   2) link with -lcygipc

If you don't do #1, you end up with cygwin/cygserver's declarations.  If 
you don't do #2, you end up with cygwin/cygserver's implementations.

> ipcs then gives me
> 
> wuebbel% ipcs
> Bad system call

And finally, ipcs is the cygwin/cygserver version.  You want ipcscygipc. 
  (you did upgrade cygutils to 1.2.4-1, right?  And then re-installed 
cygwin-1.5.7 AGAIN after doing so?)

> just like any call to shmget as in:
> 
> #include <sys/ipc.h>
> #include <sys/shm.h>
> main()
> {
>  printf("%d\n",shmget(1,10,IPC_CREAT|IPC_PRIVATE));
> }
> wuebbel% cc x.c
> wuebbel% a.exe
> Bad system call

Yep, you're using cygwin's routines, which expect that cygserver is 
running.  It's not, so that's a "bad system call."

Or, you could bail on cygipc and just use cygserver instead.  Crank up 
the cygserver daemon (see /usr/share/doc/cygserver* ? I think...) and 
try your tests again.

> 
> cygcheck(edited):

In the future, do not paste the cygcheck output but rather attach it. 
That way, it won't clog the search engine results with false hits for 
"XFree86" etc.

--
Chuck


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