cygipc does not seem to work!!!

Brian Michael Genisio
Tue Jun 19 12:33:00 GMT 2001

Hello Cygwin people,

I am trying to get a very simple shared memory application to work.  It works
find in linux and solaris, but in cygwin... no luck.

I create the memory and attach to it with :
shmid = shmget(IPC_PRIVATE, 100, IPC_CREAT|0777);
strp = (char *)shmat(shmid, 0, 0);

The other app gets the shmid through stdout, and through a command arg.  It
opens it with :
strp = (char *)shmat(shmid, 0, 0);

The problem is that the second application cannot open the shared memory until
the first application has terminated!!!  Once it does, it can read the memory
with no problem.  Unfortunately, it is difficult for them to communicate when
the first program has already exited.

I have tested it by starting the creator program, and running ipcs.  ipcs does
not recognize the memory either, until the program has exited.

Any ideas?  Has anyone else gotten it to work?  Shared memory isnt that
difficult... and I am not sure why I am having this problem.


      \\|//   Brian Genisio
      (o o)

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