[GSOC] System V IPC in userspace week5 report

grigore larisa larisagrigore at gmail.com
Sun Jul 21 14:17:31 PDT 2013

Hi all,

This week I've changed the shared memory approach according to Samuel and
Markus feedback. For each ipc resource, the daemon creates a file in a
known directory, open it and installs a file descriptor in the client files
table. After the daemon open its, it does a *unlink()* call (as Samuel
suggested) such as no other process can access it.
*shmat* is done using *mmap* call and the daemon is announced in order to
update some data. I have discussed with Markus about the case a process
bypasses the API and calls directly *mmap* instead of *shmat*. A way of
resolving this problem is to use *kevents* and add another type
of EVFILT_VNODE events (for mmap and munmap).
*shmctl* is implementing by exchanging data with the daemon.
In the last part of the week I have studied the semaphores kernel
implementation and made a plan for the userland approach.

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