Re: [PHP4BETA] Questions on sem_* and shm_* functions

SB>>   - What is the perm argument of sem_get() and shm_attach() for? Is
SB>>     this, too, needed to be emulated?

For shmget that's permissions. Manual says this:

       mode_flags (lowest 9 bits)
                   specifying  the  permissions  granted  to  the
                   owner,  group, and world.  Presently, the exe-
                   cute permissions are not used by the system.

SB>>   - What does shm_attach() return if for some reason the creation or
SB>>     opening of a shared memory segment fails? Although it is unlikely
SB>>     that this may happen with nmy fake shared memory implementation, as
SB>>     the variables are held in a SQL table instead of RAM.

From the code I see it returns false on failure.

SB>>   - Is it true that shm_detach() only removes the shm_identifier for a
SB>>     shared memory segment from some sort of list but doesn't remove the
SB>>     stored variables of that segement?

Not exactly. If reference count for this segment for the script reaches 0,
it calls shmdt, detaching this segment.

SB>>   - How do the functions shm_get_var() and shm_remove_var() behave if
SB>>     the given shared memory segment and / or variable doesn't exist?

They return false and issue warning.

SB>>   - How do the functions shm_detach() and shm_remove() behave if
SB>>     the given shared memory segment doesn't exist?

shm_detach have no checks. _remove returns false on error.

SB>>   - How do the functions sem_acquire() and sem_release() behave if the
SB>>     given semaphore doesn't exist?

They return false and print warning if something bad happens.
-- 
Stanislav Malyshev   [email protected]          
+972-3-6139665