Multiple changes.
Multiple changes.

Changed write to in and read to out in circular_buffer_s struct.

buf_init now creates a circular buffer instead of just a shared memory
segment by initializing its fields.

buf_destroy implemented.
This function detaches the shared memory segment from the address space
of the calling process and subsequently marks it to be destroyed.

More minor changes.

paraschas/ce121-a4,paraschas/ce121-a4,paraschas/ce121-a4