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Annotation of embedaddon/php/ext/shmop/README, revision 1.1

1.1     ! misho       1: last update Jan 2, 2002 (hackie@prohost.org/ilia@prohost.org)
        !             2: 
        !             3: Shared Memory Operations Extension to PHP
        !             4: 
        !             5:        While developing a search deamon we needed a php based front end
        !             6:        to communicate the deamon via SHM. PHP already had a shared memory
        !             7:        extention (sysvshm) written by Christian Cartus <cartus@atrior.de>,
        !             8:        unfortunatly this extention was designed with PHP only in mind and
        !             9:        offers high level features which are extremly bothersome for basic SHM
        !            10:        we had in mind.  After spending a day trying to reverse engineer and figure
        !            11:        out the format of sysvshm we decided that it would be much easier to
        !            12:        add our own extention to php for simple SHM operations, we were right :)). 
        !            13: 
        !            14: the functions are:
        !            15:        
        !            16: int shmop_open(int key, string flags, int mode, int size)
        !            17:        
        !            18:        key             - the key of/for the shared memory block
        !            19:        flags           - 4 flags are avalible 
        !            20:                                a for read only access (sets SHM_RDONLY)
        !            21:                                w for read & write access
        !            22:                                c create or open an existing segment (sets IPC_CREATE)
        !            23:                                n create a new segment and fail if one already exists under same name (sets IPC_CREATE|IPC_EXCL)
        !            24:                                (the n flag is mostly useful for security perpouses, so that you don't end up opening a faked segment 
        !            25:                                if someone guesses your key)
        !            26:        mode            - acsess mode same as for a file (0644) for example
        !            27:        size            - size of the block in bytes
        !            28:        
        !            29:        returns an indentifier
        !            30:        
        !            31: 
        !            32: char shmop_read(int shmid, int start, int count)
        !            33: 
        !            34:        shmid           - shmid from which to read
        !            35:        start           - offset from which to start reading
        !            36:        count           - how many bytes to read
        !            37:        
        !            38:        returns the data read
        !            39: 
        !            40: int shmop_write(int shmid, string data, int offset)
        !            41: 
        !            42:        shmid           - shmid from which to read
        !            43:        data            - string to put into shared memory
        !            44:        offset          - offset in shm to write from
        !            45:        
        !            46:        returns bytes written
        !            47:        
        !            48: int shmop_size(int shmid)
        !            49: 
        !            50:        shmid           - shmid for which to return the size
        !            51:        
        !            52:        returns the size in bytes of the shm segment
        !            53:        
        !            54:        
        !            55: int shmop_delete(int shmid)
        !            56: 
        !            57:        marks the segment for deletion, the segment will be deleted when all processes mapping it will detach
        !            58: 
        !            59:        shmid           - shmid which to mark for deletion
        !            60:        
        !            61:        returns 1 if all ok, zero on failure
        !            62:        
        !            63: int shmop_close(int shmid)
        !            64: 
        !            65:        shmid           - shmid which to close
        !            66:        
        !            67:        returns zero
        !            68:        
        !            69: