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Annotation of embedaddon/php/ext/shmop/README, revision 1.1.1.2

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
1.1.1.2 ! misho       7:        extension (sysvshm) written by Christian Cartus <cartus@atrior.de>,
        !             8:        unfortunately this extension was designed with PHP only in mind and
1.1       misho       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
1.1.1.2 ! misho      12:        add our own extension to php for simple SHM operations, we were right :)). 
1.1       misho      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: