1last update Jan 2, 2002 (hackie@prohost.org/ilia@prohost.org) 2 3Shared 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 extension (sysvshm) written by Christian Cartus <cartus@atrior.de>, 8 unfortunately this extension was designed with PHP only in mind and 9 offers high level features which are extremely 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 extension to php for simple SHM operations, we were right :)). 13 14the functions are: 15 16int 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 identifier 30 31 32char 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 40int 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 48int 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 55int 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 63int shmop_close(int shmid) 64 65 shmid - shmid which to close 66 67 returns zero 68
