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last update sept 3, 2000 (slavapl@mailandnews.com/iliaa@home.com)
Shared Memory Operations Extension to PHP4
While developing a search deamon we needed the php based front end
to communicate the deamon via SHM. Now, PHP already had a shared memory
extention (sysvshm) written by Christian Cartus <cartus@atrior.de>,
unfortunatly this extention was designed with PHP only in mind, and
offers high level features which are extremly bothersome for basic SHM
we had in mind. After spending a day trying to reverse engeener figure
out the format of sysvshm we decided that it would be much easier to
add our own extention to php for simple SHM operations, we were right :)).
the functions are:
int shm_open(int key, string flags, int mode, int size)
key - the key of/for the shared memory block
flags - 2 flags are avalible
a for access (sets IPC_EXCL)
c for create (sets IPC_CREATE)
mode - acsess mode same as for a file (0644) for example
size - size of the block in bytes
returns an indentifier
char shm_read(int shmid, int start, int count)
shmid - shmid from which to read
start - offset from which to start reading
count - how many bytes to read
returns the data read
int shm_write(int shmid, string data, int offset)
shmid - shmid from which to read
data - string to put into shared memory
offset - offset in shm to write from
returns bytes written
int shm_size(int shmid)
shmid - shmid for which to return the size
returns the size in bytes of the shm segment
int shm_delete(int shmid)
marks the segment for deletion, the segment will be deleted when all processes mapping it will detach
shmid - shmid which to mark for deletion
returns 1 if all ok, zero on failure
int shm_close(int shmid)
shmid - shmid which to close
returns zero
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