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70 lines
2.1 KiB
Plaintext
70 lines
2.1 KiB
Plaintext
last update Jan 2, 2002 (hackie@prohost.org/ilia@prohost.org)
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Shared Memory Operations Extension to PHP
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While developing a search deamon we needed a php based front end
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to communicate the deamon via SHM. PHP already had a shared memory
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extention (sysvshm) written by Christian Cartus <cartus@atrior.de>,
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unfortunatly this extention was designed with PHP only in mind and
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offers high level features which are extremly bothersome for basic SHM
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we had in mind. After spending a day trying to reverse engineer and figure
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out the format of sysvshm we decided that it would be much easier to
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add our own extention to php for simple SHM operations, we were right :)).
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the functions are:
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int shmop_open(int key, string flags, int mode, int size)
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key - the key of/for the shared memory block
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flags - 4 flags are avalible
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a for read only access (sets SHM_RDONLY)
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w for read & write access
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c create or open an existing segment (sets IPC_CREATE)
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n create a new segment and fail if one already exists under same name (sets IPC_CREATE|IPC_EXCL)
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(the n flag is mostly useful for security perpouses, so that you don't end up opening a faked segment
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if someone guesses your key)
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mode - acsess mode same as for a file (0644) for example
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size - size of the block in bytes
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returns an indentifier
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char shmop_read(int shmid, int start, int count)
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shmid - shmid from which to read
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start - offset from which to start reading
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count - how many bytes to read
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returns the data read
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int shmop_write(int shmid, string data, int offset)
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shmid - shmid from which to read
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data - string to put into shared memory
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offset - offset in shm to write from
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returns bytes written
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int shmop_size(int shmid)
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shmid - shmid for which to return the size
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returns the size in bytes of the shm segment
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int shmop_delete(int shmid)
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marks the segment for deletion, the segment will be deleted when all processes mapping it will detach
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shmid - shmid which to mark for deletion
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returns 1 if all ok, zero on failure
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int shmop_close(int shmid)
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shmid - shmid which to close
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returns zero
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