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Create and make accessable a shared memory segment. - Parameters:
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m |
The shared memory structure to create. |
reqsize |
The desired size of the segment. |
filename |
The file to use for shared memory on platforms that require it. |
pool |
the pool from which to allocate the shared memory structure. |
- Remarks:
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A note about Anonymous vs. Named shared memory segments: Not all plaforms support anonymous shared memory segments, but in some cases it is prefered over other types of shared memory implementations. Passing a NULL 'file' parameter to this function will cause the subsystem to use anonymous shared memory segments. If such a system is not available, APR_ENOTIMPL is returned.
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A note about allocation sizes: On some platforms it is necessary to store some metainformation about the segment within the actual segment. In order to supply the caller with the requested size it may be necessary for the implementation to request a slightly greater segment length from the subsystem. In all cases, the apr_shm_baseaddr_get() function will return the first usable byte of memory.
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