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/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
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*
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* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
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* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
#ifndef APR_SHM_H
#define APR_SHM_H
/**
* @file apr_shm.h
* @brief APR Shared Memory Routines
*/
#include "apr.h"
#include "apr_pools.h"
#include "apr_errno.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @defgroup apr_shm Shared Memory Routines
* @ingroup APR
* @{
*/
/**
* Private, platform-specific data struture representing a shared memory
* segment.
*/
typedef struct apr_shm_t apr_shm_t;
/**
* Create and make accessable a shared memory segment.
* @param m The shared memory structure to create.
* @param reqsize The desired size of the segment.
* @param filename The file to use for shared memory on platforms that
* require it.
* @param pool the pool from which to allocate the shared memory
* structure.
* @remark 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.
* @remark 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.
*
*/
APR_DECLARE(apr_status_t) apr_shm_create(apr_shm_t **m,
apr_size_t reqsize,
const char *filename,
apr_pool_t *pool);
/**
* Destroy a shared memory segment and associated memory.
* @param m The shared memory segment structure to destroy.
*/
APR_DECLARE(apr_status_t) apr_shm_destroy(apr_shm_t *m);
/**
* Attach to a shared memory segment that was created
* by another process.
* @param m The shared memory structure to create.
* @param filename The file used to create the original segment.
* (This MUST match the original filename.)
* @param pool the pool from which to allocate the shared memory
* structure for this process.
*/
APR_DECLARE(apr_status_t) apr_shm_attach(apr_shm_t **m,
const char *filename,
apr_pool_t *pool);
/**
* Detach from a shared memory segment without destroying it.
* @param m The shared memory structure representing the segment
* to detach from.
*/
APR_DECLARE(apr_status_t) apr_shm_detach(apr_shm_t *m);
/**
* Retrieve the base address of the shared memory segment.
* NOTE: This address is only usable within the callers address
* space, since this API does not guarantee that other attaching
* processes will maintain the same address mapping.
* @param m The shared memory segment from which to retrieve
* the base address.
*/
APR_DECLARE(void *) apr_shm_baseaddr_get(const apr_shm_t *m);
/**
* Retrieve the length of a shared memory segment in bytes.
* @param m The shared memory segment from which to retrieve
* the segment length.
*/
APR_DECLARE(apr_size_t) apr_shm_size_get(const apr_shm_t *m);
/**
* Get the pool used by this shared memory segment.
*/
APR_POOL_DECLARE_ACCESSOR(shm);
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* APR_SHM_T */
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