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/* Copyright 2000-2005 The Apache Software Foundation or its licensors, as
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* @brief APR Shared Memory Routines
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#include "apr_pools.h"
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#include "apr_errno.h"
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#endif /* __cplusplus */
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* @defgroup apr_shm Shared Memory Routines
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* Private, platform-specific data struture representing a shared memory
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typedef struct apr_shm_t apr_shm_t;
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* Create and make accessable a shared memory segment.
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* @param m The shared memory structure to create.
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* @param reqsize The desired size of the segment.
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* @param filename The file to use for shared memory on platforms that
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* @param pool the pool from which to allocate the shared memory
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* @remark A note about Anonymous vs. Named shared memory segments:
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* Not all plaforms support anonymous shared memory segments, but in
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* some cases it is prefered over other types of shared memory
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* implementations. Passing a NULL 'file' parameter to this function
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* will cause the subsystem to use anonymous shared memory segments.
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* If such a system is not available, APR_ENOTIMPL is returned.
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* @remark A note about allocation sizes:
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* On some platforms it is necessary to store some metainformation
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* about the segment within the actual segment. In order to supply
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* the caller with the requested size it may be necessary for the
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* implementation to request a slightly greater segment length
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* from the subsystem. In all cases, the apr_shm_baseaddr_get()
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* function will return the first usable byte of memory.
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APR_DECLARE(apr_status_t) apr_shm_create(apr_shm_t **m,
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* Remove shared memory segment associated with a filename.
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* @param filename The filename associated with shared-memory segment which
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* @param pool The pool used for file operations
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* @remark This function is only supported on platforms which support
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* name-based shared memory segments, and will return APR_ENOTIMPL on
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* platforms without such support.
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APR_DECLARE(apr_status_t) apr_shm_remove(const char *filename,
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* Destroy a shared memory segment and associated memory.
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* @param m The shared memory segment structure to destroy.
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APR_DECLARE(apr_status_t) apr_shm_destroy(apr_shm_t *m);
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* Attach to a shared memory segment that was created
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* @param m The shared memory structure to create.
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* @param filename The file used to create the original segment.
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* (This MUST match the original filename.)
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* @param pool the pool from which to allocate the shared memory
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* structure for this process.
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APR_DECLARE(apr_status_t) apr_shm_attach(apr_shm_t **m,
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const char *filename,
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* Detach from a shared memory segment without destroying it.
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* @param m The shared memory structure representing the segment
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APR_DECLARE(apr_status_t) apr_shm_detach(apr_shm_t *m);
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* Retrieve the base address of the shared memory segment.
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* NOTE: This address is only usable within the callers address
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* space, since this API does not guarantee that other attaching
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* processes will maintain the same address mapping.
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* @param m The shared memory segment from which to retrieve
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* @return address, aligned by APR_ALIGN_DEFAULT.
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APR_DECLARE(void *) apr_shm_baseaddr_get(const apr_shm_t *m);
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* Retrieve the length of a shared memory segment in bytes.
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* @param m The shared memory segment from which to retrieve
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* the segment length.
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APR_DECLARE(apr_size_t) apr_shm_size_get(const apr_shm_t *m);
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* Get the pool used by this shared memory segment.
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APR_POOL_DECLARE_ACCESSOR(shm);
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#endif /* APR_SHM_T */