278 lines
9.4 KiB
C
278 lines
9.4 KiB
C
/****************************************************************************
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* mm/shm/shmctl.c
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*
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* Copyright (C) 2014 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/shm.h>
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#include <sys/ipc.h>
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#include <unistd.h>
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#include <string.h>
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#include <semaphore.h>
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#include <time.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/mm/shm.h>
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#include <nuttx/pgalloc.h>
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#include "shm/shm.h"
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#ifdef CONFIG_MM_SHM
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: shmctl
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*
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* Description:
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* The shmctl() function provides a variety of shared memory control
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* operations as specified by cmd. The following values for cmd are
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* available:
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*
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* - IPC_STAT
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* Place the current value of each member of the shmid_ds data
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* structure associated with shmid into the structure pointed to by
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* buf.
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* - IPC_SET
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* Set the value of the shm_perm.mode member of the shmid_ds data
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* structure associated with shmid to the corresponding value found
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* in the structure pointed to by buf.
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* - IPC_RMID
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* Remove the shared memory identifier specified by shmid from the
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* system and destroy the shared memory segment and shmid_ds data
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* structure associated with it.
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*
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* Input Parameters:
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* shmid - Shared memory identifier
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* cmd - shmctl() command
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* buf - Data associated with the shmctl() command
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*
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* Returned Value:
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* Upon successful completion, shmctl() will return 0; otherwise, it will
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* return -1 and set errno to indicate the error.
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*
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* - EACCES
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* The argument cmd is equal to IPC_STAT and the calling process does
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* not have read permission.
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* - EINVAL
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* The value of shmid is not a valid shared memory identifier, or the
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* value of cmd is not a valid command.
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* - EPERM
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* The argument cmd is equal to IPC_RMID or IPC_SET and the effective
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* user ID of the calling process is not equal to that of a process
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* with appropriate privileges and it is not equal to the value of
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* shm_perm.cuid or shm_perm.uid in the data structure associated with
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* shmid.
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* - EOVERFLOW
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* The cmd argument is IPC_STAT and the gid or uid value is too large
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* to be stored in the structure pointed to by the buf argument.
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*
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* POSIX Deviations:
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* - IPC_SET. Does not set the the shm_perm.uid or shm_perm.gid
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* members of the shmid_ds data structure associated with shmid
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* because user and group IDs are not yet supported by NuttX
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* - IPC_SET. Does not restrict the operation to processes with
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* appropriate privileges or matching user IDs in shmid_ds data
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* structure associated with shmid. Again because user IDs and
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* user/group privileges are are not yet supported by NuttX
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* - IPC_RMID. Does not restrict the operation to processes with
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* appropriate privileges or matching user IDs in shmid_ds data
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* structure associated with shmid. Again because user IDs and
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* user/group privileges are are not yet supported by NuttX
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*
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****************************************************************************/
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int shmctl(int shmid, int cmd, struct shmid_ds *buf)
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{
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FAR struct shm_region_s *region;
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int ret;
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DEBUGASSERT(shmid >= 0 && shmid < CONFIG_ARCH_SHM_MAXREGIONS);
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region = &g_shminfo.si_region[shmid];
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DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
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/* Get exclusive access to the region data structure */
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ret = sem_wait(®ion->sr_sem);
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if (ret < 0)
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{
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shmdbg("sem_wait failed: %d\n", ret);
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return ret;
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}
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/* Handle the request according to the received cmd */
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switch (cmd)
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{
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case IPC_STAT:
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{
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/* Place the current value of each member of the shmid_ds data
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* structure associated with shmid into the structure pointed to
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* by buf.
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*/
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DEBUGASSERT(buf);
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memcpy(buf, ®ion->sr_ds, sizeof(struct shmid_ds));
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}
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break;
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case IPC_SET:
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{
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/* Set the value of the shm_perm.mode member of the shmid_ds
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* data structure associated with shmid to the corresponding
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* value found in the structure pointed to by buf.
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*/
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region->sr_ds.shm_perm.mode = buf->shm_perm.mode;
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}
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break;
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case IPC_RMID:
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{
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/* Are any processes attached to the region? */
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if (region->sr_ds.shm_nattch > 0)
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{
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/* Yes.. just set the UNLINKED flag. The region will be removed when there are no longer any processes attached to it.
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*/
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region->sr_flags |= SRFLAG_UNLINKED;
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}
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else
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{
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/* No.. free the entry now */
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shm_destroy(shmid);
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/* Don't try anything further on the deleted region */
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return OK;
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}
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}
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break;
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default:
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shmdbg("Unrecognized command: %d\n", cmd);
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ret = -EINVAL;
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goto errout_with_semaphore;
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}
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/* Save the process ID of the the last operation */
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region = &g_shminfo.si_region[shmid];
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region->sr_ds.shm_lpid = getpid();
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/* Save the time of the last shmctl() */
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region->sr_ds.shm_ctime = time(NULL);
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/* Release our lock on the entry */
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sem_post(®ion->sr_sem);
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return ret;
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errout_with_semaphore:
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sem_post(®ion->sr_sem);
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set_errno(-ret);
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return ERROR;
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}
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/****************************************************************************
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* Name: shm_destroy
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*
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* Description:
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* Destroy a memory region. This function is called:
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*
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* - On certain conditions when shmget() is not successful in instantiating
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* the full memory region and we need to clean up and free a table entry.
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* - When shmctl() is called with cmd == IPC_RMID and there are no
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* processes attached to the memory region.
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* - When shmdt() is called after the last process detaches from memory
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* region after it was previously marked for deletion by shmctl().
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*
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* Input Parameters:
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* shmid - Shared memory identifier
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*
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* Returned Value:
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* None
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*
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* Assumption:
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* The caller holds either the region table semaphore or else the
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* semaphore on the particular entry being deleted.
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*
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****************************************************************************/
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void shm_destroy(int shmid)
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{
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FAR struct shm_region_s *region = &g_shminfo.si_region[shmid];
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int i;
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/* Free all of the allocated physical pages */
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for (i = 0; i < CONFIG_ARCH_SHM_NPAGES && region->sr_pages[i] != 0; i++)
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{
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mm_pgfree(region->sr_pages[i], 1);
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}
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/* Reset the region entry to its initial state */
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sem_destroy(®ion->sr_sem);
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memset(region, 0, sizeof(struct shm_region_s));
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}
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#endif /* CONFIG_MM_SHM */
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