nuttx/mm/shm/shmctl.c
zhangshoukui 8e4e09be2d shm: The limits have been made in Make.defs and remove useless macro in code
ifeq ($(CONFIG_MM_SHM),y)
CSRCS += shmat.c shmctl.c shmdt.c shmget.c

DEPPATH += --dep-path shm
VPATH += :shm
endif

Signed-off-by: zhangshoukui <zhangshoukui@xiaomi.com>
2024-09-18 13:42:11 +08:00

250 lines
8.0 KiB
C

/****************************************************************************
* mm/shm/shmctl.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/shm.h>
#include <sys/ipc.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/sched.h>
#include <nuttx/pgalloc.h>
#include "shm/shm.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: shmctl
*
* Description:
* The shmctl() function provides a variety of shared memory control
* operations as specified by cmd. The following values for cmd are
* available:
*
* - IPC_STAT
* Place the current value of each member of the shmid_ds data
* structure associated with shmid into the structure pointed to by
* buf.
* - IPC_SET
* Set the value of the shm_perm.mode member of the shmid_ds data
* structure associated with shmid to the corresponding value found
* in the structure pointed to by buf.
* - IPC_RMID
* Remove the shared memory identifier specified by shmid from the
* system and destroy the shared memory segment and shmid_ds data
* structure associated with it.
*
* Input Parameters:
* shmid - Shared memory identifier
* cmd - shmctl() command
* buf - Data associated with the shmctl() command
*
* Returned Value:
* Upon successful completion, shmctl() will return 0; otherwise, it will
* return -1 and set errno to indicate the error.
*
* - EACCES
* The argument cmd is equal to IPC_STAT and the calling process does
* not have read permission.
* - EINVAL
* The value of shmid is not a valid shared memory identifier, or the
* value of cmd is not a valid command.
* - EPERM
* The argument cmd is equal to IPC_RMID or IPC_SET and the effective
* user ID of the calling process is not equal to that of a process
* with appropriate privileges and it is not equal to the value of
* shm_perm.cuid or shm_perm.uid in the data structure associated with
* shmid.
* - EOVERFLOW
* The cmd argument is IPC_STAT and the gid or uid value is too large
* to be stored in the structure pointed to by the buf argument.
*
* POSIX Deviations:
* - IPC_SET. Does not set the shm_perm.uid or shm_perm.gid
* members of the shmid_ds data structure associated with shmid
* because user and group IDs are not yet supported by NuttX
* - IPC_SET. Does not restrict the operation to processes with
* appropriate privileges or matching user IDs in shmid_ds data
* structure associated with shmid. Again because user IDs and
* user/group privileges are are not yet supported by NuttX
* - IPC_RMID. Does not restrict the operation to processes with
* appropriate privileges or matching user IDs in shmid_ds data
* structure associated with shmid. Again because user IDs and
* user/group privileges are are not yet supported by NuttX
*
****************************************************************************/
int shmctl(int shmid, int cmd, struct shmid_ds *buf)
{
FAR struct shm_region_s *region;
int ret;
DEBUGASSERT(shmid >= 0 && shmid < CONFIG_ARCH_SHM_MAXREGIONS);
region = &g_shminfo.si_region[shmid];
DEBUGASSERT((region->sr_flags & SRFLAG_INUSE) != 0);
/* Get exclusive access to the region data structure */
ret = nxmutex_lock(&region->sr_lock);
if (ret < 0)
{
shmerr("ERROR: nxsem_wait failed: %d\n", ret);
goto errout_with_ret;
}
/* Handle the request according to the received cmd */
switch (cmd)
{
case IPC_STAT:
{
/* Place the current value of each member of the shmid_ds data
* structure associated with shmid into the structure pointed to
* by buf.
*/
DEBUGASSERT(buf);
memcpy(buf, &region->sr_ds, sizeof(struct shmid_ds));
}
break;
case IPC_SET:
{
/* Set the value of the shm_perm.mode member of the shmid_ds
* data structure associated with shmid to the corresponding
* value found in the structure pointed to by buf.
*/
region->sr_ds.shm_perm.mode = buf->shm_perm.mode;
}
break;
case IPC_RMID:
{
/* Are any processes attached to the region? */
if (region->sr_ds.shm_nattch > 0)
{
/* Yes.. just set the UNLINKED flag. The region will be
* removed when there are no longer any processes attached to
* it.
*/
region->sr_flags |= SRFLAG_UNLINKED;
}
else
{
/* No.. free the entry now */
shm_destroy(shmid);
/* Don't try anything further on the deleted region */
return OK;
}
}
break;
default:
shmerr("ERROR: Unrecognized command: %d\n", cmd);
ret = -EINVAL;
goto errout_with_lock;
}
/* Save the process ID of the last operation */
region = &g_shminfo.si_region[shmid];
region->sr_ds.shm_lpid = _SCHED_GETPID();
/* Save the time of the last shmctl() */
region->sr_ds.shm_ctime = time(NULL);
/* Release our lock on the entry */
nxmutex_unlock(&region->sr_lock);
return ret;
errout_with_lock:
nxmutex_unlock(&region->sr_lock);
errout_with_ret:
set_errno(-ret);
return ERROR;
}
/****************************************************************************
* Name: shm_destroy
*
* Description:
* Destroy a memory region. This function is called:
*
* - On certain conditions when shmget() is not successful in instantiating
* the full memory region and we need to clean up and free a table entry.
* - When shmctl() is called with cmd == IPC_RMID and there are no
* processes attached to the memory region.
* - When shmdt() is called after the last process detaches from memory
* region after it was previously marked for deletion by shmctl().
*
* Input Parameters:
* shmid - Shared memory identifier
*
* Returned Value:
* None
*
* Assumption:
* The caller holds either the region table mutex or else the
* mutex on the particular entry being deleted.
*
****************************************************************************/
void shm_destroy(int shmid)
{
FAR struct shm_region_s *region = &g_shminfo.si_region[shmid];
int i;
/* Free all of the allocated physical pages */
for (i = 0; i < CONFIG_ARCH_SHM_NPAGES && region->sr_pages[i] != 0; i++)
{
mm_pgfree(region->sr_pages[i], 1);
}
/* Reset the region entry to its initial state */
nxmutex_destroy(&region->sr_lock);
memset(region, 0, sizeof(struct shm_region_s));
}