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/****************************************************************************
* Copyright (C) 2009-2015 EPAM Systems
*
* This file is part of Indigo toolkit.
*
* This file may be distributed and/or modified under the terms of the
* GNU General Public License version 3 as published by the Free Software
* Foundation and appearing in the file LICENSE.GPL included in the
* packaging of this file.
*
* This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
* WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
***************************************************************************/
#if !defined(_WIN32)
#include <string.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include "base_cpp/shmem.h"
using namespace indigo;
IMPL_ERROR(SharedMemory, "shared memory");
SharedMemory::SharedMemory (const char *name, int size, bool no_map_if_first)
{
snprintf(_filename, sizeof(_filename), "/tmp/indigo_shm_%s", name);
_pointer = NULL;
_was_first = false;
int key = ftok(_filename, 'D'); // 'D' has no actual meaning
if (key == -1 && errno == ENOENT)
{
// create file
int fd = creat(_filename, 0666);
if (fd == -1)
throw Error("can't create %s: %s", _filename, strerror(errno));
key = ftok(_filename, 'D');
}
if (key == -1)
throw Error("can't get key: %s", strerror(errno));
_shm_id = -1;
if (!no_map_if_first)
{
// try to create
_shm_id = shmget(key, size, IPC_CREAT | IPC_EXCL | 0666);
if (_shm_id == -1)
{
if (errno != EEXIST)
throw Error("can't shmget: %s", strerror(errno));
}
else
_was_first = true;
}
if (_shm_id == -1)
{
_shm_id = shmget(key, size, 0666);
if (_shm_id == -1)
{
if (errno == ENOENT)
return;
throw Error("can't second shmget (%d): %s", key, strerror(errno));
}
}
_pointer = shmat(_shm_id, NULL, 0);
if (_pointer == (void *)-1)
throw Error("can't shmat: %s", strerror(errno));
strncpy(_id, name, sizeof(_id));
if (_was_first)
memset(_pointer, 0, size);
}
SharedMemory::~SharedMemory ()
{
struct shmid_ds ds;
// detach from the memory segment
if (shmdt((char *)_pointer) != 0)
return; // throwing exceptions on destructor is bad
// get information about the segment
if (shmctl(_shm_id, IPC_STAT, &ds) != 0)
return;
if (ds.shm_nattch < 1)
{
// nobody is using the segment; remove it
shmctl(_shm_id, IPC_RMID, NULL);
// and remove the temporary file
unlink(_filename);
}
}
#endif
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