cbuf.c
2.66 KB
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/**
* \file
*
* \author Georg Hopp
*
* \copyright
* Copyright © 2012 Georg Hopp
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define _POSIX_SOURCE
#define _POSIX_C_SOURCE 200112L
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include "trbase.h"
#include "tr/cbuf.h"
static void cbufDtor(void*);
static
int
cbufCtor(void * _this, va_list * params)
{
TR_Cbuf this = _this;
char state = -1;
char * shm_name = va_arg(*params, char*);
long psize = sysconf(_SC_PAGESIZE);
size_t size;
int shm;
char * data;
this->shm_name = TR_malloc(strlen(shm_name) + 7 + 2);
sprintf(this->shm_name, "/%06d_%s", getpid(), shm_name);
/**
* align size at page boundary.
* increase as neccessary
*/
size = va_arg(*params, size_t);
size = (0 >= size)? 1 : (0 != size%psize)? (size/psize)+1 : size/psize;
this->bsize = psize * size;
while (-1 == state) {
shm = shm_open(this->shm_name, O_RDWR|O_CREAT|O_EXCL, S_IRWXU);
if (-1 == shm) {
break;
}
if (-1 == ftruncate(shm, this->bsize)) {
break;
}
this->data = mmap (0, this->bsize << 1,
PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
if (this->data == MAP_FAILED) {
this->data = NULL;
break;
}
data = mmap (this->data, this->bsize,
PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, shm, 0);
if (data != this->data) {
break;
}
data = mmap (this->data + this->bsize, this->bsize,
PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, shm, 0);
if (data != this->data + this->bsize) {
break;
}
state = 0;
}
if (-1 != shm) {
shm_unlink(this->shm_name);
close(shm);
}
return state;
}
static
void
cbufDtor(void * _this)
{
TR_Cbuf this = _this;
TR_MEM_FREE(this->shm_name);
if (NULL != this->data && MAP_FAILED != this->data) {
munmap(this->data, this->bsize << 1);
}
this->data = NULL;
}
TR_INIT_IFACE(TR_Class, cbufCtor, cbufDtor, NULL);
TR_CREATE_CLASS(TR_Cbuf, NULL, TR_IF(TR_Class));
// vim: set ts=4 sw=4: