src/cbuf/cbuf.c

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#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 "class.h"
#include "utils/memory.h"

#include "cbuf.h"


static void cbufDtor(void*);

static
int
cbufCtor(void * _this, va_list * params)
{
        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 = malloc(strlen(shm_name) + 7 + 2);
        sprintf(this->shm_name, "/%06d_%s", getpid(), shm_name);

        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)
{
        Cbuf this = _this;

        FREE(this->shm_name);

        if (NULL != this->data && MAP_FAILED != this->data) {
                munmap(this->data, this->bsize << 1);
        }

        this->data = NULL;
}

INIT_IFACE(Class, cbufCtor, cbufDtor, NULL);
CREATE_CLASS(Cbuf, NULL, IFACE(Class));

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