io functions

int iom_init (size_t len, const char *path, io_map_t *proc)
{
    size_t filesize;

    (proc)->pos = 0;

    (proc)->fd = open(path, O_RDWR|O_CREAT);

    if ((proc)->fd < 0)
        goto out;

    filesize = lseek((proc)->fd, 0, SEEK_END);

    if (!filesize && len != LEN_FILESIZ) {
        lseek((proc)->fd, len-1, SEEK_SET);
        write((proc)->fd, "", 1);
    } else if (filesize && len == LEN_FILESIZ) {
        len = filesize;
    } else {
        errno = EINVAL;
        goto cl_sock;
    }

    (proc)->len = len;

    (proc)->map_mem = mmap(0, len, PROT_ALL, MAP_SHARED, (proc)->fd, 0);

    if ((proc)->map_mem == MAP_FAILED)
        goto cl_sock;

    return 0;

cl_sock:
    close((proc)->fd);
    (proc) = NULL;
out:
    return 1;
}

int iom_w32(unsigned int val, int endian, io_map_t *proc)
{
    if ((proc)->pos >= ((proc)->len - 4))
        return ENOBUFS;

    if (endian == ENDIAN_BIG) {
        (proc)->map_mem[(proc)->pos++] = val & 0xFF;
        (proc)->map_mem[(proc)->pos++] = (val >> 8) & 0xFF;
        (proc)->map_mem[(proc)->pos++] = (val >> 16) & 0xFF;
        (proc)->map_mem[(proc)->pos++] = (val >> 24) & 0xFF;
    } else if (endian == ENDIAN_LITTLE) {
        (proc)->map_mem[(proc)->pos++] = (val >> 24) & 0xFF;
        (proc)->map_mem[(proc)->pos++] = (val >> 16) & 0xFF;
        (proc)->map_mem[(proc)->pos++] = (val >> 8) & 0xFF;
        (proc)->map_mem[(proc)->pos++] = val & 0xFF;
    } else {
        return EINVAL;
    }

    return 0;
}