Function sys_dup2

components/dfs/dfs_v2/src/dfs.c:845–902

* @brief System call to duplicate a file descriptor to a specific descriptor number * * @param[in] oldfd The file descriptor to duplicate * @param[in] newfd The desired file descriptor number * * @return rt_err_t The new file descriptor number if successful (>=0), * -RT_ENOSYS if filesystem lock failed, * -1 if operation failed (invalid descriptors or allocation failed) */

 *         -1 if operation failed (invalid descriptors or allocation failed)
 */
rt_err_t sys_dup2(int oldfd, int newfd)
{
    struct dfs_fdtable *fdt = NULL;
    int ret = 0;
    int retfd = -1;

    if (dfs_file_lock() != RT_EOK)
    {
        return -RT_ENOSYS;
    }

    /* check old fd */
    fdt = dfs_fdtable_get();
    if ((oldfd < 0) || (oldfd >= fdt->maxfd))
    {
        goto exit;
    }
    if (!fdt->fds[oldfd])
    {
        goto exit;
    }
    if (newfd < 0)
    {
        goto exit;
    }
    if (newfd >= fdt->maxfd)
    {
        newfd = _fdt_slot_expand(fdt, newfd);
        if (newfd < 0)
        {
            goto exit;
        }
    }
    if (fdt->fds[newfd] == fdt->fds[oldfd])
    {
        /* ok, return newfd */
        retfd = newfd;
        goto exit;
    }

    if (fdt->fds[newfd])
    {
        ret = dfs_file_close(fdt->fds[newfd]);
        if (ret < 0)
        {
            goto exit;
        }
        fd_release(newfd);
    }

    fdt->fds[newfd] = fdt->fds[oldfd];
    /* inc ref_count */
    rt_atomic_add(&(fdt->fds[newfd]->ref_count), 1);
    retfd = newfd;
exit:
    dfs_file_unlock();
    return retfd;
}