dfs_rename should work when the new file exsits

[grissiom]

http://linux.die.net/man/3/rename

If the link named by the new argument exists, it shall be removed and old renamed to new. In this case, a link named new shall remain visible to other processes throughout the renaming operation and refer either to the file referred to by new or old before the operation began.

But in current dfs_rename, it will return -17, i.e., EEXIST. The link above said rename could return EEXIST, but in a different situation:

EEXIST or ENOTEMPTY
The link named by new is a directory that is not an empty directory.

This bug makes rename unusable in most of the scenarios.

[grissiom]

ping

[BernardXiong]

@prife please provide your comments.

[prife]

sorry for responding so late.

int dfs_file_rename(const char *oldpath, const char *newpath)
{
    int result;
    struct dfs_filesystem *oldfs, *newfs;
    char *oldfullpath, *newfullpath;

    result = DFS_STATUS_OK;
    newfullpath = RT_NULL;
    oldfullpath = RT_NULL;

    oldfullpath = dfs_normalize_path(RT_NULL, oldpath);
    if (oldfullpath == RT_NULL)
    {
        result = -DFS_STATUS_ENOENT;
        goto __exit;
    }

    newfullpath = dfs_normalize_path(RT_NULL, newpath);
    if (newfullpath == RT_NULL)
    {
        result = -DFS_STATUS_ENOENT;
        goto __exit;
    }

    oldfs = dfs_filesystem_lookup(oldfullpath);
    newfs = dfs_filesystem_lookup(newfullpath);

    if (oldfs == newfs)
    {
        if (oldfs->ops->rename == RT_NULL)
        {
            result = -DFS_STATUS_ENOSYS;
        }
        else
        {
            if (oldfs->ops->flags & DFS_FS_FLAG_FULLPATH)
                result = oldfs->ops->rename(oldfs, oldfullpath, newfullpath);
            else
                /* use sub directory to rename in file system */
                result = oldfs->ops->rename(oldfs,
                                            dfs_subdir(oldfs->path, oldfullpath),
                                            dfs_subdir(newfs->path, newfullpath));
        }
    }
    else
    {
        result = -DFS_STATUS_EXDEV;
    }

__exit:
    rt_free(oldfullpath);
    rt_free(newfullpath);

    /* not at same file system, return EXDEV */
    return result;
}

what rename in RTT return seems depends the rename implemented on the specific fs.