Re: [PATCH v12 0/4] MR6855: server: Fix renaming file to a hardlink of itself.

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about server/fd.c:
> - if (!strcmp( srcname, dstname )) goto ret;
> -
> - /* This is more complicated now, because in case of a casefold (+F) directory, the destination may very well be the same dentry,
> -
> * even if the name doesn't match (if it differs just by case), in which case unlinking it is wrong and can be dangerous. Instead,
> -
> * we first rename the source to a temporary filename in the same directory. If this is a casefold dir, this will also remove the
> -
> * destination, otherwise the destination still exists. We then create a hardlink from the destination to our temporary name, and
> -
> * finally, unlink the temporary. This still works if the directory is case sensitive, so it's not a problem in either case. */
> - tmp_value += (current_time >> 16) + current_time;
> - for (i = 0; i < 0x8000; i++, tmp_value += 7777)
> - {
> -
>    snprintf( tmpname, sizeof(tmpname), tmpname_fmt, tmp_value );
> -
> -
>    /* create an empty file or directory to avoid TOCTTOU */
> -
>    if (!is_dir)
> -
>    {
> -
>        int fd = openat( dirfd, tmpname, O_CREAT | O_EXCL, 0777 );

```suggestion:-0+0
            int fd = openat( dirfd, tmpname, O_CREAT | O_EXCL | O_WRONLY, 0666 );
```

For consistency with server/registry.c. It's a good idea to stick to the most typical combination of parameters for filesystem operations, to reduce conflict with ACL or LSM.