Re: [PATCH] install.sh: Preserve directory symlinks

["Thierry Escande" <thierry.escande@xxxxxxxxxx>]

On 3/19/26 15:09, Jan Beulich wrote:
> On 19.03.2026 14:59, Thierry Escande wrote:
>> On 3/19/26 14:48, Jan Beulich wrote:
>>> On 19.03.2026 14:26, Thierry Escande wrote:
>>>> On 3/19/26 10:31, Jan Beulich wrote:
>>>>> On 13.03.2026 18:25, Thierry Escande wrote:
>>>>>> In various distros (i.e. Debian) some folders like /lib or /var/run are
>>>>>> symlinks. Using the tar option --keep-directory-symlink preserves these
>>>>>> symlinks.
>>>>>>
>>>>>> Signed-off-by: Thierry Escande <thierry.escande@xxxxxxxxxx>
>>>>>> ---
>>>>>>  install.sh | 2 +-
>>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/install.sh b/install.sh
>>>>>> index 3e11c4d46f..5d0b7a4933 100644
>>>>>> --- a/install.sh
>>>>>> +++ b/install.sh
>>>>>> @@ -27,7 +27,7 @@ tmp="`mktemp -d`"
>>>>>>  echo "Installing Xen from '$src' to '$dst'..."
>>>>>>  (cd $src; tar -cf - * ) | tar -C "$tmp" -xf -
>>>>>>  
>>>>>> -(cd $tmp; tar -cf - *) | tar --no-same-owner -C "$dst" -xf -
>>>>>> +(cd $tmp; tar -cf - *) | tar --no-same-owner -C "$dst" 
>>>>>> --keep-directory-symlink -xf -
>>>>>
>>>>> How compatible (between flavors of tar as well as between versions of GNU
>>>>> tar) is use of this option?
>>>>
>>>> It's supported by GNU tar since version 1.27 (from ~12 years ago) but it
>>>> seems to be the only implementation that supports it. BSD and busybox
>>>> don't support it. I didn't check for other implementations.
>>>>
>>>> I can add a flavor/version check if that makes sense.
>>>
>>> Possibly. One question then is what the behavior was prior to that option
>>> having been introduced.
>>
>> From the patch at [1] introducing the option, and more precisely the
>> test done at [2], directory symlinks were simply overwritten.
> 
> Which makes it hard to suggest useful behavior when the option is unavailable:
> Simply refusing to install isn't nice, but corrupting the installation is
> perhaps even worse.
> 
> I take it that the (presumably) more standard -h doesn't help here?

-h definitely helps but it has the same behavior for files and folders.
So if an already existing symlink is meant to be replaced by a file,
then it won't. I chose to use the folder specific option.

That being said there is probably no usecase where a real file replaces
a symlink in the dist archive. And anyway, that would also stand for
folders.

I'll send a v2 with -h.

Regards,



--
Thierry Escande | Vates XCP-ng Developer

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