Re: [PATCH 4/4 v2] dpkg-base: Update git alternates

[Alexander Smirnov <asmirnov@ilbers.de>]

On 11/27/2017 10:44 AM, Henning Schild wrote:
> Am Fri, 24 Nov 2017 18:12:43 +0300
> schrieb Alexander Smirnov <asmirnov@ilbers.de>:
> 
>> On 11/24/2017 05:57 PM, Henning Schild wrote:
>>> Am Thu, 23 Nov 2017 13:25:32 +0300
>>> schrieb Alexander Smirnov <asmirnov@ilbers.de>:
>>>    
>>>> Update git alternates to work in buildchroot.
>>>>
>>>> Signed-off-by: Alexander Smirnov <asmirnov@ilbers.de>
>>>> ---
>>>>    meta/classes/dpkg-base.bbclass | 7 +++++++
>>>>    1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/meta/classes/dpkg-base.bbclass
>>>> b/meta/classes/dpkg-base.bbclass index 21ae88d..d51a709 100644
>>>> --- a/meta/classes/dpkg-base.bbclass
>>>> +++ b/meta/classes/dpkg-base.bbclass
>>>> @@ -18,6 +18,13 @@ dpkg_runbuild() {
>>>>    
>>>>    # Wrap the function dpkg_runbuild with the bind mount for
>>>> buildroot do_build() {
>>>> +    if [ -d ${WORKDIR}/git/.git ]; then
>>>> +        OBJ_PATH=$(cat
>>>> ${WORKDIR}/git/.git/objects/info/alternates)
>>>> +        REPO_PATH=$(dirname $OBJ_PATH)
>>>> +        REPO_NAME=$(basename $REPO_PATH)
>>>> +        echo "/git/$REPO_NAME/objects" >
>>>> ${WORKDIR}/git/.git/objects/info/alternates
>>>> +    fi
>>>
>>> Does that not overwrite a file so that the repo can now work only in
>>> buildchroot and will be broken on the host?
>>>    
>>
>> It does, but in general there is no use-case for having working repo
>> clone on the host. I could restore original alternates in cleanup
>> hook, but it really makes no sense.
> 
> I do not like breaking that clone, even for a short while and repairing
> it later.
> The host-clone might be looked at while debugging.
> And one could imagine the fetcher/unpacker supporting deduplication if
> multiple recipes use the same repo. Even if such a feature is not
> present in bitbake today, if it is implemented Isar will break. Think
> one recipe being in do_build and another one in do_fetch at the same
> time.

Don't understand what you mean, but probably the following items could 
better describe what happens in this patch:

1. There is Isar downloads folder 'tmp/downloads', which contains git 
clones from origins.
2. There is workdir folder per recipe, which contains git clone from 
Isar downloads folder.
3. The patch modifies clone in workdir, so the only current recipe is 
user for this repo.
4. The downloads folder content stays unmodified for all the time.

Alex