[CRIU] rewriting images via criu (or crit?)

[Pavel Emelyanov]

On 10/21/2014 04:58 PM, Tycho Andersen wrote:
> On Tue, Oct 21, 2014 at 01:22:06PM +0400, Cyrill Gorcunov wrote:
>> On Tue, Oct 21, 2014 at 12:13:06PM +0300, Ruslan Kuprieiev wrote:
>>>> As to me -- external tool for such modifications is better choise and it seems
>>>> crit is exactly fits here. This might have slight impact on the speed in compare
>>>> if the language would builtin into criu itself, but criu is already complex enough
>>>> so adding language engine here would simply overload I think.
>>>
>>> I totally agree with Cyrill.
>>>
>>> I like the syntax. Are you thinking about using crit like so:
>>> crit modify -i cgroup.img cgroup_entry.controllers["cpuset" in
>>> cnames]//properties[name="cpuset.cpus"] set value=0-1
>>> right?
>>
>> I guess so. Also I would consider introdusing more human-readable
>> syntax if possible, but that's optional, up to you and Tycho.
> 
> Suggestions are welcome; I just picked this because xpath is the only
> language I could think of that has similar goals, so it might be
> something that people were familiar with.

I like the idea of xpath language, it seems to be suitable for images.

BTW, In criu images we have a feature that differs them from xml -- we
have arrays of similar messages in many files, e.g. in reg-files. What
if we want to edit paths only on entries, that match some criteria,
e.g. we moved /home/foo into /home/bar and want to s#/home/foo#/home/bar#,
but leave all the other paths (e.g. /etc/*) intact. Will we be able to
construct the xpath expression to address that?


Nonetheless, Ruslan, can you (after finishing with basic crit stuff) find 
out whether there's standard python library for xpath and how fast/slow 
it is? :)

Thanks,
Pavel