On Mon, Dec 14, 2009 at 11:28, Johannes Stezenbach <js@xxxxxxxxx> wrote:
> On Mon, Dec 14, 2009 at 10:14:50AM +0100, Martin Pitt wrote:
>>
>> A gotcha that I see here is that the force_release only ever gets
>> appended to. I. e. whenever we run udevtrigger, we'd append the same
>> keys again. POSIX shell doesn't have elaborate substring matching
>> capabilities like bash's ${x/pattern/string}, so it might not be too
>> easy to check if we already have a key in POSIX sh. (But please don't
>> call grep in a loop; let's rather rewrite this bit in C). There might
>> be some trickery with splitting by IFS=, into an array or so, if you
>> want to keep using sh?
>
> The problem is that force_release is preset by the kernel, so
> in order to do what you want we need either
> a) pass both old and new key list on "change"
> b) save initial force_release value to a file on "add"
> and use the file on "change"
It should just not mangle the sysfs string if the value is already
contained. Why would you need to store anything between a "change" and
"add" event? Both events are handled the same way, and the two
independent events run one after each other.
I guess the logic to append a value to the sysfs string only if needed
should be done in a tine C program, or a sed script with a RUN+= call
directly to sed maybe can be used ...
Thanks,
Kay
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