[sane-devel] Has anyone managed to get Snapscan backend working with FreeBSD 8.0 (which uses libusb)?

[m. allan noah]

On Thu, Jan 28, 2010 at 6:51 AM, Oliver Schwartz <Oliver.Schwartz at gmx.de> wrote:
> Hi all,
>
> On 26.01.2010, at 15:46, m. allan noah wrote:
>
>> Seems like an individual backend should not need to parse the device
>> string. Isn't there some other way to come up with a unique semaphore,
>> like process id?
>
>
> the process id could be used, but it may fail theoretically. One example is
> a frontend that uses two (snapscan-)scanners at the same time (not that I
> think anybody actually does that).
>
> The clean solution is a semaphore per device. In the days before libusb the
> backend used ftok(). The current code was written by Julien, as far as I
> know, because the ftok() call failed miserably and the unique id was always
> 0.
>
> So I guess I'll stay with the device string, but maybe use some sort of crc
> instead of parsing it. Other ideas are, of course, welcome.

I would do both- process ID combined with a hash of the device name,
unless you have the ability to get a unique serial number out of the
hardware...

allan
-- 
"The truth is an offense, but not a sin"