Re: [Patch] gutenprint53+usb crashes with libusb-1.0.25

On 2/23/22 10:25, Benjamin Berg wrote:
> Hi,
>
> On Wed, 2022-02-23 at 09:34 +0100, Zdenek Dohnal wrote:
>> thank you for looking into the issue!
>>
>> On 2/22/22 19:00, Solomon Peachy wrote:
>>> On Tue, Feb 22, 2022 at 07:55:18AM +0100, Zdenek Dohnal wrote:
>>>> there were changes in libusb 1.0.25 which is in Fedora 36 - f.e. default USB
>>>> context is not initialized unless you specifically pass NULL into
>>>> `libusb_init()` - gutenprint53+usb backend actually depended on this hidden
>>>> behavior, because it passes its own context address into `libusb_init()`
>>>> instead of NULL. So the change causes the backend to crash if you run it:
>>> Yikes!
>>>
>>>> According libusb maintainer, Ben Berg, the backend can work with the default
>>>> USB context and he prepared the patch for it (the file is attached). I was
>>>> able to verify the patch fixes the crash, but I don't have a device
>>>> supported by gutenprint itself, so I couldn't do an additional sanity
>>>> testing. The patch looks good to me though.
>>> Will this work for multi-threaded stuff where there could conceivably be
>>> multiple contexts in use?  That's not being exercised in the current
>>> gutenprint code but some of the stuff I have cooking will change that.
>> Ben, would you mind looking into it? IMO we probably cannot use a
>> default USB context for multi-threading...
>>
>> In such case, IMO we can init the default context just for the
>> print_help() scope and close it after we're done with it.
>>
>> You can join us in discussion on the bug if you are able as well [1],
>> I've pinged Robert there as well, because I didn't know your email for
>> bugzilla...
> I am already subscribed to that bug. :)
I'm sorry for mystification... (that's what I got for adding text into 
email at last minute and don't read it as whole at the end) - I meant 
Solomon in the last paragraph :)
>
-- 
Zdenek Dohnal
Software Engineer
Red Hat, BRQ-TPBC