On Wednesday, April 16, 2014 8:57 AM, Ian Abbott wrote: > On 2014-04-15 18:37, H Hartley Sweeten wrote: >> The only time the chanlist can be NULL and chanlist_len < 1 is when a >> COMEDI_CMDTEST ioctl is done, usually for the comedilib function >> comedi_get_cmd_src_mask(). This comedilib function sets all the command >> sources to TRIG_ANY and Step 1 of the (*do_cmdtest) will fail returning >> a the mask of valid sources. >> >> For the rest of the (*do_cmdtest) and the (*do_cmd) functions a valid >> chanlist and chanlist_len >= 1 is required. >> >> Modify the check in __comedi_get_user_chanlist() to allow a NULL >> chanlist or chanlist_len < 1 only when all the command sources are >> TRIG_ANY. >> >> Remove the checks in the comedi_driver (*do_cmdtest) functions that >> don't result in to much diff noise. The remaining ones will be removed >> in following patches. >> >> Signed-off-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx> >> Cc: Ian Abbott <abbotti@xxxxxxxxx> >> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > NAK. This will break existing libcomedi library function > comedi_get_generic_timed(), which will call the COMEDI_CMDTEST ioctl > with a NULL chanlist (but with chanlist_len > 1) and with start_src etc. > set to values other than TRIG_ANY. > > For COMEDI_CMDTEST, chanlist is allowed to be NULL and chanlist_len is > allowed to be 0 (although some drivers' do_cmdtest handlers currently > check it is at least 1). (However, the command structure might get > modified in strange ways if the command test gets as far as "step 3" > with a zero chanlist_len, so it's best for the user-level code to set a > proper chanlist_len if it's expecting the test to get as far as "step 3".) > > However, for the COMEDI_CMD ioctl, chanlist_len needs to be at least 1 > and chanlist needs to be non-NULL, but its NULL-ness shouldn't be > checked until after s->do_cmdtest() has been called, as that can modify > the erroneous command before passing it back to the user. Grrr... Missed that part in the comedilib __generic_timed() function. Probably best to drop this series for now and I'll dig back into it. Thanks, Hartley _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
