On Wed, 2006-04-05 at 23:20 +0200, Vincenzo Mallozzi wrote:
> I've thinked solution like this (similar to the one
> taha has suggested):
>
> static ssize_t read(struct file *file, char __user
> *buf, size_t count,
> loff_t *pos){
> int element_size = sizeof(char)/ sizeof(pid_t) /*
> To get the
> array size for pids*/
> int char_array_size = count / element_size;
> char *char_array = (char*) pid_array;
>
> /* .... This is your array ... fill what ever you
> want to fill in
> */
> }
>
>
> but I've a doubt.
> the array i had to pass to the user space is a array
> of string, therefore of char pointers. So the solution
> i've wrote above is sufficient?
Man! is it an array of pid_t elements or array of char pointers.
If it is pointers! then things are complicated as you
have to pass the memory associated not the pointer to user space...
As far as I remember, earlier it was array of pid_t's....
taha
> thanks.
> Vincenzo MAllozzi
> --- taha hafeez <tawushafeez@xxxxxxxxx> ha scritto:
>
> > On Mon, 2006-04-03 at 00:26 +0200, Vincenzo Mallozzi
> > wrote:
> > > --- taha siddiqi <tawushafeez@xxxxxxxxx> wrote:
> > >
> > > > Hi
> > > >
> > > > Same answer, "please explain the situation !!"
> > > >
> > > > taha
> > > >
> > > > Thanks.
> > >
> > > The array I want to pass from kernel space to user
> > > space contains pid_t elements.
> > > First, I pass the length of the array from user
> > space
> > > to kernel space.
> > > Then, I build the array with the given length
> > filling
> > > it with the pid of processes I need to monitor.
> > > Finally, I've to pass this array of pids to the
> > user
> > > space.
> > > I hope I've well explained the situation.
> > > Thanks all.
> > > Vincenzo Mallozzi.
> > >
> >
> > Well, I think I get you now....
> >
> > Correct me if I am wrong...
> >
> >
> > data buffer
> > USER_SPACE ------------> KERNEL SPACE [fill data
> > with pid_t]
> > ^ |
> > | |
> > *------<----------------*
> > data buffer
> >
> > Why do we need to pass the data buffer to kernel ?
> > Does it contain any information that kernel needs ?
> > if not, then that step can be avoided ?
> >
> > Then you just need a read call implementation of
> > struct file_operations {}.
> >
> > taha
> >
> >
> >
> >
>
>
>
>
>
>
>
> ___________________________________
> Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB
> http://mail.yahoo.it
>
> --
> Kernelnewbies: Help each other learn about the Linux kernel.
> Archive: http://mail.nl.linux.org/kernelnewbies/
> FAQ: http://kernelnewbies.org/faq/
>
--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
