[ale] Programming /proc

[Bao C. Ha]

Just returns an empty string in *buffer and set len to zero.
It will tell the reader, which is most likely a blocked read,
that there is nothing left.

Bao

> -----Original Message-----
> From: Benjamin Dixon [mailto:beatle at arches.uga.edu]
> Sent: Thursday, November 15, 2001 10:11 AM
> To: Bao C. Ha
> Cc: ale at ale.org
> Subject: RE: [ale] Programming /proc
> 
> 
> 
> Yeah I finally found it last night with a little grep action. 
> Thanks for
> the reply though. Anyway, I've got my module printing out the data I
> wanted but I don't know how to specify EOF under the new system! So it
> prints the data forever. In the old system you could set the 
> eof pointer
> passed in to the function to 1 and it would work (if I 
> remember right) but
> I don't see how to do that in this scenario since there is no 
> eof pointer
> being passed in.
> 
> Ben
> 
> On Thu, 15 Nov 2001, Bao C. Ha wrote:
> 
> > 
> > Since /proc is a pseudo-filesystem, I look for it in
> > <linux/fs.h>.
> > 
> > struct file {
> >         struct list_head        f_list;
> >         struct dentry           *f_dentry;
> >         struct vfsmount         *f_vfsmnt;
> >         struct file_operations  *f_op;
> >         atomic_t                f_count;
> >         unsigned int            f_flags;
> >         mode_t                  f_mode;
> >         loff_t                  f_pos;
> >         unsigned long           f_reada, f_ramax, f_raend, 
> f_ralen, f_rawin;
> >         struct fown_struct      f_owner;
> >         unsigned int            f_uid, f_gid;
> >         int                     f_error;
> > 
> >         unsigned long           f_version;
> > 
> >         /* needed for tty driver, and maybe others */
> >         void                    *private_data;
> > 
> >         /* preallocated helper kiobuf to speedup O_DIRECT */
> >         struct kiobuf           *f_iobuf;
> >         long                    f_iobuf_lock;
> > };
> > 
> > Bao
> > 
> > > -----Original Message-----
> > > From: Benjamin Dixon [mailto:beatle at arches.uga.edu]
> > > Sent: Wednesday, November 14, 2001 10:58 PM
> > > To: ale at ale.org
> > > Subject: [ale] Programming /proc
> > >
> > >
> > >
> > > Hi all,
> > >
> > > I'm trying to write a kernel module that has proc support 
> but I don't
> > > fully understand the new calling procedures under 2.4. I have
> > > successfully
> > > set up my module code (easy enough) and now I want to let the
> > > user access
> > > some information using my output function which I register
> > > for "read" in a
> > > file_operations structure. So my function prototype looks 
> like this:
> > >
> > > static ssize_t output(struct file *file, char *buffer, size_t len,
> > >                       loff_t *offset);
> > >
> > > My only problem is, I'm not entirely sure how to handle the
> > > *file. Does
> > > anyone know where that structure is defined? I've 
> searched through the
> > > kernel, specifically includes, but can't find it. And more
> > > generally, does
> > > anyone know of a good resource for *2.4 kernel* /proc
> > > programming, its a
> > > bit different from 2.2 and previous kernels and I can't find
> > > any updated
> > > information. (BTW, I did find a procfs_example.c file in the
> > > Documentation
> > > directory but it doesn't tell me what I want to know, which
> > > is what those
> > > structures look like).
> > >
> > > Ben
> > >
> > >
> > > ---
> > > This message has been sent through the ALE general 
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> > > sent to listmaster at ale dot org.
> > >
> > 
> 
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