Re: read() called twice for /proc files

[Jonathan Lundell <jlundell@pobox.com>]

At 6:34 PM -0700 2001-09-24, Tim Hockin wrote:
>Is there a general solution to the case of read() being called minimum
>twice for a file in /proc?  I have a small file in /proc, whose data takes
>a fair time to generate.  My read() handler gets called once for the data,
>and once so I can return 0 to terminate read().

I'm guessing you mean that the user is calling read once (and not a 
second time to get the 0/eof return), and that proc_file_read() is 
calling your read_proc twice. If that's the case, you can just set 
the eof flag on the first call (on which you return the data), and 
you won't be called again unless the user reads again.

And of course, as David Miller suggests, you can check the offset 
first, before generating data.
-- 
/Jonathan Lundell.