Re: getting fd from pointer to sock

[Chris Wright <chris@wirex.com>]

* Amit Shah (shahamit@gmx.net) wrote:
> Hi,
> 
> I wanted a mapping from the scok struct to the fd... I know the mapping from
> the task_struct to the sock... I just want the reverse.

You can't definitively do it.  You can get filp from
struct sock -> struct socket -> struct file

And the forward lookup path you can get filp from
fd -> struct task_struct -> struct files_struct -> struct file

You can compare the filp's and see which match.  However multiple fd's
can point to the same filp (as in dup(2)), so you are never guaranteed a
1:1 mapping.  At best you can tell which fd(s) -- note possibly plural --
are pointing to the socket (or file).

cheers,
-chris
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