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Message-ID: <728201270601301232v6da6fc2el7148ec33896d6b97@mail.gmail.com>
Date: Mon, 30 Jan 2006 20:32:33 +0000
From: Ram Gupta <ram.gupta5@gmail.com>
To: Bernard Blackham <bernard@blackham.com.au>
Subject: Re: Unique /proc/<pid>/fd/ inode numbers?
Cc: linux-kernel@vger.kernel.org
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On 1/30/06, Bernard Blackham <bernard@blackham.com.au> wrote:
> A useful thing to be able to determine when checkpointing a process
> from userspace is whether two file descriptors that point to the
> same file are
>    (a) two independently open()'d instances of the file; or
>    (b) one open() and one dup().
> (the latter case meaning the FDs share locks & seek offsets).
>

I dont see a way  which differentiates between open fd & dup fd. The
only  difference between them is that when doing open it allocates a
new file structure & initializes it while in case of dup the same file
pointer. That's how you share the locks & seek offsets. But I dont see
any kernel code which makes this difference currently. Implementing
this should not be that hard any way

regards
Ram Gupta
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