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To: caml-list@inria.fr
From: cashin@cs.uga.edu
Subject: Re: [Caml-list] Unix.lseek versus Pervasives.pos
Date: Wed, 19 Mar 2003 14:01:31 -0500
In-Reply-To: <20030319184840.GA12900@clipper.ens.fr> (Nicolas George's
 message of "Wed, 19 Mar 2003 19:48:40 +0100")
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Nicolas George <nicolas.george@ens.fr> writes:

...
> So you can see that the lseek is done before the read. And indeed, your
> calls to read and lseek can occur in an unspecified order. I guess that
> if you write
>
>   let len = UnixLabels.read ... in
>   let pos = UnixLabels.lseek ... in
>   Printf.printf ...
>
> you will get the right result.

You're right!

  ecashin@meili seek-tell$ ./test 
  after reading 10 chars: "let main =", position is 10
  ecashin@meili seek-tell$ cat main.ml
  let main = 
    let fd = Unix.openfile "main.ml" [Unix.O_RDONLY] 0 
    and buf = String.create 1024 in
    let n = UnixLabels.read fd ~buf ~pos:0 ~len:10 in
    Printf.printf "after reading %d chars: \"%s\", position is %d\n"
      n
      buf
      (UnixLabels.lseek fd 0 ~mode:Unix.SEEK_CUR)
  ;;
  
  main


-- 
--Ed L Cashin            |   PGP public key:
  ecashin@uga.edu        |   http://noserose.net/e/pgp/

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