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From: Xavier Leroy <xavier.leroy@inria.fr>
To: Matt Gushee <mgushee@havenrock.com>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Apparent I/O bug
Date: Sat, 31 Jan 2004 10:38:06 +0100	[thread overview]
Message-ID: <20040131103806.B17938@pauillac.inria.fr> (raw)
In-Reply-To: <20040131084640.GA12067@swordfish>; from mgushee@havenrock.com on Sat, Jan 31, 2004 at 01:46:40AM -0700

> I have encountered what appears to be a bug in out_channels created with
> Pervasives.open_out_gen:
> 
>   bash-2.05a$ ocaml
>           Objective Caml version 3.07+2
>   
>   # let oc = open_out_gen [Open_creat; Open_text] 0o644 "/var/tmp/foo";;
>   val oc : out_channel = <abstr>
>   # output_string oc "Fubar Baz\n";;
>   - : unit = ()
>   # close_out oc;;
>   Exception: Sys_error "Bad file descriptor".
> 
> Well, that's disturbing. Or is there something I don't understand about
> the proper usage of open_out_gen (documentation problem?)?

In your call to open_out_gen, you didn't request write permission
(the list of flags doesn't contain "Open_wronly").  So, attempts to
write to the underlying file descriptor will fail.  Since out_channels
are buffered, the error isn't reported at the first output_string, but
only when an actual OS write takes place, i.e. at close_out in your example.

> BTW, I'm running OCaml on Debian GNU/Linux 3.0 (Woody), with glibc
> 2.2.5. I installed OCaml 3.07pl2 from source, with no apparent
> compilation errors. I am seeing the same problem on two similarly
> configured systems.

It is standard POSIX behavior.

- Xavier Leroy

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  reply	other threads:[~2004-01-31  9:38 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-01-31  8:46 Matt Gushee
2004-01-31  9:38 ` Xavier Leroy [this message]
2004-01-31  9:53   ` Matt Gushee

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