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From: vlc <just.another.spam.account@googlemail.com>
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Subject: Re: Atomic file creation
Date: Mon, 4 Jan 2010 06:45:41 -0800 (PST)
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Date: 2010-01-04T06:45:41-08:00
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On Jan 4, 3:25=A0pm, Georg Bauhaus <rm.dash-bauh...@futureapps.de>
wrote:
> A multitasking program can use a protected object
> for this. =A0Have all tasks perform I/O if and only if
> it is their turn as decided by the queuing control of
> the protected object.

The problem is that this file can also be created by other processes,
neither written by me nor in Ada. I doubt that I can convince an
application that I only have as a binary to respect something like
Ada's protected objects ...

> Strictly speaking, O_EXCL is not C, but it is provided by Unix's
> open(2) call. fopen(3), which is C, does not offer exclusive access
> IIRC.

That's right. I slowly mix up C with Unix.

> The Form string parameter of your Ada implementation might
> provide sharing control. =A0The docs will then explain how a
> Form value affects files opened by many tasks; possibly even
> explain whether the form strings have an effect on using the
> external file in other programs.

Gnat only supports the SHARED and WCEM form strings, and if I
understand the documentation correctly, they have nothing to do with
exclusive open.

Thanks a lot!