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From: dennison@telepath.com
Subject: Re: Interfaces.C.Strings_Chars_Ptr as an out mode parameter
Date: 1999/06/11
Message-ID: <7jr9s1$ij8$1@nnrp1.deja.com>#1/1
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References: <7jpe2e$m7i@hobbes.crc.com>
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Date: 1999-06-11T00:00:00+00:00
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In article <7jpe2e$m7i@hobbes.crc.com>,
  "David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> wrote:
> procedure My_Proc (Result : out Interfaces.C.Strings.Chars_Ptr);
>
> is it legal to export it like so:
>
> pragma Export (C, My_Proc, "My_Proc");
>
> where the C prototype is void My_Proc (char * result);
>
> The results I'm having are that if the exported procedure
> is called from Ada, everything works as expected.
>
> If called from C, a Segmentation fault occurs at the
> point where the out mode parameter is assigned its
> value in the Ada procedure My_Proc.

If the implementation advice in the RM is followed, then your Ada
"myproc" is equivalent to a C "My_Proc (char ** result)". To get the
equivalent of a C "My_Proc (char * result)" you should either change
your mode to "in" or change your type to "Interfaces.C.Signed_Char"


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