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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada x <whatever> Datagram Sockets
Date: Thu, 7 Feb 2019 19:00:03 +0100
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Xref: reader01.eternal-september.org comp.lang.ada:55460
Date: 2019-02-07T19:00:03+01:00
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On 2/7/19 12:47 PM, Jere wrote:
> 
> In Ada you are telling it to receive:
> 
> <length byte 1..4> <data byte 1..length>

Wrong. According to ARM 13.13.2(26/3) says, "If T is an array type, S'Output 
first writes the bounds, and S'Input first reads the bounds." Ada arrays do not 
necessarily have a lower bound of 1.

So String'Input will first try to read 2 integers, the lower and upper bounds of 
the array. Presumably it runs out of data while reading the 2nd, leading to the 
exception.

What the OP needs to do is

1. Get Length, the length of the data.
2. Create C : Interfaces.C.char_array (1 .. Length)
3. Transfer the data into C
4. Use Interfaces.C.To_Ada (C) to transform C into an Ada String

-- 
Jeff Carter
"Now go away or I shall taunt you a second time."
Monty Python & the Holy Grail
07