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From: xorquewasp@googlemail.com
Newsgroups: comp.lang.ada
Subject: Converting pointers to non nul-terminated C "strings" to Ada string
Date: Fri, 13 Feb 2009 22:58:55 -0800 (PST)
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Date: 2009-02-13T22:58:55-08:00
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Hello.

I have some C code that returns a pointer to a buffer of
"data" (not a string, just raw data) and also returns the
size of the buffer:

void
get_data (char **ptr, int *size);

int size;
char *ptr;

get_data (&ptr, &size);

The code is part of a library that I don't control, so I can't
change the interface.

I've defined the Ada equivalent as:

    package CS renames Interfaces.C.Strings;
    package C renames Interfaces.C;

    procedure memory_data
      (data   : out CS.chars_ptr;
       size   : out C.int);
    pragma Import (C, memory_data, "get_data");

This works correctly, however I'm having trouble converting
the chars_ptr type to an Ada string given that it's not nul-
terminated.

Attempts to do the following:

return CS.Value (Item => data, Length => size);

... results in a String as long as the position of the first nul in
the
C string (the position is inevitably less than the length of the
string).

Is it possible to properly convert unterminated C strings or do I
need to start messing about with raw System.Address types?