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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- I N T E R F A C E S . C . S T R I N G S --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2011, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with System; use System;
with System.Storage_Elements; use System.Storage_Elements;
with Ada.Unchecked_Conversion;
package body Interfaces.C.Strings is
-- Note that the type chars_ptr has a pragma No_Strict_Aliasing in the
-- spec, to prevent any assumptions about aliasing for values of this type,
-- since arbitrary addresses can be converted, and it is quite likely that
-- this type will in fact be used for aliasing values of other types.
function To_chars_ptr is
new Ada.Unchecked_Conversion (System.Parameters.C_Address, chars_ptr);
function To_Address is
new Ada.Unchecked_Conversion (chars_ptr, System.Parameters.C_Address);
-----------------------
-- Local Subprograms --
-----------------------
function Peek (From : chars_ptr) return char;
pragma Inline (Peek);
-- Given a chars_ptr value, obtain referenced character
procedure Poke (Value : char; Into : chars_ptr);
pragma Inline (Poke);
-- Given a chars_ptr, modify referenced Character value
function "+" (Left : chars_ptr; Right : size_t) return chars_ptr;
pragma Inline ("+");
-- Address arithmetic on chars_ptr value
function Position_Of_Nul (Into : char_array) return size_t;
-- Returns position of the first Nul in Into or Into'Last + 1 if none
-- We can't use directly System.Memory because the categorization is not
-- compatible, so we directly import here the malloc and free routines.
function Memory_Alloc (Size : size_t) return chars_ptr;
pragma Import (C, Memory_Alloc, System.Parameters.C_Malloc_Linkname);
procedure Memory_Free (Address : chars_ptr);
pragma Import (C, Memory_Free, "__gnat_free");
---------
-- "+" --
---------
function "+" (Left : chars_ptr; Right : size_t) return chars_ptr is
begin
return To_chars_ptr (To_Address (Left) + Storage_Offset (Right));
end "+";
----------
-- Free --
----------
procedure Free (Item : in out chars_ptr) is
begin
if Item = Null_Ptr then
return;
end if;
Memory_Free (Item);
Item := Null_Ptr;
end Free;
--------------------
-- New_Char_Array --
--------------------
function New_Char_Array (Chars : char_array) return chars_ptr is
Index : size_t;
Pointer : chars_ptr;
begin
-- Get index of position of null. If Index > Chars'Last,
-- nul is absent and must be added explicitly.
Index := Position_Of_Nul (Into => Chars);
Pointer := Memory_Alloc ((Index - Chars'First + 1));
-- If nul is present, transfer string up to and including nul
if Index <= Chars'Last then
Update (Item => Pointer,
Offset => 0,
Chars => Chars (Chars'First .. Index),
Check => False);
else
-- If original string has no nul, transfer whole string and add
-- terminator explicitly.
Update (Item => Pointer,
Offset => 0,
Chars => Chars,
Check => False);
Poke (nul, Into => Pointer + size_t'(Chars'Length));
end if;
return Pointer;
end New_Char_Array;
----------------
-- New_String --
----------------
function New_String (Str : String) return chars_ptr is
-- It's important that this subprogram uses the heap directly to compute
-- the result, and doesn't copy the string on the stack, otherwise its
-- use is limited when used from tasks on large strings.
Result : constant chars_ptr := Memory_Alloc (Str'Length + 1);
Result_Array : char_array (1 .. Str'Length + 1);
for Result_Array'Address use To_Address (Result);
pragma Import (Ada, Result_Array);
Count : size_t;
begin
To_C
(Item => Str,
Target => Result_Array,
Count => Count,
Append_Nul => True);
return Result;
end New_String;
----------
-- Peek --
----------
function Peek (From : chars_ptr) return char is
begin
return char (From.all);
end Peek;
----------
-- Poke --
----------
procedure Poke (Value : char; Into : chars_ptr) is
begin
Into.all := Character (Value);
end Poke;
---------------------
-- Position_Of_Nul --
---------------------
function Position_Of_Nul (Into : char_array) return size_t is
begin
for J in Into'Range loop
if Into (J) = nul then
return J;
end if;
end loop;
return Into'Last + 1;
end Position_Of_Nul;
------------
-- Strlen --
------------
function Strlen (Item : chars_ptr) return size_t is
Item_Index : size_t := 0;
begin
if Item = Null_Ptr then
raise Dereference_Error;
end if;
loop
if Peek (Item + Item_Index) = nul then
return Item_Index;
end if;
Item_Index := Item_Index + 1;
end loop;
end Strlen;
------------------
-- To_Chars_Ptr --
------------------
function To_Chars_Ptr
(Item : char_array_access;
Nul_Check : Boolean := False) return chars_ptr
is
begin
if Item = null then
return Null_Ptr;
elsif Nul_Check
and then Position_Of_Nul (Into => Item.all) > Item'Last
then
raise Terminator_Error;
else
return To_chars_ptr (Item (Item'First)'Address);
end if;
end To_Chars_Ptr;
------------
-- Update --
------------
procedure Update
(Item : chars_ptr;
Offset : size_t;
Chars : char_array;
Check : Boolean := True)
is
Index : chars_ptr := Item + Offset;
begin
if Check and then Offset + Chars'Length > Strlen (Item) then
raise Update_Error;
end if;
for J in Chars'Range loop
Poke (Chars (J), Into => Index);
Index := Index + size_t'(1);
end loop;
end Update;
procedure Update
(Item : chars_ptr;
Offset : size_t;
Str : String;
Check : Boolean := True)
is
begin
-- Note: in RM 95, the Append_Nul => False parameter is omitted. But
-- this has the unintended consequence of truncating the string after
-- an update. As discussed in Ada 2005 AI-242, this was unintended,
-- and should be corrected. Since this is a clear error, it seems
-- appropriate to apply the correction in Ada 95 mode as well.
Update (Item, Offset, To_C (Str, Append_Nul => False), Check);
end Update;
-----------
-- Value --
-----------
function Value (Item : chars_ptr) return char_array is
Result : char_array (0 .. Strlen (Item));
begin
if Item = Null_Ptr then
raise Dereference_Error;
end if;
-- Note that the following loop will also copy the terminating Nul
for J in Result'Range loop
Result (J) := Peek (Item + J);
end loop;
return Result;
end Value;
function Value
(Item : chars_ptr;
Length : size_t) return char_array
is
begin
if Item = Null_Ptr then
raise Dereference_Error;
end if;
-- ACATS cxb3010 checks that Constraint_Error gets raised when Length
-- is 0. Seems better to check that Length is not null before declaring
-- an array with size_t bounds of 0 .. Length - 1 anyway.
if Length = 0 then
raise Constraint_Error;
end if;
declare
Result : char_array (0 .. Length - 1);
begin
for J in Result'Range loop
Result (J) := Peek (Item + J);
if Result (J) = nul then
return Result (0 .. J);
end if;
end loop;
return Result;
end;
end Value;
function Value (Item : chars_ptr) return String is
begin
return To_Ada (Value (Item));
end Value;
function Value (Item : chars_ptr; Length : size_t) return String is
Result : char_array (0 .. Length);
begin
-- As per AI-00177, this is equivalent to:
-- To_Ada (Value (Item, Length) & nul);
if Item = Null_Ptr then
raise Dereference_Error;
end if;
for J in 0 .. Length - 1 loop
Result (J) := Peek (Item + J);
if Result (J) = nul then
return To_Ada (Result (0 .. J));
end if;
end loop;
Result (Length) := nul;
return To_Ada (Result);
end Value;
end Interfaces.C.Strings;