------------------------------------------------------------------------------ -- -- -- 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 -- -- . -- -- -- -- 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;