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Rework AWS client's API to avoid stressing too much the stack.
When sending large payload over a socket with AWS.Client.Post we ensure that no copy of the data is made on the stack to avoid a stack overflow. This is especially important when a call is made from a task where the stack may be limited. Add corresponding regression test. Fixes T527-014.
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6 files changed

+155
-17
lines changed

6 files changed

+155
-17
lines changed

‎regtests/0326_big_post/big_post.adb‎

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------------------------------------------------------------------------------
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-- Ada Web Server --
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-- --
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-- Copyright (C) 2020, AdaCore --
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-- --
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-- This is free software; you can redistribute it and/or modify it --
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-- under terms of the GNU General Public License as published by the --
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-- Free Software Foundation; either version 3, or (at your option) any --
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-- later version. This software is distributed in the hope that it will --
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-- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty --
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-- of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU --
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-- General Public License for more details. --
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-- --
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-- You should have received a copy of the GNU General Public License --
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-- distributed with this software; see file COPYING3. If not, go --
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-- to http://www.gnu.org/licenses for a complete copy of the license. --
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------------------------------------------------------------------------------
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with Ada.Streams;
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with Ada.Text_IO;
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with AWS.Client;
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with AWS.Messages;
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with AWS.MIME;
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with AWS.Net.Log;
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with AWS.Parameters;
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with AWS.Response;
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with AWS.Server.Status;
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with AWS.Status;
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with AWS.Translator;
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with AWS.Utils;
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procedure Big_Post is
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use Ada;
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use Ada.Streams;
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use AWS;
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type String_Access is access String;
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--------
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-- CB --
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--------
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function CB (Request : Status.Data) return Response.Data is
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begin
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Text_IO.Put_Line
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("Length payload: " & Status.Content_Length (Request)'Img);
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return Response.Build (MIME.Text_HTML, "ok");
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end CB;
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WS : Server.HTTP;
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M_Body : String_Access;
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R : Response.Data;
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begin
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Server.Start (WS, "Big Post", CB'Unrestricted_Access, Port => 0);
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Text_IO.Put_Line ("started");
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Text_IO.Flush;
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M_Body := new String'(1 .. 16_000_000 => 'a');
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R := Client.Post
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(Server.Status.Local_URL (WS) & "/big_post",
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M_Body.all,
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Content_Type => MIME.Text_HTML);
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Text_IO.Put_Line (Response.Message_Body (R));
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Server.Shutdown (WS);
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Text_IO.Put_Line ("shutdown");
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end Big_Post;

‎regtests/0326_big_post/big_post.gpr‎

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------------------------------------------------------------------------------
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-- Ada Web Server --
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-- --
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-- Copyright (C) 2020, AdaCore --
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-- --
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-- This is free software; you can redistribute it and/or modify it --
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-- under terms of the GNU General Public License as published by the --
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-- Free Software Foundation; either version 3, or (at your option) any --
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-- later version. This software is distributed in the hope that it will --
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-- be useful, but WITHOUT ANY WARRANTY; without even the implied warranty --
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-- of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU --
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-- General Public License for more details. --
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-- --
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-- You should have received a copy of the GNU General Public License --
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-- distributed with this software; see file COPYING3. If not, go --
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-- to http://www.gnu.org/licenses for a complete copy of the license. --
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------------------------------------------------------------------------------
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with "aws";
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project Big_Post is
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for Main use ("big_post.adb");
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end Big_Post;

‎regtests/0326_big_post/test.out‎

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started
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Length payload: 16000000
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ok
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shutdown

‎regtests/0326_big_post/test.py‎

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from test_support import *
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build_and_run('big_post');

‎src/core/aws-client.adb‎

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Original file line numberDiff line numberDiff line change
@@ -678,17 +678,47 @@ package body AWS.Client is
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Attachments : Attachment_List := Empty_Attachment_List;
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Headers : Header_List := Empty_Header_List) is
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begin
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Internal_Post
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(Connection,
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Result,
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Translator.To_Stream_Element_Array (Data),
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URI,
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SOAPAction => No_Data,
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Content_Type => (if Content_Type = No_Data
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then MIME.Application_Form_Data
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else Content_Type),
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Attachments => Attachments,
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Headers => Headers);
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-- For message larger than 20kb the conversion to Stream_Element_Array
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-- may create a stack overflow.
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if Data'Length > 20 * 1024 then
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declare
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SEA : Utils.Stream_Element_Array_Access :=
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Translator.To_Stream_Element_Array (Data);
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begin
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Internal_Post
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(Connection,
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Result,
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SEA.all,
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URI,
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SOAPAction => No_Data,
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Content_Type => (if Content_Type = No_Data
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then MIME.Application_Form_Data
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else Content_Type),
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Attachments => Attachments,
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Headers => Headers);
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Utils.Unchecked_Free (SEA);
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exception
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when others =>
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Utils.Unchecked_Free (SEA);
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raise;
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end;
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else
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Internal_Post
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(Connection,
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Result,
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Translator.To_Stream_Element_Array (Data),
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URI,
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SOAPAction => No_Data,
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Content_Type => (if Content_Type = No_Data
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then MIME.Application_Form_Data
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else Content_Type),
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Attachments => Attachments,
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Headers => Headers);
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end if;
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end Post;
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694724
---------

‎src/core/aws-net.adb‎

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Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
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------------------------------------------------------------------------------
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-- Ada Web Server --
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-- --
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-- Copyright (C) 2000-2019, AdaCore --
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-- Copyright (C) 2000-2020, AdaCore --
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-- --
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-- This library is free software; you can redistribute it and/or modify --
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-- it under terms of the GNU General Public License as published by the --
@@ -442,10 +442,12 @@ package body AWS.Net is
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(Socket : Socket_Type'Class; Data : Stream_Element_Array)
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is
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use Ada.Real_Time;
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Save : constant Boolean := Socket.C.Can_Wait;
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First : Stream_Element_Offset := Data'First;
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Last : Stream_Element_Offset;
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Stamp : Time;
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Chunk_Size : constant := 100 * 1_024;
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Save : constant Boolean := Socket.C.Can_Wait;
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First : Stream_Element_Offset := Data'First;
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Chunk_Last : Stream_Element_Offset := Data'Last;
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Last : Stream_Element_Offset;
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Stamp : Time;
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begin
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Socket.C.Can_Wait := True;
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@@ -466,7 +468,10 @@ package body AWS.Net is
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end if;
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loop
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Send (Socket, Data (First .. Data'Last), Last);
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Chunk_Last :=
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Stream_Element_Offset'Min (Data'Last, First + Chunk_Size - 1);
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Send (Socket, Data (First .. Chunk_Last), Last);
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exit when Last = Data'Last;
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