freepascal.compiler/compiler/link.pas

{
    Copyright (c) 1998-2002 by Peter Vreman

    This unit handles the linker and binder calls for programs and
    libraries

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 ****************************************************************************
}
unit link;

{$i fpcdefs.inc}

interface
uses
  cclasses,
  systems,
  fmodule,
  globtype,
  ogbase;

Type
    TLinkerInfo=record
      ExeCmd,
      DllCmd        : array[1..3] of string;
      ResName       : string[100];
      ScriptName    : string[100];
      ExtraOptions  : string;
      DynamicLinker : string[100];
    end;

    TLinker = class(TAbstractLinker)
    private
       procedure AddProcdefImports(p:tnamedindexitem;arg:pointer);
    public
       HasResources,
       HasExports      : boolean;
       ObjectFiles,
       SharedLibFiles,
       StaticLibFiles  : TStringList;
       Constructor Create;virtual;
       Destructor Destroy;override;
       procedure AddModuleFiles(hp:tmodule);
       procedure AddExternalSymbol(const libname,symname:string);virtual;
       Procedure AddObject(const S,unitpath : String;isunit:boolean);
       Procedure AddStaticLibrary(const S : String);
       Procedure AddSharedLibrary(S : String);
       Procedure AddStaticCLibrary(const S : String);
       Procedure AddSharedCLibrary(S : String);
       Function  MakeExecutable:boolean;virtual;
       Function  MakeSharedLibrary:boolean;virtual;
       Function  MakeStaticLibrary:boolean;virtual;
       procedure ExpandAndApplyOrder(var Src:TStringList);
       procedure LoadPredefinedLibraryOrder;virtual; 
     end;

    TExternalLinker = class(TLinker)
    public
       Info : TLinkerInfo;
       Constructor Create;override;
       Destructor Destroy;override;
       Function  FindUtil(const s:string):String;
       Function  DoExec(const command:string; para:TCmdStr;showinfo,useshell:boolean):boolean;
       procedure SetDefaultInfo;virtual;
       Function  MakeStaticLibrary:boolean;override;
     end;

    TInternalLinker = class(TLinker)
    private
       FCExeOutput : TExeOutputClass;
       FCObjInput  : TObjInputClass;
       { Libraries }
       FExternalLibraryList : TFPHashObjectList;
       procedure Load_ReadObject(const para:string);
       procedure Load_ReadUnitObjects;
       procedure ParseScript_Load;
       procedure ParseScript_Order;
       procedure ParseScript_CalcPos;
       procedure PrintLinkerScript;
       function  RunLinkScript(const outputname:string):boolean;
    protected
       property CObjInput:TObjInputClass read FCObjInput write FCObjInput;
       property CExeOutput:TExeOutputClass read FCExeOutput write FCExeOutput;
       property ExternalLibraryList:TFPHashObjectList read FExternalLibraryList;
       procedure DefaultLinkScript;virtual;abstract;
       linkscript : TStringList;
    public
       IsSharedLibrary : boolean;
       Constructor Create;override;
       Destructor Destroy;override;
       Function  MakeExecutable:boolean;override;
       Function  MakeSharedLibrary:boolean;override;
       procedure AddExternalSymbol(const libname,symname:string);override;
     end;


var
  Linker  : TLinker;

function FindObjectFile(s : string;const unitpath:string;isunit:boolean) : string;
function FindLibraryFile(s:string;const prefix,ext:string;var foundfile : string) : boolean;
function FindDLL(const s:string;var founddll:string):boolean;

procedure InitLinker;
procedure DoneLinker;


Implementation

uses
{$IFDEF USE_SYSUTILS}
  SysUtils,
{$ELSE USE_SYSUTILS}
  dos,
{$ENDIF USE_SYSUTILS}
  cutils,
  script,globals,verbose,comphook,ppu,
  aasmbase,aasmtai,aasmdata,aasmcpu,
  symbase,symdef,symtype,symconst,
  ogmap;

type
 TLinkerClass = class of Tlinker;

{*****************************************************************************
                                   Helpers
*****************************************************************************}

{ searches an object file }
function FindObjectFile(s:string;const unitpath:string;isunit:boolean) : string;
var
  found : boolean;
  foundfile : string;
begin
  findobjectfile:='';
  if s='' then
   exit;

  {When linking on target, the units has not been assembled yet,
   so there is no object files to look for at
   the host. Look for the corresponding assembler file instead,
   because it will be assembled to object file on the target.}
  if isunit and (cs_link_on_target in aktglobalswitches) then
    s:= ForceExtension(s,target_info.asmext);

  { when it does not belong to the unit then check if
    the specified file exists without searching any paths }
  if not isunit then
   begin
     if FileExists(FixFileName(s)) then
      begin
        foundfile:=ScriptFixFileName(s);
        found:=true;
      end;
   end;
  if pos('.',s)=0 then
   s:=s+target_info.objext;
  { find object file
     1. output unit path
     2. output exe path
     3. specified unit path (if specified)
     4. cwd
     5. unit search path
     6. local object path
     7. global object path
     8. exepath (not when linking on target) }
  found:=false;
  if isunit and (OutputUnitDir<>'') then
    found:=FindFile(s,OutPutUnitDir,foundfile)
  else
    if OutputExeDir<>'' then
      found:=FindFile(s,OutPutExeDir,foundfile);
  if (not found) and (unitpath<>'') then
   found:=FindFile(s,unitpath,foundfile);
  if (not found) then
   found:=FindFile(s, CurDirRelPath(source_info), foundfile);
  if (not found) then
   found:=UnitSearchPath.FindFile(s,foundfile);
  if (not found) then
   found:=current_module.localobjectsearchpath.FindFile(s,foundfile);
  if (not found) then
   found:=objectsearchpath.FindFile(s,foundfile);
  if not(cs_link_on_target in aktglobalswitches) and (not found) then
   found:=FindFile(s,exepath,foundfile);
  if not(cs_link_nolink in aktglobalswitches) and (not found) then
   Message1(exec_w_objfile_not_found,s);

  {Restore file extension}
  if isunit and (cs_link_on_target in aktglobalswitches) then
    foundfile:= ForceExtension(foundfile,target_info.objext);

  findobjectfile:=ScriptFixFileName(foundfile);
end;


    { searches a (windows) DLL file }
    function FindDLL(const s:string;var founddll:string):boolean;
      var
        sysdir : string;
        Found : boolean;
      begin
        Found:=false;
        { Look for DLL in:
          1. Current dir
          2. Library Path
          3. windir,windir/system,windir/system32 }
        Found:=FindFile(s,'.'+source_info.DirSep,founddll);
        if (not found) then
         Found:=librarysearchpath.FindFile(s,founddll);
        if (not found) then
         begin
           {$IFDEF USE_SYSUTILS}
           sysdir:=FixPath(GetEnvironmentVariable('windir'),false);
           {$ELSE USE_SYSUTILS}
           sysdir:=FixPath(GetEnv('windir'),false);
           {$ENDIF USE_SYSUTILS}
           Found:=FindFile(s,sysdir+';'+sysdir+'system'+source_info.DirSep+';'+sysdir+'system32'+source_info.DirSep,founddll);
         end;
        if (not found) then
         begin
           message1(exec_w_libfile_not_found,s);
           FoundDll:=s;
         end;
        FindDll:=Found;
      end;


{ searches an library file }
function FindLibraryFile(s:string;const prefix,ext:string;var foundfile : string) : boolean;
var
  found : boolean;
  paths : string;
begin
  findlibraryfile:=false;
  foundfile:=s;
  if s='' then
   exit;
  { split path from filename }
  paths:=SplitPath(s);
  s:=SplitFileName(s);
  { add prefix 'lib' }
  if (prefix<>'') and (Copy(s,1,length(prefix))<>prefix) then
   s:=prefix+s;
  { add extension }
  if (ext<>'') and (Copy(s,length(s)-length(ext)+1,length(ext))<>ext) then
   s:=s+ext;
  { readd the split path }
  s:=paths+s;
  if FileExists(s) then
   begin
     foundfile:=ScriptFixFileName(s);
     FindLibraryFile:=true;
     exit;
   end;
  { find libary
     1. cwd
     2. local libary dir
     3. global libary dir
     4. exe path of the compiler (not when linking on target) }
  found:=FindFile(s, CurDirRelPath(source_info), foundfile);
  if (not found) and (current_module.outputpath^<>'') then
   found:=FindFile(s,current_module.outputpath^,foundfile);
  if (not found) then
   found:=current_module.locallibrarysearchpath.FindFile(s,foundfile);
  if (not found) then
   found:=librarysearchpath.FindFile(s,foundfile);
  if not(cs_link_on_target in aktglobalswitches) and (not found) then
   found:=FindFile(s,exepath,foundfile);
  foundfile:=ScriptFixFileName(foundfile);
  findlibraryfile:=found;
end;


{*****************************************************************************
                                   TLINKER
*****************************************************************************}

Constructor TLinker.Create;
begin
  Inherited Create;
  ObjectFiles:=TStringList.Create_no_double;
  SharedLibFiles:=TStringList.Create_no_double;
  StaticLibFiles:=TStringList.Create_no_double;
end;


Destructor TLinker.Destroy;
begin
  ObjectFiles.Free;
  SharedLibFiles.Free;
  StaticLibFiles.Free;
end;


procedure TLinker.AddProcdefImports(p:tnamedindexitem;arg:pointer);
begin
  if tdef(p).deftype<>procdef then
    exit;
  if assigned(tprocdef(p).import_dll) and
     assigned(tprocdef(p).import_name) then
    AddExternalSymbol(tprocdef(p).import_dll^,tprocdef(p).import_name^);
end;


procedure TLinker.AddModuleFiles(hp:tmodule);
var
  mask : longint;
begin
  with hp do
   begin
     if (flags and uf_has_resourcefiles)<>0 then
       HasResources:=true;
     if (flags and uf_has_exports)<>0 then
       HasExports:=true;
   { link unit files }
     if (flags and uf_no_link)=0 then
      begin
        { create mask which unit files need linking }
        mask:=link_always;
        { static linking ? }
        if (cs_link_static in aktglobalswitches) then
         begin
           if (flags and uf_static_linked)=0 then
            begin
              { if smart not avail then try static linking }
              if (flags and uf_smart_linked)<>0 then
               begin
                 Message1(exec_t_unit_not_static_linkable_switch_to_smart,modulename^);
                 mask:=mask or link_smart;
               end
              else
               Message1(exec_e_unit_not_smart_or_static_linkable,modulename^);
            end
           else
             mask:=mask or link_static;
         end;
        { smart linking ? }
        if (cs_link_smart in aktglobalswitches) then
         begin
           if (flags and uf_smart_linked)=0 then
            begin
              { if smart not avail then try static linking }
              if (flags and uf_static_linked)<>0 then
               begin
                 Message1(exec_t_unit_not_smart_linkable_switch_to_static,modulename^);
                 mask:=mask or link_static;
               end
              else
               Message1(exec_e_unit_not_smart_or_static_linkable,modulename^);
            end
           else
            mask:=mask or link_smart;
         end;
        { shared linking }
        if (cs_link_shared in aktglobalswitches) then
         begin
           if (flags and uf_shared_linked)=0 then
            begin
              { if shared not avail then try static linking }
              if (flags and uf_static_linked)<>0 then
               begin
                 Message1(exec_t_unit_not_shared_linkable_switch_to_static,modulename^);
                 mask:=mask or link_static;
               end
              else
               Message1(exec_e_unit_not_shared_or_static_linkable,modulename^);
            end
           else
            mask:=mask or link_shared;
         end;
        { unit files }
        while not linkunitofiles.empty do
          AddObject(linkunitofiles.getusemask(mask),path^,true);
        while not linkunitstaticlibs.empty do
          AddStaticLibrary(linkunitstaticlibs.getusemask(mask));
        while not linkunitsharedlibs.empty do
          AddSharedLibrary(linkunitsharedlibs.getusemask(mask));
      end;
     { Other needed .o and libs, specified using $L,$LINKLIB,external }
     mask:=link_always;
     while not linkotherofiles.empty do
      AddObject(linkotherofiles.Getusemask(mask),path^,false);
     while not linkotherstaticlibs.empty do
      AddStaticCLibrary(linkotherstaticlibs.Getusemask(mask));
     while not linkothersharedlibs.empty do
      AddSharedCLibrary(linkothersharedlibs.Getusemask(mask));
     { Known Library/DLL Imports }
     if assigned(globalsymtable) then
       globalsymtable.defindex.foreach(@AddProcdefImports,nil);
     if assigned(localsymtable) then
       localsymtable.defindex.foreach(@AddProcdefImports,nil);
   end;
end;


    procedure TLinker.AddExternalSymbol(const libname,symname:string);
      begin
      end;


Procedure TLinker.AddObject(const S,unitpath : String;isunit:boolean);
begin
  ObjectFiles.Concat(FindObjectFile(s,unitpath,isunit));
end;


Procedure TLinker.AddSharedLibrary(S:String);
begin
  if s='' then
   exit;
{ remove prefix 'lib' }
  if Copy(s,1,length(target_info.sharedlibprefix))=target_info.sharedlibprefix then
   Delete(s,1,length(target_info.sharedlibprefix));
{ remove extension if any }
  if Copy(s,length(s)-length(target_info.sharedlibext)+1,length(target_info.sharedlibext))=target_info.sharedlibext then
   Delete(s,length(s)-length(target_info.sharedlibext)+1,length(target_info.sharedlibext)+1);
{ ready to be added }
  SharedLibFiles.Concat(S);
end;


Procedure TLinker.AddStaticLibrary(const S:String);
var
  ns : string;
  found : boolean;
begin
  if s='' then
   exit;
  found:=FindLibraryFile(s,target_info.staticlibprefix,target_info.staticlibext,ns);
  if not(cs_link_nolink in aktglobalswitches) and (not found) then
   Message1(exec_w_libfile_not_found,s);
  StaticLibFiles.Concat(ns);
end;


Procedure TLinker.AddSharedCLibrary(S:String);
begin
  if s='' then
   exit;
{ remove prefix 'lib' }
  if Copy(s,1,length(target_info.sharedclibprefix))=target_info.sharedclibprefix then
   Delete(s,1,length(target_info.sharedclibprefix));
{ remove extension if any }
  if Copy(s,length(s)-length(target_info.sharedclibext)+1,length(target_info.sharedclibext))=target_info.sharedclibext then
   Delete(s,length(s)-length(target_info.sharedclibext)+1,length(target_info.sharedclibext)+1);
{ ready to be added }
  SharedLibFiles.Concat(S);
end;


Procedure TLinker.AddStaticCLibrary(const S:String);
var
  ns : string;
  found : boolean;
begin
  if s='' then
   exit;
  found:=FindLibraryFile(s,target_info.staticclibprefix,target_info.staticclibext,ns);
  if not(cs_link_nolink in aktglobalswitches) and (not found) then
   Message1(exec_w_libfile_not_found,s);
  StaticLibFiles.Concat(ns);
end;


function TLinker.MakeExecutable:boolean;
begin
  MakeExecutable:=false;
  Message(exec_e_exe_not_supported);
end;


Function TLinker.MakeSharedLibrary:boolean;
begin
  MakeSharedLibrary:=false;
  Message(exec_e_dll_not_supported);
end;


Function TLinker.MakeStaticLibrary:boolean;
begin
  MakeStaticLibrary:=false;
  Message(exec_e_dll_not_supported);
end;

Procedure TLinker.ExpandAndApplyOrder(var Src:TStringList);

var p : TLinkStrMap;
    i : Integer;
begin
  // call Virtual TLinker method to initialize
  LoadPredefinedLibraryOrder;

  // something to do?
  if (LinkLibraryAliases.count=0) and (LinkLibraryOrder.Count=0) Then 
    exit;
  p:=TLinkStrMap.Create;
  
  // expand libaliases, clears src
  LinkLibraryAliases.expand(src,p);
  
  // apply order
  p.UpdateWeights(LinkLibraryOrder);  
  p.SortOnWeight;
  
  // put back in src
  for i:=0 to p.count-1 do
    src.insert(p[i].Key);
  p.free;
end;

procedure TLinker.LoadPredefinedLibraryOrder;

begin
end;

{*****************************************************************************
                              TEXTERNALLINKER
*****************************************************************************}

Constructor TExternalLinker.Create;
begin
  inherited Create;
  { set generic defaults }
  FillChar(Info,sizeof(Info),0);
  if cs_link_on_target in aktglobalswitches then
    begin
      Info.ResName:=outputexedir+inputfile+'_link.res';
      Info.ScriptName:=outputexedir+inputfile+'_script.res';
    end
  else
    begin
      Info.ResName:='link.res';
      Info.ScriptName:='script.res';
    end;
  { set the linker specific defaults }
  SetDefaultInfo;
  { Allow Parameter overrides for linker info }
  with Info do
   begin
     if ParaLinkOptions<>'' then
      ExtraOptions:=ParaLinkOptions;
     if ParaDynamicLinker<>'' then
      DynamicLinker:=ParaDynamicLinker;
   end;
end;


Destructor TExternalLinker.Destroy;
begin
  inherited destroy;
end;


Procedure TExternalLinker.SetDefaultInfo;
begin
end;


Function TExternalLinker.FindUtil(const s:string):string;
var
  Found    : boolean;
  FoundBin : string;
  UtilExe  : string;
begin
  if cs_link_on_target in aktglobalswitches then
    begin
      { If linking on target, don't add any path PM }
      FindUtil:=AddExtension(s,target_info.exeext);
      exit;
    end;
  UtilExe:=AddExtension(s,source_info.exeext);
  FoundBin:='';
  Found:=false;
  if utilsdirectory<>'' then
   Found:=FindFile(utilexe,utilsdirectory,Foundbin);
  if (not Found) then
   Found:=FindExe(utilexe,Foundbin);
  if (not Found) and not(cs_link_nolink in aktglobalswitches) then
   begin
     Message1(exec_e_util_not_found,utilexe);
     aktglobalswitches:=aktglobalswitches+[cs_link_nolink];
   end;
  if (FoundBin<>'') then
   Message1(exec_t_using_util,FoundBin);
  FindUtil:=FoundBin;
end;


Function TExternalLinker.DoExec(const command:string; para:TCmdStr;showinfo,useshell:boolean):boolean;
var
  exitcode: longint;
begin
  DoExec:=true;
  if not(cs_link_nolink in aktglobalswitches) then
   begin
     FlushOutput;
     if useshell then
       exitcode := shell(maybequoted(command)+' '+para)
     else
{$IFDEF USE_SYSUTILS}
     try
       if ExecuteProcess(command,para) <> 0
       then begin
         Message(exec_e_error_while_linking);
         aktglobalswitches:=aktglobalswitches+[cs_link_nolink];
         DoExec:=false;
       end;
     except on E:EOSError do
       begin
         Message(exec_e_cant_call_linker);
         aktglobalswitches:=aktglobalswitches+[cs_link_nolink];
         DoExec:=false;
       end;
     end
   end;
{$ELSE USE_SYSUTILS}
       begin
         swapvectors;
         exec(command,para);
         swapvectors;
         exitcode := dosexitcode;
       end;
     if (doserror<>0) then
      begin
         Message(exec_e_cant_call_linker);
         aktglobalswitches:=aktglobalswitches+[cs_link_nolink];
         DoExec:=false;
      end
     else
      if (exitcode<>0) then
       begin
        Message(exec_e_error_while_linking);
        aktglobalswitches:=aktglobalswitches+[cs_link_nolink];
        DoExec:=false;
       end;
   end;
{$ENDIF USE_SYSUTILS}
{ Update asmres when externmode is set }
  if cs_link_nolink in aktglobalswitches then
   begin
     if showinfo then
       begin
         if DLLsource then
           AsmRes.AddLinkCommand(Command,Para,current_module.sharedlibfilename^)
         else
           AsmRes.AddLinkCommand(Command,Para,current_module.exefilename^);
       end
     else
      AsmRes.AddLinkCommand(Command,Para,'');
   end;
end;


Function TExternalLinker.MakeStaticLibrary:boolean;

  function GetNextFiles(const maxCmdLength : AInt; var item : TStringListItem) : string;
    begin
      result := '';
      while (assigned(item) and ((length(result) + length(item.str) + 1) < maxCmdLength)) do begin
        result := result + ' ' + item.str;
        item := TStringListItem(item.next);
      end;
    end;

var
  binstr, scriptfile : string;
  success : boolean;
  cmdstr, nextcmd, smartpath : TCmdStr;
  current : TStringListItem;
  script: Text;
  scripted_ar : boolean;
begin
  MakeStaticLibrary:=false;
{ remove the library, to be sure that it is rewritten }
  RemoveFile(current_module.staticlibfilename^);
{ Call AR }
  smartpath:=current_module.outputpath^+FixPath(current_module.newfilename^+target_info.smartext,false);
  SplitBinCmd(target_ar.arcmd,binstr,cmdstr);
  binstr := FindUtil(utilsprefix + binstr);


  scripted_ar:=target_ar.id=ar_gnu_ar_scripted;

  if scripted_ar then
    begin
      scriptfile := FixFileName(smartpath+'arscript.txt');
      Replace(cmdstr,'$SCRIPT',maybequoted(scriptfile));
      Assign(script, scriptfile);
      Rewrite(script);
      try
        writeln(script, 'CREATE ' + current_module.staticlibfilename^);
        current := TStringListItem(SmartLinkOFiles.First);
        while current <> nil do
          begin
            writeln(script, 'ADDMOD ' + current.str);
            current := TStringListItem(current.next);
          end;
        writeln(script, 'SAVE');
        writeln(script, 'END');
      finally
        Close(script);
      end;
      success:=DoExec(binstr,cmdstr,false,true);
    end
  else
    begin
      Replace(cmdstr,'$LIB',maybequoted(current_module.staticlibfilename^));
      { create AR commands }
      success := true;
      nextcmd := cmdstr;
      current := TStringListItem(SmartLinkOFiles.First);
      repeat
        Replace(nextcmd,'$FILES',GetNextFiles(240 - length(nextcmd) + 6 - length(binstr) - 1, current));
        success:=DoExec(binstr,nextcmd,false,true);
        nextcmd := cmdstr;
      until (not assigned(current)) or (not success);
    end;

  if (target_ar.arfinishcmd <> '') then
    begin
      SplitBinCmd(target_ar.arfinishcmd,binstr,cmdstr);
      Replace(cmdstr,'$LIB',maybequoted(current_module.staticlibfilename^));
      success:=DoExec(binstr,cmdstr,false,true);
    end;

  { Clean up }
  if not(cs_asm_leave in aktglobalswitches) then
   if not(cs_link_nolink in aktglobalswitches) then
    begin
      while not SmartLinkOFiles.Empty do
        RemoveFile(SmartLinkOFiles.GetFirst);
      if scripted_ar then
        RemoveFile(scriptfile);
      RemoveDir(smartpath);
    end
   else
    begin
      AsmRes.AddDeleteCommand(FixFileName(smartpath+current_module.asmprefix^+'*'+target_info.objext));
      if scripted_ar then
        AsmRes.AddDeleteCommand(scriptfile);
      AsmRes.Add('rmdir '+smartpath);
    end;
  MakeStaticLibrary:=success;
end;


{*****************************************************************************
                              TINTERNALLINKER
*****************************************************************************}

    Constructor TInternalLinker.Create;
      begin
        inherited Create;
        linkscript:=TStringList.Create;
        FExternalLibraryList:=TFPHashObjectList.Create(true);
        exemap:=nil;
        exeoutput:=nil;
        CObjInput:=TObjInput;
      end;


    Destructor TInternalLinker.Destroy;
      begin
        linkscript.free;
        ExternalLibraryList.Free;
        if assigned(exeoutput) then
          begin
            exeoutput.free;
            exeoutput:=nil;
          end;
        if assigned(exemap) then
          begin
            exemap.free;
            exemap:=nil;
          end;
        inherited destroy;
      end;


    procedure TInternalLinker.AddExternalSymbol(const libname,symname:string);
      var
        ExtLibrary : TExternalLibrary;
        ExtSymbol : TFPHashObject;
      begin
        ExtLibrary:=TExternalLibrary(ExternalLibraryList.Find(libname));
        if not assigned(ExtLibrary) then
          ExtLibrary:=TExternalLibrary.Create(ExternalLibraryList,libname);
        ExtSymbol:=TFPHashObject(ExtLibrary.ExternalSymbolList.Find(symname));
        if not assigned(ExtSymbol) then
          ExtSymbol:=TFPHashObject.Create(ExtLibrary.ExternalSymbolList,symname);
      end;


    procedure TInternalLinker.Load_ReadObject(const para:string);
      var
        objdata  : TObjData;
        objinput : TObjinput;
        fn       : string;
      begin
        fn:=FindObjectFile(para,'',false);
        Comment(V_Tried,'Reading object '+fn);
        objinput:=CObjInput.Create;
        objdata:=objinput.newObjData(para);
        if objinput.readobjectfile(fn,objdata) then
          exeoutput.addobjdata(objdata);
        { release input object }
        objinput.free;
      end;


    procedure TInternalLinker.Load_ReadUnitObjects;
      var
        s : string;
      begin
        while not ObjectFiles.Empty do
          begin
            s:=ObjectFiles.GetFirst;
            if s<>'' then
              Load_ReadObject(s);
          end;
      end;


    procedure TInternalLinker.ParseScript_Load;
      var
        s,
        para,
        keyword : string;
        hp : TStringListItem;
      begin
        exeoutput.Load_Start;
        hp:=tstringlistitem(linkscript.first);
        while assigned(hp) do
          begin
            s:=hp.str;
            if (s='') or (s[1]='#') then
              continue;
            keyword:=Upper(GetToken(s,' '));
            para:=GetToken(s,' ');
            if keyword='SYMBOL' then
              ExeOutput.Load_Symbol(para)
            else if keyword='ENTRYNAME' then
              ExeOutput.Load_EntryName(para)
            else if keyword='ISSHAREDLIBRARY' then
              ExeOutput.Load_IsSharedLibrary
            else if keyword='IMAGEBASE' then
              ExeOutput.Load_ImageBase(para)
            else if keyword='READOBJECT' then
              Load_ReadObject(para)
            else if keyword='READUNITOBJECTS' then
              Load_ReadUnitObjects;
            hp:=tstringlistitem(hp.next);
          end;
      end;


    procedure TInternalLinker.ParseScript_Order;
      var
        s,
        para,
        keyword : string;
        hp : TStringListItem;
      begin
        exeoutput.Order_Start;
        hp:=tstringlistitem(linkscript.first);
        while assigned(hp) do
          begin
            s:=hp.str;
            if (s='') or (s[1]='#') then
              continue;
            keyword:=Upper(GetToken(s,' '));
            para:=GetToken(s,' ');
            if keyword='EXESECTION' then
              ExeOutput.Order_ExeSection(para)
            else if keyword='ENDEXESECTION' then
              ExeOutput.Order_EndExeSection
            else if keyword='OBJSECTION' then
              ExeOutput.Order_ObjSection(para)
            else if keyword='ZEROS' then
              ExeOutput.Order_Zeros(para)
            else if keyword='SYMBOL' then
              ExeOutput.Order_Symbol(para);
            hp:=tstringlistitem(hp.next);
          end;
        exeoutput.Order_End;
      end;


    procedure TInternalLinker.ParseScript_CalcPos;
      var
        s,
        para,
        keyword : string;
        hp : TStringListItem;
      begin
        exeoutput.CalcPos_Start;
        hp:=tstringlistitem(linkscript.first);
        while assigned(hp) do
          begin
            s:=hp.str;
            if (s='') or (s[1]='#') then
              continue;
            keyword:=Upper(GetToken(s,' '));
            para:=GetToken(s,' ');
            if keyword='EXESECTION' then
              ExeOutput.CalcPos_ExeSection(para)
            else if keyword='ENDEXESECTION' then
              ExeOutput.CalcPos_EndExeSection
            else if keyword='HEADER' then
              ExeOutput.CalcPos_Header
            else if keyword='SYMBOLS' then
              ExeOutput.CalcPos_Symbols;
            hp:=tstringlistitem(hp.next);
          end;
      end;


    procedure TInternalLinker.PrintLinkerScript;
      var
        hp : TStringListItem;
      begin
        if not assigned(exemap) then
          exit;
        exemap.Add('Used linker script');
        exemap.Add('');
        hp:=tstringlistitem(linkscript.first);
        while assigned(hp) do
          begin
            exemap.Add(hp.str);
            hp:=tstringlistitem(hp.next);
          end;
      end;


    function TInternalLinker.RunLinkScript(const outputname:string):boolean;
      label
        myexit;
      begin
        result:=false;

        Message1(exec_i_linking,outputname);

{$warning TODO Load custom linker script}
        DefaultLinkScript;

        exeoutput:=CExeOutput.Create;

        if (cs_link_map in aktglobalswitches) then
          exemap:=texemap.create(current_module.mapfilename^);

        PrintLinkerScript;

        { Load .o files and resolve symbols }
        ParseScript_Load;
        exeoutput.ResolveSymbols;
        { Generate symbols and code to do the importing }
        exeoutput.GenerateLibraryImports(ExternalLibraryList);
        { Fill external symbols data }
        exeoutput.FixupSymbols;
        if ErrorCount>0 then
          goto myexit;

        { Create .exe sections and add .o sections }
        ParseScript_Order;
        exeoutput.RemoveUnreferencedSections;
        exeoutput.MergeStabs;
        exeoutput.RemoveEmptySections;
        if ErrorCount>0 then
          goto myexit;

        { Calc positions in mem and file }
        ParseScript_CalcPos;
        exeoutput.FixupRelocations;
        exeoutput.PrintMemoryMap;
        if ErrorCount>0 then
          goto myexit;

        exeoutput.WriteExeFile(outputname);

{$warning TODO fixed section names}
        status.codesize:=exeoutput.findexesection('.text').size;
        status.datasize:=exeoutput.findexesection('.data').size;

      myexit:
        { close map }
        if assigned(exemap) then
          begin
            exemap.free;
            exemap:=nil;
          end;

        { close exe }
        exeoutput.free;
        exeoutput:=nil;

        result:=true;
      end;


    function TInternalLinker.MakeExecutable:boolean;
      begin
        IsSharedLibrary:=false;
        result:=RunLinkScript(current_module.exefilename^);
      end;


    function TInternalLinker.MakeSharedLibrary:boolean;
      begin
        IsSharedLibrary:=true;
        result:=RunLinkScript(current_module.sharedlibfilename^);
      end;


{*****************************************************************************
                                 Init/Done
*****************************************************************************}

    procedure InitLinker;
      var
        lk : TlinkerClass;
      begin
        if (cs_link_extern in aktglobalswitches) and
           assigned(target_info.linkextern) then
          begin
            lk:=TlinkerClass(target_info.linkextern);
            linker:=lk.Create;
          end
        else
          if assigned(target_info.link) then
            begin
              lk:=TLinkerClass(target_info.link);
              linker:=lk.Create;
            end
        else
          linker:=Tlinker.Create;
      end;


    procedure DoneLinker;
      begin
        if assigned(linker) then
         Linker.Free;
      end;


{*****************************************************************************
                                   Initialize
*****************************************************************************}

    const
      ar_gnu_ar_info : tarinfo =
          (
            id          : ar_gnu_ar;
            arcmd       : 'ar qS $LIB $FILES';
            arfinishcmd : 'ar s $LIB'
          );

      ar_gnu_ar_scripted_info : tarinfo =
          (
            id    : ar_gnu_ar_scripted;
            arcmd : 'ar -M < $SCRIPT';
            arfinishcmd : ''
          );

initialization
  RegisterAr(ar_gnu_ar_info);
  RegisterAr(ar_gnu_ar_scripted_info);
end.