Question

What is the proper way to detect if the Lazarus IDE is installed in a system programmatically using Delphi?

For example to detect if Delphi 7 is installed I can check this key HKLM\Software\Borland\Delphi\7.0.

I search for a similar key for Lazarus in the Windows registry but I don’t found anything.

Answer 1

Lazarus store a file called environmentoptions.xml by default in the <user name>\Local Settings\Application Data\lazarus folder (in some scenarios this file can be located in other folder). This file contains all the info necessary to get the Lazarus IDE location as well the FPC (Free Pascal compiler) used by the IDE.

the environmentoptions.xml file look like this

<?xml version="1.0"?>
<CONFIG>
  <EnvironmentOptions>
    <Version Value="106"/>
    <LazarusDirectory Value="C:\lazarus\">
      <History Count="1">
        <Item1 Value="C:\lazarus\"/>
      </History>
    </LazarusDirectory>
    <CompilerFilename Value="C:\lazarus\fpc\2.2.4\bin\i386-win32\fpc.exe">
      <History Count="3">
        <Item1 Value="C:\fpc\2.2.4\bin\i386-win32\fpc.exe"/>
        <Item2 Value="C:\lazarus\fpc\2.2.4\bin\i386-win32\fpc.exe"/>
        <Item3 Value="C:\lazarus\fpc\2.4.2\bin\i386-win32\fpc.exe"/>
      </History>
    </CompilerFilename>
    <FPCSourceDirectory Value="c:\lazarus\fpc\2.2.4\source\">
      <History Count="1">
        <Item1 Value="c:\lazarus\fpc\2.2.4\source\"/>
      </History>
    </FPCSourceDirectory>
    <MakeFilename Value="C:\lazarus\fpc\2.2.4\bin\i386-win32\make.exe">
      <History Count="2">
        <Item1 Value="C:\fpc\2.2.4\bin\i386-win32\make.exe"/>
        <Item2 Value="C:\lazarus\fpc\2.2.4\bin\i386-win32\make.exe"/>
      </History>
    </MakeFilename>
    <TestBuildDirectory Value="C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\">
      <History Count="3">
        <Item1 Value="C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\"/>
        <Item2 Value="C:\temp\"/>
        <Item3 Value="C:\windows\temp\"/>
      </History>
    </TestBuildDirectory>
    <BackupProjectFiles AdditionalExtension="bak" MaxCounter="9"/>
    <BackupOtherFiles AdditionalExtension="bak" MaxCounter="9"/>
    <Debugger Class="TGDBMIDebugger" EventLogLineLimit="100"/>
    <DebuggerFilename Value="c:\lazarus\mingw\bin\gdb.exe">
      <History Count="4">
        <Item1 Value="c:\lazarus\mingw\bin\gdb.exe"/>
        <Item2 Value="/usr/bin/gdb"/>
        <Item3 Value="/usr/local/bin/gdb"/>
        <Item4 Value="/opt/fpc/gdb"/>
      </History>
    </DebuggerFilename>
    <Recent>
      <OpenFiles Max="10" Count="10">
      </OpenFiles>
      <ProjectFiles Max="5" Count="5">
      </ProjectFiles>
      <PackageFiles Max="10" Count="1">
        <Item1 Value="C:\Librerias\Indy10\Lib\indylaz.lpk"/>
      </PackageFiles>
    </Recent>
    <ExternalTools Count="0"/>
    <CharcaseFileAction Value="Ask"/>
    <CompilerMessagesFilename Value=""/>
  </EnvironmentOptions>
  <ObjectInspectorOptions ShowHints="False" InfoBoxHeight="50">
    <Version Value="3"/>
    <ComponentTree>
      <Height Value="97"/>
    </ComponentTree>
  </ObjectInspectorOptions>
</CONFIG>

so the steps necessaries to determine if the Lazarus IDE is installed in a Windows system are

1. Determine the location of the <user name>\Local Settings\Application Data\lazarus using the SHGetSpecialFolderLocation function with the CSIDL_LOCAL_APPDATA value.

2. Parse the file environmentoptions.xml to locate the LazarusDirectory Key under the EnvironmentOptions root.

3. Now with the location of the Lazarus IDE you can check the existence of the lazarus.exe file in that folder.

check this sample application which summarize all steps in this answer.

{$APPTYPE CONSOLE}

uses
  ShlObj,
  ComObj,
  ActiveX,
  Classes,
  Windows,
  Variants,
  SysUtils;

function GetLocalAppDataFolder : string;
const
  CSIDL_LOCAL_APPDATA        = $001C;
var
  ppMalloc   : IMalloc;
  ppidl      : PItemIdList;
begin
  ppidl := nil;
  try
    if SHGetMalloc(ppMalloc) = S_OK then
    begin
      SHGetSpecialFolderLocation(0, CSIDL_LOCAL_APPDATA, ppidl);
      SetLength(Result, MAX_PATH);
      if not SHGetPathFromIDList(ppidl, PChar(Result)) then
        RaiseLastOSError;
      SetLength(Result, lStrLen(PChar(Result)));
    end;
  finally
   if ppidl <> nil then
         ppMalloc.free(ppidl);
  end;
end;


function GetLazarusLocalFolder : string;
begin
 Result:=Format('%slazarus',[IncludeTrailingPathDelimiter(GetLocalAppDataFolder)]);
 if not DirectoryExists(Result) then
 Result:='';
end;


function FileToString(const FileName: TFileName): AnsiString;
var
   Stream : TFileStream;
begin
  Stream:=TFileStream.Create(FileName, fmOpenRead or fmShareDenyWrite);
  try
      try
        SetLength(Result, Stream.Size);
        Stream.Read(Pointer(Result)^, Stream.Size);
      except
        Result:='';
      end;
  finally
     Stream.Free;
  end;
end;

function GetLazarusFolder : string;
var
   LocalFolder : TFileName;
   FileName    : TFileName;
   XmlDoc      : OleVariant;
   Node        : OleVariant;
begin
  Result:='';
  LocalFolder:=GetLazarusLocalFolder;
  if LocalFolder<>'' then
  begin
   FileName:=IncludeTrailingPathDelimiter(LocalFolder)+'environmentoptions.xml';
   if FileExists(FileName) then
   begin
     XmlDoc       := CreateOleObject('Msxml2.DOMDocument.6.0');
     try
       XmlDoc.Async := False;
       XmlDoc.LoadXML(FileToString(FileName));
       XmlDoc.SetProperty('SelectionLanguage','XPath');

        if (XmlDoc.parseError.errorCode <> 0) then
         raise Exception.CreateFmt('Error in Xml Data %s',[XmlDoc.parseError]);

       Node  :=XmlDoc.selectSingleNode('//CONFIG/EnvironmentOptions/LazarusDirectory/@Value');
       if not VarIsClear(Node) then
       Result:=Node.text;
     finally
       XmlDoc:=Unassigned;
     end;
   end;
  end;
end;


function IsLazarusInstalled : Boolean;
begin
  Result:=FileExists(IncludeTrailingPathDelimiter(GetLazarusFolder)+'lazarus.exe');
end;

begin
 try
    CoInitialize(nil);
    try
      Writeln('Lazarus config Folder  '+GetLazarusLocalFolder);
      Writeln('Lazarus Install folder '+GetLazarusFolder);
      Writeln('Is Lazarus Installed   '+BoolToStr(IsLazarusInstalled,True));
      Readln;
    finally
      CoUninitialize;
    end;
 except
    on E:Exception do
    begin
        Writeln(E.Classname, ':', E.Message);
        Readln;
    end;
  end;
end.