Im using inno setup to detect if .net 4.0 client installed but it doesn't work well

Question

When I install my program it checks to see if the .net 4.0 client is installed.

It not, then it should be installed.

The problem is that if I run the setup program again the installation file is trying to install the .Net 4.0 client again but this time it is giving me the option to repair or remove the .Net 4.0 client.

I don't know why in subsequent attempts it tries to install .Net again.

Another problem is that in the [Run] section I'm running ffdshow to install it in silent mode how can I check if it is already installed so not to install it again?

Here is my script:

; Script generated by the Inno Setup Script Wizard.
; SEE THE DOCUMENTATION FOR DETAILS ON CREATING INNO SETUP SCRIPT FILES!

#define MyAppName "Lightnings Extractor"
#define MyAppVersion "Lightnings Extractor 1.0"
#define MyAppExeName "Lightnings Extractor.exe"
#define FfdshowExeName "

[_ISTool]
EnableISX=true


[Setup]
; NOTE: The value of AppId uniquely identifies this application.
; Do not use the same AppId value in installers for other applications.
; (To generate a new GUID, click Tools | Generate GUID inside the IDE.)
AppId={{E60E9193-B054-4026-98EA-5DAD45CE9B0B}
AppName={#MyAppName}
AppVersion={#MyAppVersion}
;AppVerName={#MyAppName} {#MyAppVersion}
DefaultDirName={pf}\{#MyAppName}
DefaultGroupName={#MyAppName}
OutputDir=D:\Lightnings_Extractor Setup
OutputBaseFilename=LE_Setup
SetupIconFile=D:\MyWeatherStation-Images-And-Icons\Weather_Michmoret.ico
Compression=lzma
SolidCompression=yes
PrivilegesRequired=admin

[Languages]
Name: "english"; MessagesFile: "compiler:Default.isl"

[Tasks]
Name: "desktopicon"; Description: "{cm:CreateDesktopIcon}"; GroupDescription: "{cm:AdditionalIcons}"; Flags: unchecked

[Files]
Source: D:\Lightnings_Extractor Setup\Lightnings Extractor InnoSetup Script\isxdl\isxdl.dll; Flags: dontcopy
Source: "D:\C-Sharp\Extracting_Frames\Extracting_Frames\Extracting_Frames\bin\Release\Lightnings Extractor.exe"; DestDir: "{app}"; Flags: ignoreversion
Source: "D:\C-Sharp\Extracting_Frames\Extracting_Frames\Extracting_Frames\bin\Release\DirectShowLib-2005.dll"; DestDir: "{app}"; Flags: ignoreversion
Source: "D:\C-Sharp\Extracting_Frames\Extracting_Frames\Extracting_Frames\bin\Release\unfreez_wrapper.dll"; DestDir: "{app}"; Flags: ignoreversion
Source:  "D:\Appz\ffdshow_rev4225_20120105_clsid.exe"; DestDir: "{app}"; Flags: ignoreversion 
; NOTE: Don't use "Flags: ignoreversion" on any shared system files

[Messages]
WinVersionTooLowError=MyApp requires Windows NT4, Windows 98 or later.

[Icons]
Name: "{group}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"
Name: "{group}\{cm:UninstallProgram,{#MyAppName}}"; Filename: "{uninstallexe}"
Name: "{commondesktop}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"; Tasks: desktopicon

[Run]
Filename: "{app}\{#MyAppExeName}"; Description: "{cm:LaunchProgram,{#StringChange(MyAppName, '&', '&&')}}"; Flags: nowait postinstall skipifsilent
Filename: {app}\ffdshow_rev4225_20120105_clsid.exe; Parameters: /silent; StatusMsg: Installing ffdshow...

[Code]
var
  dotnetRedistPath: string;
  downloadNeeded: boolean;
  dotNetNeeded: boolean;
  memoDependenciesNeeded: string;

procedure isxdl_AddFile(URL, Filename: PChar);
external 'isxdl_AddFile@files:isxdl.dll stdcall';
function isxdl_DownloadFiles(hWnd: Integer): Integer;
external 'isxdl_DownloadFiles@files:isxdl.dll stdcall';
function isxdl_SetOption(Option, Value: PChar): Integer;
external 'isxdl_SetOption@files:isxdl.dll stdcall';


const
  dotnetRedistURL = 'http://www.microsoft.com/downloads/info.aspx?na=41&srcfamilyid=5765d7a8-7722-4888-a970-ac39b33fd8ab&srcdisplaylang=en&u=http%3a%2f%2fdownload.microsoft.com%2fdownload%2f7%2fB%2f6%2f7B629E05-399A-4A92-B5BC-484C74B5124B%2fdotNetFx40_Client_setup.exe';
  // local system for testing...    
  // dotnetRedistURL = 'http://192.168.1.1/dotnetfx.exe';

function InitializeSetup(): Boolean;

begin
  Result := true;
  dotNetNeeded := false;

  // Check for required netfx on windows xp installation
  if (not RegKeyExists(HKLM, 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4.0')) then begin
    dotNetNeeded := true;
    if (not IsAdminLoggedOn()) then begin
      MsgBox('MyApp needs the Microsoft .NET Framework to be installed by an Administrator', mbInformation, MB_OK);
      Result := false;
    end else begin
      memoDependenciesNeeded := memoDependenciesNeeded + '      .NET Framework' #13;
      dotnetRedistPath := ExpandConstant('{src}\dotnetfx.exe');
      if not FileExists(dotnetRedistPath) then begin
        dotnetRedistPath := ExpandConstant('{tmp}\dotnetfx.exe');
        if not FileExists(dotnetRedistPath) then begin
          isxdl_AddFile(dotnetRedistURL, dotnetRedistPath);
          downloadNeeded := true;
        end;
      end;
      SetIniString('install', 'dotnetRedist', dotnetRedistPath, ExpandConstant('{tmp}\dep.ini'));
    end;
  end;

end;

function NextButtonClick(CurPage: Integer): Boolean;
var
  hWnd: Integer;
  ResultCode: Integer;

begin
  Result := true;

  if CurPage = wpReady then begin

    hWnd := StrToInt(ExpandConstant('{wizardhwnd}'));

    // don't try to init isxdl if it's not needed because it will error on < ie 3
    if downloadNeeded then begin

      isxdl_SetOption('label', 'Downloading Microsoft .NET Framework');
      isxdl_SetOption('description', 'MyApp needs to install the Microsoft .NET Framework. Please wait while Setup is downloading extra files to your computer.');
      if isxdl_DownloadFiles(hWnd) = 0 then Result := false;
    end;
    if (Result = true) and (dotNetNeeded = true) then begin
      if Exec(ExpandConstant(dotnetRedistPath), '', '', SW_SHOW, ewWaitUntilTerminated, ResultCode) then begin
         // handle success if necessary; ResultCode contains the exit code
         if not (ResultCode = 0) then begin
           Result := false;
         end;
      end else begin
         // handle failure if necessary; ResultCode contains the error code
         Result := false;
      end;
    end;
  end;
end;

function UpdateReadyMemo(Space, NewLine, MemoUserInfoInfo, MemoDirInfo, MemoTypeInfo, MemoComponentsInfo, MemoGroupInfo, MemoTasksInfo: String): String;
var
  s: string;

begin
  if memoDependenciesNeeded <> '' then s := s + 'Dependencies to install:' + NewLine + memoDependenciesNeeded + NewLine;
  s := s + MemoDirInfo + NewLine + NewLine;

  Result := s
end;

//testing

function InitializeSetups(): Boolean;

begin
  Result := true;
  dotNetNeeded := false;

  // Check for required netfx on windows xp installation
  if (not RegKeyExists(HKLM, 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4')) then begin
    dotNetNeeded := true;
    if (not IsAdminLoggedOn()) then begin
      MsgBox('MyApp needs the Microsoft .NET Framework to be installed by an Administrator', mbInformation, MB_OK);
      Result := false;
    end else begin
      memoDependenciesNeeded := memoDependenciesNeeded + '      .NET Framework' #13;
      dotnetRedistPath := ExpandConstant('{src}\dotnetfx.exe');
      if not FileExists(dotnetRedistPath) then begin
        dotnetRedistPath := ExpandConstant('{tmp}\dotnetfx.exe');
        if not FileExists(dotnetRedistPath) then begin
          isxdl_AddFile(dotnetRedistURL, dotnetRedistPath);
          downloadNeeded := true;
        end;
      end;
      SetIniString('install', 'dotnetRedist', dotnetRedistPath, ExpandConstant('{tmp}\dep.ini'));
    end;
  end;

end;

function NextButtonClicks(CurPage: Integer): Boolean;
var
  hWnd: Integer;
  ResultCode: Integer;

begin
  Result := true;

  if CurPage = wpReady then begin

    hWnd := StrToInt(ExpandConstant('{wizardhwnd}'));

    // don't try to init isxdl if it's not needed because it will error on < ie 3
    if downloadNeeded then begin

      isxdl_SetOption('label', 'Downloading Microsoft .NET Framework');
      isxdl_SetOption('description', 'MyApp needs to install the Microsoft .NET Framework. Please wait while Setup is downloading extra files to your computer.');
      if isxdl_DownloadFiles(hWnd) = 0 then Result := false;
    end;
    if (Result = true) and (dotNetNeeded = true) then begin
      if Exec(ExpandConstant(dotnetRedistPath), '', '', SW_SHOW, ewWaitUntilTerminated, ResultCode) then begin
         // handle success if necessary; ResultCode contains the exit code
         if not (ResultCode = 0) then begin
           Result := false;
         end;
      end else begin
         // handle failure if necessary; ResultCode contains the error code
         Result := false;
      end;
    end;
  end;
end;

function UpdateReadyMemos(Space, NewLine, MemoUserInfoInfo, MemoDirInfo, MemoTypeInfo, MemoComponentsInfo, MemoGroupInfo, MemoTasksInfo: String): String;
var
  s: string;

begin
  if memoDependenciesNeeded <> '' then s := s + 'Dependencies to install:' + NewLine + memoDependenciesNeeded + NewLine;
  s := s + MemoDirInfo + NewLine + NewLine;

  Result := s
end;

Answer 1

What you need to do is Run a Code script in Inno and look for .Net 4 in the registry:

[Files]
;Redistributables
Source: Redistributables\*; DestDir: {tmp}; Flags: ignoreversion deleteafterinstall


[Code]
var dotNET40Missing: Boolean; // Is the .NET 4.0 Framework missing entirely?

function InitializeSetup(): Boolean;
begin
    // Test the presence of .NET 4.0
    if (not(RegKeyExists(HKLM, 'SOFTWARE\Microsoft\NET Framework Setup\NDP\v4'))) then
        dotNET40Missing := True;

    Result := True;
end;

function ShouldInstalldotNET40(): Boolean;
begin
    Result := dotNET40Missing;
end;

[Run]
Filename: {tmp}\.NET 4.0.exe; Description: Install Microsoft .Net Framework 4.0;    Parameters: /q /noreboot; Flags: skipifdoesntexist; Check: ShouldInstalldotNET40

The [Files] copies .Net WebInstaller to the temp directory. [Run] Installs .Net 4 if [Code] return true

EDIT

I noticed you had

if (not RegKeyExists(HKLM, 'HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4.0')

instead of

if (not RegKeyExists(HKLM, 'SOFTWARE\Microsoft\NET Framework Setup\NDP\v4.0')

Answer 2

There is an easy and robust way with the built-in function in Inno Setup:

IsDotNetInstalled()

Check the documentation here:

https://jrsoftware.org/ishelp/index.php?topic=isxfunc_isdotnetinstalled

Sample usage for your case:

Result := IsDotNetInstalled(net4Client, 0);