How can I log Inno Setup installations?

Question

Inno Setup has command line parameter /LOG="filename". Can I specify a log filename from inside the Inno Setup script, so I can include it later in my error reports?

Answer 1

You can set the SetupLogging option (SetupLogging=yes) then integrate the following code into your script to copy the log somewhere.

procedure CurStepChanged(CurStep: TSetupStep);
var
  logfilepathname, logfilename, newfilepathname: string;
begin
  logfilepathname := ExpandConstant('{log}');
  logfilename := ExtractFileName(logfilepathname);
  newfilepathname := ExpandConstant('{app}\') + logfilename;

  if CurStep = ssDone then
  begin
    FileCopy(logfilepathname, newfilepathname, false);
  end;
end; 

Answer 2

Following the comment from Lars I used the DeinitializeSetup() procedure, but I also changed the new file path to use the {src} constant to copy the log file to the directory that the installer is run from instead of {app} constant which may/may not be created if the user cancels the installation:

// Called just before Setup terminates. Note that this function is called even if the user exits Setup before anything is installed.
procedure DeinitializeSetup();
var
  logfilepathname, logfilename, newfilepathname: string;
begin
  logfilepathname := ExpandConstant('{log}');
  logfilename := ExtractFileName(logfilepathname);
  // Set the new target path as the directory where the installer is being run from
  newfilepathname := ExpandConstant('{src}\') + logfilename;

  FileCopy(logfilepathname, newfilepathname, false);
end; 

Answer 3

Extending the example from JasonMcF... checking if the uninstaller was created to see if the setup was finished successfully.

// Called just before Setup terminates.
// Note that this function is called even if the user exits Setup before anything is installed.
procedure DeinitializeSetup();
var
    unInstaller, logFilePath, logFileName, newFilePath: string;
begin
    unInstaller := ExpandConstant('{uninstallexe}');

    logFilePath := ExpandConstant('{log}');
    logFileName := ExtractFileName(logFilePath);
  
    if FileExists(unInstaller) then
    begin
        // uninstaller exists, setup was finished successfully, copy log to app directory
        newFilePath := ExpandConstant('{app}\') + logFileName;
    end
        else
    begin
        // setup didn't finish successfully, copy log to src directory
        newFilePath := ExpandConstant('{src}\') + logFileName;
    end;

    Log('DeinitializeSetup');
    Log('- unInstaller:' + unInstaller);
    Log('- logFilePath:' + logFilePath);
    Log('- newFilePath:' + newFilePath);

    FileCopy(logFilePath, newFilePath, false);
end;