Question

This is a question I intend to answer myself, but please feel free to add other ways to accomplish this.

I was packaging an application for use on a wide variety of configurations, and I determined that the most reliable way to perform custom logic within my MSI would be to write my own custom action DLL that would be able to read/write from the PROPERTY table, kill a process, determine if an application needed to be upgraded (and then record the answer in the PROPERTY table), and write to the standard MSI log.

Answer 1

My solution is in Delphi, and requires the open-source JEDI API translations that you can download here. One problem that I have found is that examples for using the JwaMSI headers are few and far between. Hopefully someone will find this as a useful example.

Here is the main unit, with a 2nd supporting unit following it (that you can include in the same DLL project). Simply create a new DLL (library) in Delphi, and copy/paste this code. This unit exports 2 functions that are callable from the MSI. They are:

1. CheckIfUpgradeable
2. KillRunningApp

Both of these functions read a PROPERTY value from the property table, and set a value when the complete. The idea is that then a 2nd custom action can read this property and throw an error, or use it as an install condition.

This code is more for an example, and in this example below it is checking to see if the version of ‘notepad.exe’ needs to be upgraded (that means the version stored in the property table value ‘NOTEPAD_VERSON’ is greater than the version of notepad.exe on the system). If it is not, then it sets the property of ‘UPGRADEABLE_VERSION’ to ‘NO’ (this property is set to ‘YES’ by default).

This code also looks in the PROPERTY table for ‘PROGRAM_TO_KILL’ and will kill that program if it is running. It needs to include the file extension of the program to kill, e.g. ‘Notepad.exe’

library MsiHelper;  uses   Windows,   SysUtils,   Classes,   StrUtils,   jwaMSI,   jwaMSIDefs,   jwaMSIQuery,   JclSysInfo,   PsApi,   MSILogging in 'MSILogging.pas';  {$R *.res}   function CompareVersionNumbers(AVersion1, AVersion2: string): Integer; var   N1, N2: Integer; //Returns 1 if AVersion1 < AVersion2 //Returns -1 if AVersion1 > AVersion2 //Returns 0 if values are equal   function GetNextNumber(var Version: string): Integer;   var     P: Integer;     S: string;   begin     P := Pos('.', Version);     if P > 0 then     begin       S := Copy(Version, 1, P - 1);       Version := Copy(Version, P + 1, Length(Version) - P);     end     else     begin       S := Version;       Version := '';     end;     if S = '' then       Result := -1     else     try       Result := StrToInt(S);     except       Result := -1;     end;   end;  begin   Result := 0;   repeat     N1 := GetNextNumber(AVersion1);     N2 := GetNextNumber(AVersion2);     if N2 > N1 then     begin       Result := 1;       Exit;     end     else     if N2 < N1 then     begin       Result := -1;       Exit;     end   until (AVersion1 = '') and (AVersion2 = ''); end;  function GetFmtFileVersion(const FileName: String = ''; const Fmt: String = '%d.%d.%d.%d'): String; var   sFileName: String;   iBufferSize: DWORD;   iDummy: DWORD;   pBuffer: Pointer;   pFileInfo: Pointer;   iVer: array[1..4] of Word; begin   // set default value   Result := '';   // get filename of exe/dll if no filename is specified   sFileName := FileName;   if (sFileName = '') then   begin     // prepare buffer for path and terminating #0     SetLength(sFileName, MAX_PATH + 1);     SetLength(sFileName,       GetModuleFileName(hInstance, PChar(sFileName), MAX_PATH + 1));   end;   // get size of version info (0 if no version info exists)   iBufferSize := GetFileVersionInfoSize(PChar(sFileName), iDummy);   if (iBufferSize > 0) then   begin     GetMem(pBuffer, iBufferSize);     try     // get fixed file info (language independent)     GetFileVersionInfo(PChar(sFileName), 0, iBufferSize, pBuffer);     VerQueryValue(pBuffer, '\', pFileInfo, iDummy);     // read version blocks     iVer[1] := HiWord(PVSFixedFileInfo(pFileInfo)^.dwFileVersionMS);     iVer[2] := LoWord(PVSFixedFileInfo(pFileInfo)^.dwFileVersionMS);     iVer[3] := HiWord(PVSFixedFileInfo(pFileInfo)^.dwFileVersionLS);     iVer[4] := LoWord(PVSFixedFileInfo(pFileInfo)^.dwFileVersionLS);     finally       FreeMem(pBuffer);     end;     // format result string     Result := Format(Fmt, [iVer[1], iVer[2], iVer[3], iVer[4]]);   end; end;   function KillRunningApp(hInstall: MSIHandle): Integer; stdcall; var   aProcesses: array[0..1023] of DWORD;   cbNeeded: DWORD;   cProcesses: DWORD;   i:    integer;   szProcessName: array[0..MAX_PATH - 1] of char;   hProcess: THandle;   hMod: HModule;   sProcessName : PChar;   iProcessNameLength : Cardinal; begin   iProcessNameLength := MAX_PATH;   sProcessName := StrAlloc(MAX_PATH);    try     //reads the value from 'PROGRAM_TO_KILL' that is stored in the PROPERTY table     MsiGetProperty(hInstall, 'PROGRAM_TO_KILL', sProcessName, iProcessNameLength);      if not EnumProcesses(@aProcesses, sizeof(aProcesses), cbNeeded) then     begin       Exit;     end;     cProcesses := cbNeeded div sizeof(DWORD);      for i := 0 to cProcesses - 1 do     begin       hProcess := OpenProcess(PROCESS_QUERY_INFORMATION or PROCESS_VM_READ or PROCESS_TERMINATE, False, aProcesses[i]);       try       if hProcess <> 0 then       begin         if EnumProcessModules(hProcess, @hMod, sizeof(hMod), cbNeeded) then         begin           GetModuleBaseName(hProcess, hMod, szProcessName, sizeof(szProcessName));           if UpperCase(szProcessName) = UpperCase(sProcessName) then           begin             TerminateProcess(hProcess, 0);           end;         end;       end;       finally         CloseHandle(hProcess);       end;                           end;   finally     StrDispose(sProcessName);   end;    Result:= ERROR_SUCCESS; //return success regardless of actual outcome end;   function CheckIfUpgradeable(hInstall: MSIHandle): Integer; stdcall; var   Current_Notepad_version : PChar;   Current_Notepad_version_Length  : Cardinal;   sWinDir, sProgramFiles : string;   bUpgradeableVersion : boolean;   iNotepad_compare  : integer;   sNotepad_version  : string;   sNotepad_Location  : string;   iResult : Cardinal; begin   bUpgradeableVersion := False;   sWinDir := ExcludeTrailingBackslash(JclSysInfo.GetWindowsFolder);   sProgramFiles := ExcludeTrailingBackslash(JclSysInfo.GetProgramFilesFolder);    Current_Notepad_version_Length := MAX_PATH;   Current_Notepad_version := StrAlloc(MAX_PATH);    sNotepad_Location := sWinDir+'\system32\Notepad.exe';    iResult := ERROR_SUCCESS;    try     //reads the value from 'NOTEPAD_VERSION' that is stored in the PROPERTY table     MsiGetProperty(hInstall, 'NOTEPAD_VERSION', Current_Notepad_version, Current_Notepad_version_Length);      if Not (FileExists(sNotepad_Location)) then     begin       bUpgradeableVersion := True;       LogString(hInstall,'Notepad.exe was not found at: ''+sNotepad_Location+''');       LogString(hInstall,'This version will be upgraded.');       iResult := ERROR_SUCCESS;       Exit;     end;      sNotepad_version := GetFmtFileVersion(sNotepad_Location);     LogString(hInstall,'Found Notepad version=''+sNotepad_version+''');       iNotepad_compare := CompareVersionNumbers(sNotepad_version,StrPas(Current_Notepad_version));      if (iNotepad_compare < 0) then     begin       bUpgradeableVersion := False;     end     else     begin       bUpgradeableVersion := True;     end;       if bUpgradeableVersion then     begin       LogString(hInstall,'This version will be upgraded.');       iResult := ERROR_SUCCESS;     end     else     begin       MsiSetProperty(hInstall,'UPGRADEABLE_VERSION','NO'); //this indicates failure -- this value is read by another custom action executed after this action       LogString(hInstall,'ERROR: A newer version of this software is already installed. Setup cannot continue!');       iResult := ERROR_SUCCESS;     end;   finally     StrDispose(Current_Notepad_version);   end;    Result:= iResult; //this function always returns success, however it could return any of the values listed below // //Custom Action Return Values //================================ // //Return value                        Description // //ERROR_FUNCTION_NOT_CALLED           Action not executed. //ERROR_SUCCESS                       Completed actions successfully. //ERROR_INSTALL_USEREXIT              User terminated prematurely. //ERROR_INSTALL_FAILURE               Unrecoverable error occurred. //ERROR_NO_MORE_ITEMS                 Skip remaining actions, not an error. // end;  exports CheckIfUpgradeable; exports KillRunningApp;  begin end. 

And here is the supporting unit ‘MSILogging.pas’. This unit can be used as-is in other MSI DLL projects.

unit MSILogging;  interface  uses   Windows,   SysUtils,   JwaMsi,   JwaMsiQuery,   JwaMSIDefs;  procedure LogString(hInstall: MSIHandle; sMsgString : string); function MsiMessageBox(hInstall: MSIHandle; sMsgString : string; dwDlgFlags : integer): integer;   implementation  procedure LogString(hInstall: MSIHandle; sMsgString : string); var   hNewMsiHandle : MSIHandle; begin   try     hNewMsiHandle := MsiCreateRecord(2);      sMsgString := '-- MSI_LOGGING -- ' + sMsgString;     MsiRecordSetString(hNewMsiHandle, 0, PChar(sMsgString) );     MsiProcessMessage(hInstall, INSTALLMESSAGE(INSTALLMESSAGE_INFO), hNewMsiHandle);   finally     MsiCloseHandle(hNewMsiHandle);   end; end;   function MsiMessageBox(hInstall: MSIHandle; sMsgString : string; dwDlgFlags : integer): integer; var   hNewMsiHandle : MSIHandle; begin   try     hNewMsiHandle := MsiCreateRecord(2);     MsiRecordSetString(hNewMsiHandle, 0, PChar(sMsgString) );   finally     MsiCloseHandle(hNewMsiHandle);   end;    //Result := (MsiProcessMessage(hInstall, INSTALLMESSAGE(dwDlgFlags), hNewMsiHandle));     Result := (MsiProcessMessage(hInstall, INSTALLMESSAGE(INSTALLMESSAGE_USER + dwDlgFlags), hNewMsiHandle)); end;  end.