How do I determine if a unit has been compiled into a Delphi program?

Question

I want to be able to determine if a particular unit has been compiled into a Delphi program, e.g. the unit SomeUnitName is part of some of my programs but not of others. I w

Answer 1

This function will return the list of unit names included in an application. Works in Delphi 2010. Not verified for other compilers.

function UnitNames: TStrings;
var
  Lib: PLibModule;
  DeDupedLibs: TList<cardinal>;
  TypeInfo: PPackageTypeInfo;
  PInfo: GetPackageInfoTable;
  LibInst: Cardinal;
  u: Integer;
  s: string;
  s8: UTF8String;
  len: Integer;
  P: PByte;
begin
result := TStringList.Create;
DeDupedLibs := TList<cardinal>.Create;
Lib := LibModuleList;
try
  while assigned( Lib) do
    begin
    LibInst := Lib^.Instance;
    Typeinfo := Lib^.TypeInfo;
    if not assigned( TypeInfo) then
      begin
      PInfo := GetProcAddress( LibInst, '@GetPackageInfoTable');
      if assigned( PInfo) then
        TypeInfo := @PInfo^.TypeInfo;
      end;
    if (not assigned( TypeInfo)) or (DeDupedLibs.IndexOf( LibInst) <> -1) then continue;
    DeDupedLibs.Add( LibInst);
    P := Pointer( TypeInfo^.UnitNames);
    for u := 0 to TypeInfo^.UnitCount - 1 do
      begin
      len := P^;
      SetLength( s8, len);
      if len = 0 then Break;
      Inc( P, 1);
      Move( P^, s8[1], len);
      Inc( P, len);
      s := UTF8ToString( s8);
      if Result.IndexOf( s) = -1 then
        Result.Add( s)
      end
    end
finally
  DeDupedLibs.Free
  end
end;

Example to use in the was suggested in the question...

function IsSomeUnitNameInProgram: boolean;
var
  UnitNamesStrs: TStrings;
begin
UnitNamesStrs := UnitNames;
result := UnitNamesStrs.IndexOf('MyUnitName') <> -1;
UnitNamesStrs.Free
end;

Answer 2

Unit names are compiled into the 'PACKAGEINFO' resource where you can look it up:

uses
  SysUtils;

type
  PUnitInfo = ^TUnitInfo;
  TUnitInfo = record
    UnitName: string;
    Found: PBoolean;
  end;

procedure HasUnitProc(const Name: string; NameType: TNameType; Flags: Byte; Param: Pointer);
begin
  case NameType of
    ntContainsUnit:
      with PUnitInfo(Param)^ do
        if SameText(Name, UnitName) then
          Found^ := True;
  end;
end;

function IsUnitCompiledIn(Module: HMODULE; const UnitName: string): Boolean;
var
  Info: TUnitInfo;
  Flags: Integer;
begin
  Result := False;
  Info.UnitName := UnitName;
  Info.Found := @Result;
  GetPackageInfo(Module, @Info, Flags, HasUnitProc);
end;

To do this for the current executable pass it HInstance:

HasActiveX := IsUnitCompiledIn(HInstance, 'ActiveX');

(GetPackageInfo enumerates all units which may be inefficient for executables with many units, in that case you can dissect the implementation in SysUtils and write your own version which stops enumerating when the unit is found.)