The Pascal script can call several built-in support functions.

Support functions

Here's the list of support functions that can be called from within the Pascal script.

Setup or Uninstall Info functions
function GetCmdTail: String;
function ParamCount: Integer;
function ParamStr(Index: Integer): String;

function ActiveLanguage: String;

function CustomMessage(const MsgName: String): String;
function FmtMessage(const S: String; const Args: array of String): String;
function SetupMessage(const ID: TSetupMessageID): String;

function WizardDirValue: String;
function WizardGroupValue: String;
function WizardNoIcons: Boolean;
function WizardSetupType(const Description: Boolean): String;
function WizardSelectedComponents(const Descriptions: Boolean): String;
function WizardSelectedTasks(const Descriptions: Boolean): String;
function WizardSilent: Boolean;

function IsUninstaller: Boolean;
function UninstallSilent: Boolean;

function CurrentFilename: String;
function CurrentSourceFilename: String;

function ExpandConstant(const S: String): String;
function ExpandConstantEx(const S: String; const CustomConst, CustomValue: String): String;

function IsComponentSelected(const Components: String): Boolean;
function IsTaskSelected(const Tasks: String): Boolean;

procedure ExtractTemporaryFile(const FileName: String);
function ExtractTemporaryFiles(const Pattern: String): Integer;

function GetPreviousData(const ValueName, DefaultValueData: String): String;
function SetPreviousData(const PreviousDataKey: Integer; const ValueName, ValueData: String): Boolean;

function Terminated: Boolean;

function RegisterExtraCloseApplicationsResource(const DisableFsRedir: Boolean; const AFilename: String): Boolean;
function RmSessionStarted: Boolean;

Exception functions

procedure Abort;
procedure RaiseException(const Msg: String);

function GetExceptionMessage: String;
procedure ShowExceptionMessage;

System functions

function IsAdminLoggedOn: Boolean;
function IsPowerUserLoggedOn: Boolean;
function GetWindowsVersion: Cardinal;
procedure GetWindowsVersionEx(var Version: TWindowsVersion);
function GetWindowsVersionString: String;

function IsWin64: Boolean;
function Is64BitInstallMode: Boolean;
function ProcessorArchitecture: TSetupProcessorArchitecture;

function InstallOnThisVersion(const MinVersion, OnlyBelowVersion: String): Boolean;

function GetEnv(const EnvVar: String): String;
function GetUserNameString: String;
function GetComputerNameString: String;

function GetUILanguage: Integer;

function FontExists(const FaceName: String): Boolean;

function FindWindowByClassName(const ClassName: String): HWND;
function FindWindowByWindowName(const WindowName: String): HWND;
function SendMessage(const Wnd: HWND; const Msg, WParam, LParam: Longint): Longint;
function PostMessage(const Wnd: HWND; const Msg, WParam, LParam: Longint): Boolean;
function SendNotifyMessage(const Wnd: HWND; const Msg, WParam, LParam: Longint): Boolean;
function RegisterWindowMessage(const Name: String): Longint;
function SendBroadcastMessage(const Msg, WParam, LParam: Longint): Longint;
function PostBroadcastMessage(const Msg, WParam, LParam: Longint): Boolean;
function SendBroadcastNotifyMessage(const Msg, WParam, LParam: Longint): Boolean;

procedure CreateMutex(const Name: String);
function CheckForMutexes(Mutexes: String): Boolean;

procedure MakePendingFileRenameOperationsChecksum: String;

procedure UnloadDLL(Filename: String);
function DLLGetLastError(): Longint;

String functions

function Chr(B: Byte): Char;
function Ord(C: Char): Byte;
function Copy(S: String; Index, Count: Integer): String;
function Length(s: String): Longint;
function Lowercase(S: String): String;
function Uppercase(S: String): String;
function AnsiLowercase(S: String): String;
function AnsiUppercase(S: String): String;
function StringOfChar(c: Char; I : Longint): String;
procedure Delete(var S: String; Index, Count: Integer);
procedure Insert(Source: String; var Dest: String; Index: Integer);
function StringChange(var S: String; const FromStr, ToStr: String): Integer;
function StringChangeEx(var S: String; const FromStr, ToStr: String; const SupportDBCS: Boolean): Integer;
function Pos(SubStr, S: String): Integer;
function AddQuotes(const S: String): String;
function RemoveQuotes(const S: String): String;
function ConvertPercentStr(var S: String): Boolean;

function CompareText(const S1, S2: string): Integer;
function CompareStr(const S1, S2: string): Integer;

function Format(const Format: string; const Args: array of const): string;

function Trim(const S: string): String;
function TrimLeft(const S: string): String;
function TrimRight(const S: string): String;

function StrToIntDef(s: string; def: Longint): Longint;
function StrToInt(s: string): Longint;
function StrToInt64Def(s: string; def: Int64): Int64;
function StrToInt64(s: string): Int64;
function StrToFloat(s: string): Extended;
function IntToStr(i: Int64): String;
function FloatToStr(e: extended): String;

function CharLength(const S: String; const Index: Integer): Integer;

function AddBackslash(const S: String): String;
function RemoveBackslashUnlessRoot(const S: String): String;
function RemoveBackslash(const S: String): String;
function AddPeriod(const S: String): String;
function ChangeFileExt(const FileName, Extension: string): String;
function ExtractFileExt(const FileName: string): String;
function ExtractFileDir(const FileName: string): String;
function ExtractFilePath(const FileName: string): String;
function ExtractFileName(const FileName: string): String;
function ExtractFileDrive(const FileName: string): String;
function ExtractRelativePath(const BaseName, DestName: String): String;
function ExpandFileName(const FileName: string): String;
function ExpandUNCFileName(const FileName: string): String;

function GetDateTimeString(const DateTimeFormat: String; const DateSeparator, TimeSeparator: Char): String;

procedure SetLength(var S: String; L: Longint);
procedure CharToOemBuff(var S: AnsiString);
procedure OemToCharBuff(var S: AnsiString);

function GetMD5OfString(const S: AnsiString): String;
function GetMD5OfUnicodeString(const S: String): String;
function GetSHA1OfString(const S: AnsiString): String;
function GetSHA1OfUnicodeString(const S: String): String;

function SysErrorMessage(ErrorCode: Integer): String;

function MinimizePathName(const Filename: String; const Font: TFont; MaxLen: Integer): String;

Array functions

function GetArrayLength(var Arr: Array): Longint;
procedure SetArrayLength(var Arr: Array; I: Longint);

Variant functions

function Null: Variant;
function Unassigned: Variant;

function VarIsEmpty(const V: Variant): Boolean;
function VarIsClear(const V: Variant): Boolean;
function VarIsNull(const V: Variant): Boolean;
function VarType(const V: Variant): TVarType;

File System functions

function DirExists(const Name: String): Boolean;
function FileExists(const Name: String): Boolean;
function FileOrDirExists(const Name: String): Boolean;
function FileSize(const Name: String; var Size: Integer): Boolean;
function GetSpaceOnDisk(const Path: String; const InMegabytes: Boolean; var Free, Total: Cardinal): Boolean;
function GetSpaceOnDisk64(const Path: String; var Free, Total: Int64): Boolean;

function FileSearch(const Name, DirList: string): String;
function FindFirst(const FileName: String; var FindRec: TFindRec): Boolean;
function FindNext(var FindRec: TFindRec): Boolean;
procedure FindClose(var FindRec: TFindRec);

function GetCurrentDir: String;
function SetCurrentDir(const Dir: string): Boolean;
function GetWinDir: String;
function GetSystemDir: String;
function GetSysWow64Dir: String;
function GetTempDir: String;
function GetShellFolder(Common: Boolean; const ID: TShellFolderID): String;
function GetShellFolderByCSIDL(const Folder: Integer; const Create: Boolean): String;

function GetShortName(const LongName: String): String;
function GenerateUniqueName(Path: String; const Extension: String): String;

function GetVersionNumbers(const Filename: String; var VersionMS, VersionLS: Cardinal): Boolean;
function GetVersionNumbersString(const Filename: String; var Version: String): Boolean;

function IsProtectedSystemFile(const Filename: String): Boolean;

function GetMD5OfFile(const Filename: String): String;
function GetSHA1OfFile(const Filename: String): String;

function EnableFsRedirection(const Enable: Boolean): Boolean;

File functions

function Exec(const Filename, Params, WorkingDir: String; const ShowCmd: Integer; const Wait: TExecWait; var ResultCode: Integer): Boolean;
function ExecAsOriginalUser(const Filename, Params, WorkingDir: String; const ShowCmd: Integer; const Wait: TExecWait; var ResultCode: Integer): Boolean;
function ShellExec(const Verb, Filename, Params, WorkingDir: String; const ShowCmd: Integer; const Wait: TExecWait; var ErrorCode: Integer): Boolean;
function ShellExecAsOriginalUser(const Verb, Filename, Params, WorkingDir: String; const ShowCmd: Integer; const Wait: TExecWait; var ErrorCode: Integer): Boolean;

function RenameFile(const OldName, NewName: string): Boolean;
function FileCopy(const ExistingFile, NewFile: String; const FailIfExists: Boolean): Boolean;
function DeleteFile(const FileName: string): Boolean;
procedure DelayDeleteFile(const Filename: String; const Tries: Integer);
function SetNTFSCompression(const FileOrDir: String; Compress: Boolean): Boolean;

function LoadStringFromFile(const FileName: String; var S: AnsiString): Boolean;
function LoadStringsFromFile(const FileName: String; var S: TArrayOfString): Boolean;
function SaveStringToFile(const FileName: String; const S: AnsiString; const Append: Boolean): Boolean;
function SaveStringsToFile(const FileName: String; const S: TArrayOfString; const Append: Boolean): Boolean;
function SaveStringsToUTF8File(const FileName: String; const S: TArrayOfString; const Append: Boolean): Boolean;

function CreateDir(const Dir: string): Boolean;
function ForceDirectories(Dir: string): Boolean;
function RemoveDir(const Dir: string): Boolean;
function DelTree(const Path: String; const IsDir, DeleteFiles, DeleteSubdirsAlso: Boolean): Boolean;

function CreateShellLink(const Filename, Description, ShortcutTo, Parameters, WorkingDir, IconFilename: String; const IconIndex, ShowCmd: Integer): String;
function UnpinShellLink(const Filename: String): Boolean;

procedure RegisterServer(const Is64Bit: Boolean; const Filename: String; const FailCriticalErrors: Boolean);
function UnregisterServer(const Is64Bit: Boolean; const Filename: String; const FailCriticalErrors: Boolean): Boolean;
procedure RegisterTypeLibrary(const Is64Bit: Boolean; const Filename: String);
function UnregisterTypeLibrary(const Is64Bit: Boolean; const Filename: String): Boolean
procedure IncrementSharedCount(const Is64Bit: Boolean; const Filename: String; const AlreadyExisted: Boolean);
function DecrementSharedCount(const Is64Bit: Boolean; const Filename: String): Boolean;
procedure RestartReplace(const TempFile, DestFile: String);
procedure UnregisterFont(const FontName, FontFilename: String);
function ModifyPifFile(const Filename: String; const CloseOnExit: Boolean): Boolean;

Registry functions

function RegKeyExists(const RootKey: Integer; const SubKeyName: String): Boolean;
function RegValueExists(const RootKey: Integer; const SubKeyName, ValueName: String): Boolean;

function RegGetSubkeyNames(const RootKey: Integer; const SubKeyName: String; var Names: TArrayOfString): Boolean;
function RegGetValueNames(const RootKey: Integer; const SubKeyName: String; var Names: TArrayOfString): Boolean;

function RegQueryStringValue(const RootKey: Integer; const SubKeyName, ValueName: String; var ResultStr: String): Boolean;
function RegQueryMultiStringValue(const RootKey: Integer; const SubKeyName, ValueName: String; var ResultStr: String): Boolean;
function RegQueryDWordValue(const RootKey: Integer; const SubKeyName, ValueName: String; var ResultDWord: Cardinal): Boolean;
function RegQueryBinaryValue(const RootKey: Integer; const SubKeyName, ValueName: String; var ResultStr: AnsiString): Boolean;

function RegWriteStringValue(const RootKey: Integer; const SubKeyName, ValueName, Data: String): Boolean;
function RegWriteExpandStringValue(const RootKey: Integer; const SubKeyName, ValueName, Data: String): Boolean;
function RegWriteMultiStringValue(const RootKey: Integer; const SubKeyName, ValueName, Data: String): Boolean;
function RegWriteDWordValue(const RootKey: Integer; const SubKeyName, ValueName: String; const Data: Cardinal): Boolean;
function RegWriteBinaryValue(const RootKey: Integer; const SubKeyName, ValueName: String; const Data: AnsiString): Boolean;

function RegDeleteKeyIncludingSubkeys(const RootKey: Integer; const SubkeyName: String): Boolean;
function RegDeleteKeyIfEmpty(const RootKey: Integer; const SubkeyName: String): Boolean;
function RegDeleteValue(const RootKey: Integer; const SubKeyName, ValueName: String): Boolean;

INI File functions

function IniKeyExists(const Section, Key, Filename: String): Boolean;
function IsIniSectionEmpty(const Section, Filename: String): Boolean;

function GetIniBool(const Section, Key: String; const Default: Boolean; const Filename: String): Boolean
function GetIniInt(const Section, Key: String; const Default, Min, Max: Longint; const Filename: String): Longint;
function GetIniString(const Section, Key, Default, Filename: String): String;

function SetIniBool(const Section, Key: String; const Value: Boolean; const Filename: String): Boolean;
function SetIniInt(const Section, Key: String; const Value: Longint; const Filename: String): Boolean;
function SetIniString(const Section, Key, Value, Filename: String): Boolean;

procedure DeleteIniSection(const Section, Filename: String);
procedure DeleteIniEntry(const Section, Key, Filename: String);

Custom Setup Wizard Page functions

function CreateInputQueryPage(const AfterID: Integer; const ACaption, ADescription, ASubCaption: String): TInputQueryWizardPage;
function CreateInputOptionPage(const AfterID: Integer; const ACaption, ADescription, ASubCaption: String; Exclusive, ListBox: Boolean): TInputOptionWizardPage;
function CreateInputDirPage(const AfterID: Integer; const ACaption, ADescription, ASubCaption: String; AAppendDir: Boolean; ANewFolderName: String): TInputDirWizardPage;
function CreateInputFilePage(const AfterID: Integer; const ACaption, ADescription, ASubCaption: String): TInputFileWizardPage;
function CreateOutputMsgPage(const AfterID: Integer; const ACaption, ADescription, AMsg: String): TOutputMsgWizardPage;
function CreateOutputMsgMemoPage(const AfterID: Integer; const ACaption, ADescription, ASubCaption: String; const AMsg: AnsiString): TOutputMsgMemoWizardPage;
function CreateOutputProgressPage(const ACaption, ADescription: String): TOutputProgressWizardPage;
function CreateCustomPage(const AfterID: Integer; const ACaption, ADescription: String): TWizardPage;

function CreateCustomForm: TSetupForm;

function PageFromID(const ID: Integer): TWizardPage;
function PageIndexFromID(const ID: Integer): Integer;
function ScaleX(X: Integer): Integer;
function ScaleY(Y: Integer): Integer;

Dialog functions

function MsgBox(const Text: String; const Typ: TMsgBoxType; const Buttons: Integer): Integer;
function SuppressibleMsgBox(const Text: String; const Typ: TMsgBoxType; const Buttons, Default: Integer): Integer;
function GetOpenFileName(const Prompt: String; var FileName: String; const InitialDirectory, Filter, DefaultExtension: String): Boolean;
function GetSaveFileName(const Prompt: String; var FileName: String; const InitialDirectory, Filter, DefaultExtension: String): Boolean;
function BrowseForFolder(const Prompt: String; var Directory: String; const NewFolderButton: Boolean): Boolean;
function ExitSetupMsgBox: Boolean;

COM Automation objects support functions

function CreateOleObject(const ClassName: string): Variant;
function GetActiveOleObject(const ClassName: string): Variant;
function IDispatchInvoke(Self: IDispatch; PropertySet: Boolean; const Name: String; Par: array of Variant): Variant;
function CreateComObject(const ClassID: TGUID): IUnknown;
function StringToGUID(const S: String): TGUID;
procedure OleCheck(Result: HResult);
procedure CoFreeUnusedLibraries;

Setup Logging functions

procedure Log(const S: String);

Other functions

procedure Sleep(const Milliseconds: LongInt);
function Random(const Range: Integer): Integer;
procedure Beep;

procedure BringToFrontAndRestore;

Deprecated functions

function LoadDLL(const DLLName: String; var ErrorCode: Integer): Longint;
function CallDLLProc(const DLLHandle: Longint; const ProcName: String; const Param1, Param2: Longint; var Result: Longint): Boolean;
function FreeDLL(const DLLHandle: Longint): Boolean;

function CastStringToInteger(var S: String): Longint;
function CastIntegerToString(const L: Longint): String;

Constants

Here's the list of constants used by these functions:

CurStep values
ssInstall, ssPostInstall, ssDone

CurPage values
wpWelcome, wpLicense, wpPassword, wpInfoBefore, wpUserInfo, wpSelectDir, wpSelectComponents, wpSelectProgramGroup, wpSelectTasks, wpReady, wpPreparing, wpInstalling, wpInfoAfter, wpFinished

TMsgBoxType
mbInformation, mbConfirmation, mbError, mbCriticalError

MsgBox - Buttons flags
MB_OK, MB_OKCANCEL, MB_ABORTRETRYIGNORE, MB_YESNOCANCEL, MB_YESNO, MB_RETRYCANCEL, MB_DEFBUTTON1, MB_DEFBUTTON2, MB_DEFBUTTON3, MB_SETFOREGROUND

MsgBox - return values
IDOK, IDCANCEL, IDABORT, IDRETRY, IDIGNORE, IDYES, IDNO

TShellFolderID
sfDesktop, sfStartMenu, sfPrograms, sfStartup, sfSendTo, sfFonts, sfAppData, sfDocs, sfTemplates, sfFavorites, sfLocalAppData

Reg* - RootKey values (also see the [Registry] section documentation)
HKEY_CLASSES_ROOT, HKEY_CLASSES_ROOT_32, HKEY_CLASSES_ROOT_64,
HKEY_CURRENT_USER, HKEY_CURRENT_USER_32, HKEY_CURRENT_USER_64,
HKEY_LOCAL_MACHINE, HKEY_LOCAL_MACHINE_32, HKEY_LOCAL_MACHINE_64,
HKEY_USERS, HKEY_USERS_32, HKEY_USERS_64,
HKEY_PERFORMANCE_DATA,
HKEY_CURRENT_CONFIG, HKEY_CURRENT_CONFIG_32, HKEY_CURRENT_CONFIG_64,
HKEY_DYN_DATA,
HKCR, HKCR32, HKCR64, HKCU, HKCU32, HKCU64, HKLM, HKLM32, HKLM64, HKU, HKU32, HKU64, HKCC, HKCC32, HKCC64

TShouldProcessEntryResult
srNo, srYes, srUnknown

TSetupMessageID
Use 'msg' + the message name. Example: SetupMessage(msgSetupAppTitle)

Exec and ShellExec - ShowCmd values
SW_SHOW, SW_SHOWNORMAL, SW_SHOWMAXIMIZED, SW_SHOWMINIMIZED, SW_SHOWMINNOACTIVE, SW_HIDE