IFPSTools.NET

Successor to IFPSTools; for working with RemObject PascalScript compiled bytecode files.

Written in C#, libraries target .NET Standard 2.0 and console applications target .NET Framework.

Contains the following:

IFPSLib

Library for reading, modifying, creating, writing and disassembling compiled IFPS scripts. Saving a loaded script without modification is expected to output an identical binary, not doing so is considered a bug.

The API is modeled on dnlib's.

A known bug is that the Extended primitive in IFPSLib will always refer internally to an 80-bit floating point value; any compiled IFPS script intended for an architecture that is not x86 (32-bit) will use 64-bit floating point values.

IFPSAsmLib

Library implementing an assembler for IFPS scripts.

Depends on IFPSLib.

Assembling the output of IFPSLib's disassembler is expected to output an identical binary, not doing so is considered a bug.

ifpsdasm

Wrapper around IFPSLib's disassember functionality.

Usage: ifpsdasm CompiledCode.bin will disassemble CompiledCode.bin into CompiledCode.txt.

ifpsasm

Wrapper around IFPSAsmLib.

Usage: ifpsasm file.txt will assemble file.txt into file.bin

uninno

The Inno Setup Uninstaller Configuration Creator.

This tool creates an Inno Setup uninstaller *.dat file (ie, unins000.dat) from a compiled IFPS script.

This allows the usage of the Inno Setup uninstaller as a lolbin; most systems would have several versions already on the system, and signed samples can be found quite easily (even MS signed a few: Skype, VSCode, Azure Storage Explorer...)

See uninno --help for usage instructions.

innounp does not extract the uninstaller, but for a signed sample, the uninstaller equals the setup core executable; so the uninstaller can be dumped by running an Inno Setup installer under a debugger and setting a breakpoint on CreateProcessW, then copying it out of %TEMP%.

After dumping an uninstaller, the required version number can be obtained by getting xref to the string "Install was done in 64-bit mode but not running 64-bit Windows now"; further up should be mov ecx, <version constant> ; mov dx, 0x20 or similar.

Bit 31 means Unicode; 0x86000500 means 6.0.5u; 0x06000500 means 6.0.5.

Differences from earlier IFPSTools

Compared to the earlier IFPSTools, IFPSTools.NET implements file saving, modifying, assembling...

The disassembler also includes additional functionality that was not implemented in the earlier IFPSTools, for example COM vtable functions and function/type attributes all disassemble correctly.

IFPS assembly format

Quoted string literals are similar to C# regular string literals, except \U is not allowed, and \x specifies exactly one byte (two nibbles).

Declarations:

• .version <int32> - script file version. If not present, will be set to VERSION_HIGHEST (23) by default.
• .entry <funcname> - specifies the entry point of the script, which must have the declaration .function(export) void name().
• .type <declaration> <name> - declares a named type (which can be exported if .type(export) is used), of which the following are allowed:
  • primitive(<prim>) - primitive type, of which prim can be U8 (unsigned 8-bit integer), S8 (signed 8-bit integer) , U16 (unsigned 16-bit integer), S16 (signed 16-bit integer), U32 (unsigned 32-bit integer), S32 (signed 32-bit integer), S64 (signed 64-bit integer), Single (32-bit float), Double (64-bit float), Currency (OLE Automation tagCY), Extended (80-bit float), String (ASCII string), Pointer, PChar , Variant (OLE Automation VARIANT), Char (ASCII character), UnicodeString, WideString (same as UnicodeString), or WideChar (UTF-16 character).
  • array(<type>) - variable length array, where type is the name of a previously declared type.
  • array(<type>,<length>,<startindex>) - static array, where type is the name of a previously declared type; length is the number of elements in the array; and startindex is the base index of the array.
  • class(<internalname>) - an internally-defined class, where internalname is the internal name of that class (for example class(TMainForm)).
  • interface("guidstring") - a COM interface, of a GUID that is specified as a string; example: interface("00000000-0000-0000-C000-000000000046") is IUnknown.
  • funcptr(<declaration>) - a function pointer, where declaration is an external function declaration: void|returnsval (__in|__out,...)
  • record(...) - a record (ie, structure), where the body is the list of element types which must be previously-defined: for example record(U8,U8,U16) would be the equivalent of struct { U8; U8; U16; }. Elements have no name and are accessed by their element index.
  • set(<bitsize>) - a set (ie, bit array), of bitsize bits in length.
• .global <type> <name> - declares a global variable, which can be exported if .global(export) is used, of a previously declared type and specified name.
• .function(export) external <externaltype> void|returnsval name(externalargs...) - declares an external function, which in practise must always be exported. External functions do not store argument types, as such an external argument must be declared in the form __in|__out|__val|__ref __unknown (__ref is equivalent to __out and __val is equivalent to __in). The following types of external functions are allowed:
  • com(<vtableindex>) callingconvention - a COM vtable function, where vtableindex is the vtable index (not offset) of the function to call, for example com(1) __stdcall would refer to IUnknown::AddRef.
  • class(<classname>, <funcname>) callingconvention - an internally implemented class function or property, for example class(Class, CastToType) __pascal or class(TControl, Left, property) __pascal.
  • dll("dllname", "procname") callingconvention - an exported function from a DLL, for example dll("kernelbase.dll", "ExitProcess") __stdcall. Additional delayload and alteredsearchpath arguments are also supported.
  • internal - an internally implemented function, for example MsgBox() in Inno Setup.
  • The allowed calling conventions are __stdcall, __cdecl, __pascal and __fastcall.
• .function(export) void|<type> name(...) - declares a function implemented as PascalScript bytecode, which must be followed by at least one instruction. The specified return type must have been previously declared. Parameters are specified as __in|__out|__val|__ref type name, for example __in TControl Arg1. (__ref is equivalent to __out and __val is equivalent to __in)
• .alias <name> <varname> - must be specified as part of a PascalScript bytecode function. Declares an alias of a variable name, valid until the end of the function. Local variables are normally numbered as Var1 (etc); declaring an alias allows a local variable to be given a name.
• .define <immediate> <name> - defines a name to any immediate operand to be used in any instruction. Example: .define U32(0xC0000001) STATUS_UNSUCCESSFUL.

Attributes in the form of [attribute(...)] are allowed to be specified before functions and types. They only have meaning to the host application; Inno Setup uses exactly one attribute - functions can have an event(UnicodeString) attribute, see the documentation. An example of that would be: [event(UnicodeString("InitializeUninstall"))].

Labels are allowed as part of a PascalScript bytecode function, in the form of label:. Labels only exist for a single function, and can be used as an operand in branch instructions. A label can not have the name null.

Instruction operands have several forms:

• Operands that refer to an instruction do so via a label. For the starteh instruction, null is allowed to specify an empty operand.
• Operands that refer to a type (like in the pushtype instruction) do so via the type name.
• Operands that refer to a function (like the call instruction) do so via the function name.
• Operands that refer to a variable only (the obsolete setstacktype instruction) do so via the variable name.
• Other operands can refer to a variable (via its name), a constant (via the syntax type(value); function pointers use the function name, strings use quoted literals); or an array or record variable indexed by integer constant (RecordOrArrayVar[0]) or by variable name (RecordOrArrayVar[IndexVar]).

Examples

The examples directory contains a few example scripts, intended to be used with uninno:

• HelloWorld.asm is a simple hello world example.
• HelloWorldWithAttribute.asm demonstrates an initialisation function using an Event attribute.
• DllImportExample.asm demonstrates importing a function from a DLL.

IFPS runtime considerations

It is possible to assemble or save a script which would be considered invalid by the runtime.

Notably, even if it is not used by your script, a compiled script without the primitive(Pointer) type included is invalid; the runtime expects it to be present and calling any function in a script without such a type present leads to a null pointer dereference.