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{******************************************************************}
{ }
{ Project JEDI }
{ OS independent Dynamic Loading Helpers }
{ }
{ The initial developer of the this code is }
{ Robert Marquardt <robert_marquardt@gmx.de) }
{ }
{ Copyright (C) 2000, 2001 Robert Marquardt. }
{ }
{ Obtained through: }
{ Joint Endeavour of Delphi Innovators (Project JEDI) }
{ }
{ You may retrieve the latest version of this file at the Project }
{ JEDI home page, located at http://delphi-jedi.org }
{ }
{ The contents of this file are used with permission, subject to }
{ the Mozilla Public License Version 1.1 (the "License"); you may }
{ not use this file except in compliance with the License. You may }
{ obtain a copy of the License at }
{ http://www.mozilla.org/NPL/NPL-1_1Final.html }
{ }
{ Software distributed under the License is distributed on an }
{ "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or }
{ implied. See the License for the specific language governing }
{ rights and limitations under the License. }
{ }
{******************************************************************}
unit ModuleLoader;
interface
{$WEAKPACKAGEUNIT ON}
uses
Libc;
type
// Handle to a loaded .so
TModuleHandle = Pointer;
const
// Value designating an unassigned TModuleHandle od a failed loading
INVALID_MODULEHANDLE_VALUE = TModuleHandle(nil);
function LoadModule(var Module: TModuleHandle; FileName: string): Boolean;
function LoadModuleEx(var Module: TModuleHandle; FileName: string; Flags: Cardinal): Boolean;
procedure UnloadModule(var Module: TModuleHandle);
function GetModuleSymbol(Module: TModuleHandle; SymbolName: string): Pointer;
function GetModuleSymbolEx(Module: TModuleHandle; SymbolName: string; var Accu: Boolean): Pointer;
function ReadModuleData(Module: TModuleHandle; SymbolName: string; var Buffer; Size: Cardinal): Boolean;
function WriteModuleData(Module: TModuleHandle; SymbolName: string; var Buffer; Size: Cardinal): Boolean;
implementation
// load the .so file FileName
// the rules for FileName are those of dlopen()
// Returns: True = success, False = failure to load
// Assigns: the handle of the loaded .so to Module
// Warning: if Module has any other value than INVALID_MODULEHANDLE_VALUE
// on entry the function will do nothing but returning success.
function LoadModule(var Module: TModuleHandle; FileName: string): Boolean;
begin
Module := dlopen(PChar(FileName), RTLD_LAZY);
Result := Module <> INVALID_MODULEHANDLE_VALUE;
end;
// load the .so file FileName
// dlopen() with flags is used to get better control of the loading
// for the allowed values for flags see "man dlopen".
function LoadModuleEx(var Module: TModuleHandle; FileName: string; Flags: Cardinal): Boolean;
begin
Module := dlopen(PChar(FileName), Flags);
Result := Module <> INVALID_MODULEHANDLE_VALUE;
end;
// unload a .so loaded with LoadModule or LoadModuleEx
// The procedure will not try to unload a handle with
// value INVALID_MODULEHANDLE_VALUE and assigns this value
// to Module after unload.
procedure UnloadModule(var Module: TModuleHandle);
begin
if Module <> INVALID_MODULEHANDLE_VALUE then
dlclose(Module);
Module := INVALID_MODULEHANDLE_VALUE;
end;
// returns the pointer to the symbol named SymbolName
// if it is exported from the .so Module
// nil is returned if the symbol is not available
function GetModuleSymbol(Module: TModuleHandle; SymbolName: string): Pointer;
begin
Result := nil;
if Module <> INVALID_MODULEHANDLE_VALUE then
Result := dlsym(Module, PChar(SymbolName));
end;
// returns the pointer to the symbol named SymbolName
// if it is exported from the .so Module
// nil is returned if the symbol is not available.
// as an extra the boolean variable Accu is updated
// by anding in the success of the function.
// This is very handy for rendering a global result
// when accessing a long list of symbols.
function GetModuleSymbolEx(Module: TModuleHandle; SymbolName: string; var Accu: Boolean): Pointer;
begin
Result := nil;
if Module <> INVALID_MODULEHANDLE_VALUE then
Result := dlsym(Module, PChar(SymbolName));
Accu := Accu and (Result <> nil);
end;
// get the value of variables exported from a .so Module
// Delphi cannot access variables in a .so directly, so
// this function allows to copy the data from the .so.
// Beware! You are accessing the .so memory image directly.
// Be sure to access a variable not a function and be sure
// to read the correct amount of data.
function ReadModuleData(Module: TModuleHandle; SymbolName: string; var Buffer; Size: Cardinal): Boolean;
var
Sym: Pointer;
begin
Result := True;
Sym := GetModuleSymbolEx(Module, SymbolName, Result);
if Result then
Move(Sym^, Buffer, Size);
end;
// set the value of variables exported from a .so Module
// Delphi cannot access variables in a .so directly, so
// this function allows to copy the data to the .so!
// BEWARE! You are accessing the .so memory image directly.
// Be sure to access a variable not a function and be sure
// to write the correct amount of data.
// The changes are not persistent. They get lost when the
// .so is unloaded.
function WriteModuleData(Module: TModuleHandle; SymbolName: string; var Buffer; Size: Cardinal): Boolean;
var
Sym: Pointer;
begin
Result := True;
Sym := GetModuleSymbolEx(Module, SymbolName, Result);
if Result then
Move(Buffer, Sym^, Size);
end;
end.
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