From ecde167da74c86bc047aaf84c5e548cf65a5da98 Mon Sep 17 00:00:00 2001
From: Tomas Bzatek <tbzatek@users.sourceforge.net>
Date: Sat, 7 Jun 2008 20:34:49 +0200
Subject: Initial commit

---
 vfs/ModuleLoader.pas | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 156 insertions(+)
 create mode 100644 vfs/ModuleLoader.pas

(limited to 'vfs/ModuleLoader.pas')

diff --git a/vfs/ModuleLoader.pas b/vfs/ModuleLoader.pas
new file mode 100644
index 0000000..51351dd
--- /dev/null
+++ b/vfs/ModuleLoader.pas
@@ -0,0 +1,156 @@
+{******************************************************************}
+{                                                                  }
+{       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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