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* added some highlevel helper functions to load/unload dynamic libraries.
* initialize/release calls are refcounted. On loading, requested symbols are checked. git-svn-id: trunk@13975 -
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@ -20,6 +20,9 @@ unit dynlibs;
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interface
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uses
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SysUtils, RtlConsts, SysConst;
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{ ---------------------------------------------------------------------
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Read OS-dependent interface declarations.
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---------------------------------------------------------------------}
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@ -38,13 +41,68 @@ Function LoadLibrary(Name : AnsiString) : TLibHandle;
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Function GetProcedureAddress(Lib : TlibHandle; ProcName : AnsiString) : Pointer;
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Function UnloadLibrary(Lib : TLibHandle) : Boolean;
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// Kylix/Delphi compability
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Type
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HModule = TLibHandle;
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Function FreeLibrary(Lib : TLibHandle) : Boolean;
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Function GetProcAddress(Lib : TlibHandle; ProcName : AnsiString) : Pointer;
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// Dynamic Library Manager
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{ Note: If you look for some code that uses this library handler, take a look at
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sqlite3.inc of sqlite package (simple) or
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mysql.inc of mysql package (advanced)
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}
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Type
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HModule = TLibHandle;
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PLibHandler = ^TLibHandler;
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TLibEventLoading = function(User: Pointer; Handler: PLibHandler; out ErrorMsg: String): Boolean;
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TLibEventUnloading = procedure(User: Pointer; Handler: PLibHandler);
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PPLibSymbol = ^PLibSymbol;
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PLibSymbol = ^TLibSymbol;
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TLibSymbol = record
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pvar: PPointer; { pointer to Symbol variable }
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name: String; { name of the Symbol }
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weak: Boolean; { weak }
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end;
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TLibHandler = record
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AbstractName : String;
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Handle : TLibHandle;
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Filename : String;
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Loading : TLibEventLoading;
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Unloading : TLibEventUnloading;
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SymCount : Integer;
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Symbols : PLibSymbol;
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ErrorMsg : String;
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RefCount : Integer;
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end;
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function LibraryHandler(const AbstractName: String; const Symbols: PLibSymbol; const SymCount: Integer;
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const AfterLoading: TLibEventLoading = nil; const BeforeUnloading: TLibEventUnloading = nil): TLibHandler;
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function TryInitializeLibrary(var Handler: TLibHandler; const Filenames: array of String;
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const User: Pointer = nil; const Weak: Boolean = False): Integer;
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function TryInitializeLibrary(var Handler: TLibHandler; const Filename: String;
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const User: Pointer = nil; const Weak: Boolean = False): Integer;
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function InitializeLibrary(var Handler: TLibHandler; const Filenames: array of String;
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const User: Pointer = nil; const Weak: Boolean = False): Integer;
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function InitializeLibrary(var Handler: TLibHandler; const Filename: String;
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const User: Pointer = nil; const Weak: Boolean = False): Integer;
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function ReleaseLibrary(var Handler: TLibHandler; User: Pointer = nil): Integer;
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function GetLastLibraryError(var Handler: TLibHandler): String;
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procedure RaiseLibraryException(var Handler: TLibHandler);
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function LoadLibrarySymbols(const Lib: TLibHandle; const Symbols: PLibSymbol; const Count: Integer;
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const ErrorSym: PPLibSymbol = nil): Boolean;
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procedure ClearLibrarySymbols(const Lib: TLibHandle; const Symbols: PLibSymbol; const Count: Integer);
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// these are for easier crossplatform construction of dll names in dynloading libs.
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Const
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@ -57,11 +115,11 @@ Const
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{$ifdef OS2}
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SharedSuffix = 'dll';
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{$else}
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SharedSuffix = 'so';
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SharedSuffix = 'so';
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{$endif}
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{$endif}
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{$endif}
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{$endif}
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Implementation
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{ ---------------------------------------------------------------------
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@ -88,7 +146,6 @@ Function SafeLoadLibrary(Name : AnsiString) : TLibHandle;
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var w : word;
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{$endif}
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Begin
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{$ifdef i386}
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w:=get8087cw;
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@ -100,4 +157,171 @@ Begin
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{$endif}
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End;
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function LibraryHandler(const AbstractName: String; const Symbols: PLibSymbol; const SymCount: Integer;
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const AfterLoading: TLibEventLoading; const BeforeUnloading: TLibEventUnloading): TLibHandler;
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begin
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Result.AbstractName := AbstractName;
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Result.Handle := NilHandle;
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Result.Filename := '';
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Result.Loading := AfterLoading;
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Result.Unloading := BeforeUnloading;
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Result.SymCount := SymCount;
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Result.Symbols := Symbols;
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Result.ErrorMsg := '';
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Result.RefCount := 0;
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end;
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function TryInitializeLibrary(var Handler: TLibHandler; const Filenames: array of String;
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const User: Pointer; const Weak: Boolean): Integer;
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var
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I: Integer;
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begin
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if Length(Filenames) <= 0 then
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begin
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Handler.ErrorMsg := SVarInvalid;
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Result := -1;
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Exit;
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end;
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for I := 0 to High(Filenames) do
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begin
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Result := TryInitializeLibrary(Handler, Filenames[I], User, Weak);
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if Result > 0 then
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Exit;
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end;
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end;
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function TryInitializeLibrary(var Handler: TLibHandler; const Filename: String;
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const User: Pointer; const Weak: Boolean): Integer;
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var
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ErrSym: PLibSymbol;
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begin
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Handler.ErrorMsg := '';
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if (Handler.Filename <> '') and (Handler.Filename <> Filename) then
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begin
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Handler.ErrorMsg := Format(SLibraryAlreadyLoaded, [Handler.AbstractName, Handler.Filename]);
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Result := -1;
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Exit;
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end;
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Result := InterlockedIncrement(Handler.RefCount);
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if Result = 1 then
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begin
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Handler.Handle := LoadLibrary(Filename);
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if Handler.Handle = NilHandle then
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begin
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Handler.ErrorMsg := Format(SLibraryNotLoaded, [Handler.AbstractName, Filename]);
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Handler.RefCount := 0;
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Result := -1;
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Exit;
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end;
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Handler.Filename := Filename;
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if not LoadLibrarySymbols(Handler.Handle, Handler.Symbols, Handler.SymCount, @ErrSym) and not Weak then
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begin
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UnloadLibrary(Handler.Handle);
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Handler.Handle := NilHandle;
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Handler.Filename := '';
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Handler.ErrorMsg := Format(SLibraryUnknownSym, [ErrSym^.name, Handler.AbstractName, Filename]);
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Handler.RefCount := 0;
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Result := -1;
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Exit;
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end;
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if Assigned(Handler.Loading) and not Handler.Loading(User, @Handler, Handler.ErrorMsg) then
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begin
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UnloadLibrary(Handler.Handle);
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Handler.Handle := NilHandle;
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Handler.Filename := '';
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Handler.RefCount := 0;
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Result := -1;
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Exit;
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end else
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Handler.ErrorMsg := '';
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end;
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end;
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function InitializeLibrary(var Handler: TLibHandler; const Filenames: array of String;
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const User: Pointer; const Weak: Boolean): Integer;
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begin
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Result := TryInitializeLibrary(Handler, Filenames, User, Weak);
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RaiseLibraryException(Handler);
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end;
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function InitializeLibrary(var Handler: TLibHandler; const Filename: String;
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const User: Pointer; const Weak: Boolean): Integer;
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begin
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Result := TryInitializeLibrary(Handler, Filename, User, Weak);
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RaiseLibraryException(Handler);
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end;
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function ReleaseLibrary(var Handler: TLibHandler; User: Pointer): Integer;
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begin
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Handler.ErrorMsg := '';
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Result := InterlockedDecrement(Handler.RefCount);
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if Result = 0 then
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begin
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if Assigned(Handler.Unloading) then
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Handler.Unloading(User, @Handler);
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UnloadLibrary(Handler.Handle);
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Handler.Handle := NilHandle;
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Handler.Filename := '';
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end else
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if Result < 0 then
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Handler.RefCount := 0;
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end;
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function GetLastLibraryError(var Handler: TLibHandler): String;
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begin
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Result := Handler.ErrorMsg;
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Handler.ErrorMsg := '';
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end;
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procedure RaiseLibraryException(var Handler: TLibHandler);
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var
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Msg: String;
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begin
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Msg := GetLastLibraryError(Handler);
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if Msg <> '' then
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raise EInOutError.Create(Msg);
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end;
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function LoadLibrarySymbols(const Lib: TLibHandle; const Symbols: PLibSymbol; const Count: Integer;
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const ErrorSym: PPLibSymbol): Boolean;
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var
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P,L: PLibSymbol;
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begin
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P := Symbols;
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L := @Symbols[Count];
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while P < L do
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begin
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P^.pvar^ := GetProcedureAddress(Lib, P^.name);
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if not Assigned(P^.pvar^) and not P^.weak then
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begin
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if Assigned(ErrorSym) then
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ErrorSym^ := P;
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Result := False;
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Exit;
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end;
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Inc(P);
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end;
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Result := True;
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end;
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procedure ClearLibrarySymbols(const Lib: TLibHandle; const Symbols: PLibSymbol; const Count: Integer);
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var
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P,L: PLibSymbol;
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begin
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P := Symbols;
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L := @Symbols[Count];
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while P < L do
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begin
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P^.pvar^ := nil;
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Inc(P);
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end;
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end;
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end.
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