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{
This file is part of the Free Pascal run time library.
Copyright (c) 1999-2000 by Michael Van Canneyt
Implementation of pipe stream.
See the file COPYING.FPC, included in this distribution,
for details about the copyright.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
**********************************************************************}
{$mode objfpc}
Unit Pipes;
Interface
Uses sysutils,Classes;
Type
EPipeError = Class(EStreamError);
EPipeSeek = Class (EPipeError);
EPipeCreation = Class (EPipeError);
{ TInputPipeStream }
TInputPipeStream = Class(THandleStream)
Private
FPos : Int64;
function GetNumBytesAvailable: DWord;
protected
function GetPosition: Int64; override;
procedure InvalidSeek; override;
public
destructor Destroy; override;
Function Write (Const Buffer; Count : Longint) :Longint; Override;
function Seek(const Offset: int64; Origin: TSeekOrigin): int64; override;
Function Read (Var Buffer; Count : Longint) : longint; Override;
property NumBytesAvailable: DWord read GetNumBytesAvailable;
end;
TOutputPipeStream = Class(THandleStream)
Public
destructor Destroy; override;
function Seek(const Offset: int64; Origin: TSeekOrigin): int64; override;
Function Read (Var Buffer; Count : Longint) : longint; Override;
end;
Function CreatePipeHandles (Var Inhandle,OutHandle : THandle; APipeBufferSize : Cardinal = 1024) : Boolean;
Procedure CreatePipeStreams (Var InPipe : TInputPipeStream;
Var OutPipe : TOutputPipeStream);
Const EPipeMsg = 'Failed to create pipe.';
ENoSeekMsg = 'Cannot seek on pipes';
Implementation
{$i pipes.inc}
Procedure CreatePipeStreams (Var InPipe : TInputPipeStream;
Var OutPipe : TOutputPipeStream);
Var InHandle,OutHandle : THandle;
begin
if CreatePipeHandles (InHandle, OutHandle) then
begin
InPipe:=TInputPipeStream.Create (InHandle);
OutPipe:=TOutputPipeStream.Create (OutHandle);
end
Else
Raise EPipeCreation.Create (EPipeMsg)
end;
destructor TInputPipeStream.Destroy;
begin
PipeClose (Handle);
inherited;
end;
Function TInputPipeStream.Write (Const Buffer; Count : Longint) : longint;
begin
{$ifdef ver2_2_0}
raise EStreamError.Create( 'Cannot write to InputPipeStream');
{$else}
WriteNotImplemented;
{$endif}
Result := 0;
end;
Function TInputPipeStream.Read (Var Buffer; Count : Longint) : longint;
begin
Result:=Inherited Read(Buffer,Count);
Inc(FPos,Result);
end;
function TInputPipeStream.Seek(const Offset: int64; Origin: TSeekOrigin): int64;
begin
FakeSeekForward(Offset,Origin,FPos);
Result:=FPos;
end;
destructor TOutputPipeStream.Destroy;
begin
PipeClose (Handle);
inherited;
end;
Function TOutputPipeStream.Read(Var Buffer; Count : Longint) : longint;
begin
{$ifdef ver2_2_0}
raise EStreamError.Create( 'Cannot read from OutputPipeStream');
{$else}
ReadNotImplemented;
{$endif}
Result := 0;
end;
function TOutputPipeStream.Seek(const Offset: int64; Origin: TSeekOrigin): int64;
begin
InvalidSeek;
end;
end.
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