+ Added .gz file stream support

fcl/inc/zstream.pp

@@ -1,388 +1,447 @@
-unit zstream;
-
-interface
-
-uses Sysutils, Classes,zlib;
-
-type
-  // Error reporting.
-
-  EZlibError = class(Exception);
-  ECompressionError = class(EZlibError);
-  EDecompressionError = class(EZlibError);
-
-  TCustomZlibStream = class(TStream)
-  private
-    FStrm: TStream;
-    FStrmPos: Integer;
-    FOnProgress: TNotifyEvent;
-    FZRec: TZStream;
-    FBuffer: array [Word] of Char;
-  protected
-    procedure Progress(Sender: TObject); dynamic;
-    property OnProgress: TNotifyEvent read FOnProgress write FOnProgress;
-    constructor Create(Strm: TStream);
-  end;
-
-  TCompressionLevel = (clNone, clFastest, clDefault, clMax);
-
-  TCompressionStream = class(TCustomZlibStream)
-  private
-    function GetCompressionRate: extended;
-  public
-    constructor Create(CompressionLevel: TCompressionLevel; Dest: TStream);
-    destructor Destroy; override;
-    function CompressionCheck(code: Integer): Integer;
-    procedure CompressBuf(const InBuf: Pointer; InBytes: Integer;
-                          var OutBuf: Pointer; var OutBytes: Integer);
-    function Read(var Buffer; Count: Longint): Longint; override;
-    function Write(const Buffer; Count: Longint): Longint; override;
-    function Seek(Offset: Longint; Origin: Word): Longint; override;
-    property CompressionRate: extended read GetCompressionRate;
-    property OnProgress;
-  end;
-
-  TDecompressionStream = class(TCustomZlibStream)
-  public
-    constructor Create(Source: TStream);
-    destructor Destroy; override;
-    function DecompressionCheck(code: Integer): Integer;
-    procedure DecompressBuf(const InBuf: Pointer; InBytes: Integer;
-    OutEstimate: Integer; var OutBuf: Pointer; var OutBytes: Integer);
-    function Read(var Buffer; Count: Longint): Longint; override;
-    function Write(const Buffer; Count: Longint): Longint; override;
-    function Seek(Offset: Longint; Origin: Word): Longint; override;
-    property OnProgress;
-  end;
-
-
-implementation
-
-Const 
-  ErrorStrings : array [0..6] of string = 
+unit zstream;
+
+interface
+
+uses Sysutils, Classes,zlib;
+{$H+}
+
+type
+  // Error reporting.
+
+  EZlibError = class(Exception);
+  ECompressionError = class(EZlibError);
+  EDecompressionError = class(EZlibError);
+
+  TCustomZlibStream = class(TStream)
+  private
+    FStrm: TStream;
+    FStrmPos: Integer;
+    FOnProgress: TNotifyEvent;
+    FZRec: TZStream;
+    FBuffer: array [Word] of Char;
+  protected
+    procedure Progress(Sender: TObject); dynamic;
+    property OnProgress: TNotifyEvent read FOnProgress write FOnProgress;
+    constructor Create(Strm: TStream);
+  end;
+
+  TCompressionLevel = (clNone, clFastest, clDefault, clMax);
+
+  TCompressionStream = class(TCustomZlibStream)
+  private
+    function GetCompressionRate: extended;
+    function CompressionCheck(code: Integer): Integer;
+    procedure CompressBuf(const InBuf: Pointer; InBytes: Integer;
+                          var OutBuf: Pointer; var OutBytes: Integer);
+  public
+    constructor Create(CompressionLevel: TCompressionLevel; Dest: TStream);
+    destructor Destroy; override;
+    function Read(var Buffer; Count: Longint): Longint; override;
+    function Write(const Buffer; Count: Longint): Longint; override;
+    function Seek(Offset: Longint; Origin: Word): Longint; override;
+    property CompressionRate: extended read GetCompressionRate;
+    property OnProgress;
+  end;
+
+  TDecompressionStream = class(TCustomZlibStream)
+  private 
+    function DecompressionCheck(code: Integer): Integer;
+    procedure DecompressBuf(const InBuf: Pointer; InBytes: Integer;
+    OutEstimate: Integer; var OutBuf: Pointer; var OutBytes: Integer);
+  public
+    constructor Create(Source: TStream);
+    destructor Destroy; override;
+    function Read(var Buffer; Count: Longint): Longint; override;
+    function Write(const Buffer; Count: Longint): Longint; override;
+    function Seek(Offset: Longint; Origin: Word): Longint; override;
+    property OnProgress;
+  end;
+
+  TGZOpenMode = (gzOpenRead,gzOpenWrite);
+  
+  TGZFileStream = Class(TStream)
+    Private
+    FOpenMode : TGZOpenmode;
+    FFIle : gzfile;
+    Public
+    Constructor Create(FileName: String;FileMode: TGZOpenMode);
+    Destructor Destroy;override;
+    Function Read(Var Buffer; Count : longint): longint;override;
+    function Write(const Buffer; Count: Longint): Longint; override;
+    function Seek(Offset: Longint; Origin: Word): Longint; override;
+    end;
+    
+
+implementation
+
+Const 
+  ErrorStrings : array [0..6] of string = 
     ('Unknown error %d','Z_ERRNO','Z_STREAM_ERROR',
-     'Z_DATA_ERROR','Z_MEM_ERROR','Z_BUF_ERROR','Z_VERSION_ERROR');
-
-Type PLongint = ^Longint;
-
-Function DGetmem (Size : Longint) : pointer;
-begin
-  Inc(Size,SizeOf(Longint));
-  GetMem(Result,Size);
-  If Result<>Nil then 
-    begin
-    Plongint(Result)^:=Size;
-    Inc(Result,SizeOf(Integer));
-    end;
-end;
-
-Procedure DFreeMem(P : Pointer);
-begin
-  // Get Stored length
-  Dec(P,SizeOf(Integer));
-  FreeMem(P,Plongint(P)^);
-end;
-
-Procedure DReallocMem (var P : Pointer; NewSize : Longint);
-  // Reallocates memory pointed to by P.
-Var T : pointer;
-    OldSize : longint;
-begin
-  // Should raise an exception if no memory.
-  T:=DGetMem(NewSize);
-  OldSize:=PLongint(P-SizeOf(Integer))^;
-  If oldSize<NewSize then
-    Move(P^,T^,OldSize)
-  else
-    Move(P^,T^,NewSize);
-  DFreeMem(P);
-end;
-
-function zlibAllocMem(AppData: Pointer; Items, Size: Integer): Pointer;cdecl;
-begin
-  Result:=DGetMem(Items*Size);
-end;
-
-procedure zlibFreeMem(AppData, Block: Pointer);cdecl;
-begin
-  DFreeMem(Block);
-end;
-
-
-procedure TCompressionStream.CompressBuf(const InBuf: Pointer; InBytes: Integer;
-                      var OutBuf: Pointer; var OutBytes: Integer);
-var
-  strm: TZStream;
-  P: Pointer;
-  oldout : longint;
-begin
-  FillChar(strm, sizeof(strm), 0);
-  strm.zalloc := @zlibAllocMem;
-  strm.zfree := @zlibFreeMem;
-  OutBytes := ((InBytes + (InBytes div 10) + 12) + 255) and not 255;
-  OutBuf:=DGetMem(OutBytes);
-  try
-    strm.next_in := InBuf;
-    strm.avail_in := InBytes;
-    strm.next_out := OutBuf;
-    strm.avail_out := OutBytes;
-    CompressionCheck(deflateInit_(strm, Z_BEST_COMPRESSION, zlibversion, sizeof(strm)));
-    try
-      while CompressionCheck(deflate(strm, Z_FINISH)) <> Z_STREAM_END do
-      begin
-        P := OutBuf;
-        Inc(OutBytes, 256);
-        DReallocMem(OutBuf,OutBytes);
-        strm.next_out := PChar(Integer(OutBuf) + (Integer(strm.next_out) - Integer(P)));
-        strm.avail_out := 256;
-      end;
-    finally
-      CompressionCheck(deflateEnd(strm));
-    end;
-    DReallocMem(OutBuf,strm.total_out);
-    OutBytes := strm.total_out;
-  except
-    DFreeMem(OutBuf);
-    raise;
-  end;
-end;
-
-
-procedure TDecompressionStream.DecompressBuf(const InBuf: Pointer; InBytes: Integer;
-       OutEstimate: Integer; var OutBuf: Pointer; var OutBytes: Integer);
-var
-  strm: TZStream;
-  P: Pointer;
-  BufInc: Integer;
-begin
-  FillChar(strm, sizeof(strm), 0);
-  strm.zalloc := @zlibAllocMem;
-  strm.zfree := @zlibFreeMem;
-  BufInc := (InBytes + 255) and not 255;
-  if OutEstimate = 0 then
-    OutBytes := BufInc
-  else
-    OutBytes := OutEstimate;
-  OutBuf:=DGetMem(OutBytes);
-  try
-    strm.next_in := InBuf;
-    strm.avail_in := InBytes;
-    strm.next_out := OutBuf;
-    strm.avail_out := OutBytes;
-    DecompressionCheck(inflateInit_(strm, zlibversion, sizeof(strm)));
-    try
-      while DecompressionCheck(inflate(strm, Z_FINISH)) <> Z_STREAM_END do
-      begin
-        P := OutBuf;
-        Inc(OutBytes, BufInc);
-        DReallocMem(OutBuf, OutBytes);
-        strm.next_out := PChar(Integer(OutBuf) + (Integer(strm.next_out) - Integer(P)));
-        strm.avail_out := BufInc;
-      end;
-    finally
-      DecompressionCheck(inflateEnd(strm));
-    end;
-    DReallocMem(OutBuf, strm.total_out);
-    OutBytes := strm.total_out;
-  except
-    DFreeMem(OutBuf);
-    raise;
-  end;
-end;
-
-
-// TCustomZlibStream
-
-constructor TCustomZLibStream.Create(Strm: TStream);
-begin
-  inherited Create;
-  FStrm := Strm;
-  FStrmPos := Strm.Position;
-  FZRec.zalloc := @zlibAllocMem;
-  FZRec.zfree := @zlibFreeMem;
-end;
-
-procedure TCustomZLibStream.Progress(Sender: TObject);
-begin
-  if Assigned(FOnProgress) then FOnProgress(Sender);
-end;
-
-
-// TCompressionStream
-
-constructor TCompressionStream.Create(CompressionLevel: TCompressionLevel;
-  Dest: TStream);
-const
-  Levels: array [TCompressionLevel] of ShortInt =
-    (Z_NO_COMPRESSION, Z_BEST_SPEED, Z_DEFAULT_COMPRESSION, Z_BEST_COMPRESSION);
-begin
-  inherited Create(Dest);
-  FZRec.next_out := FBuffer;
-  FZRec.avail_out := sizeof(FBuffer);
-  CompressionCheck(deflateInit_(FZRec, Levels[CompressionLevel], zlibversion, sizeof(FZRec)));
-end;
-
-destructor TCompressionStream.Destroy;
-begin
-  FZRec.next_in := nil;
-  FZRec.avail_in := 0;
-  try
-    if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
-    while (CompressionCheck(deflate(FZRec, Z_FINISH)) <> Z_STREAM_END)
-      and (FZRec.avail_out = 0) do
-    begin
-      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer));
-      FZRec.next_out := FBuffer;
-      FZRec.avail_out := sizeof(FBuffer);
-    end;
-    if FZRec.avail_out < sizeof(FBuffer) then
-      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer) - FZRec.avail_out);
-  finally
-    deflateEnd(FZRec);
-  end;
-  inherited Destroy;
-end;
-
-function TCompressionStream.CompressionCheck(code: Integer): Integer;
-begin
-  Result := code;
-  if (code < 0) then
-    if code < -6 then
-      raise ECompressionError.CreateFmt(Errorstrings[0],[Code])
-    else
-      raise ECompressionError.Create(ErrorStrings[Abs(Code)]);
-end;
-
-
-function TCompressionStream.Read(var Buffer; Count: Longint): Longint;
-begin
-  raise ECompressionError.Create('Invalid stream operation');
-end;
-
-function TCompressionStream.Write(const Buffer; Count: Longint): Longint;
-begin
-  FZRec.next_in := @Buffer;
-  FZRec.avail_in := Count;
-  if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
-  while (FZRec.avail_in > 0) do
-  begin
-    CompressionCheck(deflate(FZRec, 0));
-    if FZRec.avail_out = 0 then
-    begin
-      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer));
-      FZRec.next_out := FBuffer;
-      FZRec.avail_out := sizeof(FBuffer);
-      FStrmPos := FStrm.Position;
-      Progress(Self);
-    end;
-  end;
-  Result := Count;
-end;
-
-function TCompressionStream.Seek(Offset: Longint; Origin: Word): Longint;
-begin
-  if (Offset = 0) and (Origin = soFromCurrent) then
-    Result := FZRec.total_in
-  else
-    raise ECompressionError.Create('Invalid stream operation');
-end;
-
-function TCompressionStream.GetCompressionRate: extended;
-begin
-  Result:=0.0;
-{  With FZrec do
-    if total_in = 0 then
-      GetCompressionRate:=0.0
-    else
-      GetCompressionRate:=1.0E2*(1.0E0-(total_out/total_in));
-}
-end;
-
-
-// TDecompressionStream
-
-constructor TDecompressionStream.Create(Source: TStream);
-begin
-  inherited Create(Source);
-  FZRec.next_in := FBuffer;
-  FZRec.avail_in := 0;
-  DecompressionCheck(inflateInit_(FZRec, zlibversion, sizeof(FZRec)));
-end;
-
-destructor TDecompressionStream.Destroy;
-begin
-  inflateEnd(FZRec);
-  inherited Destroy;
-end;
-
-function TDecompressionStream.DecompressionCheck(code: Integer): Integer;
-begin
-  Result := code;
-  If Code<0 then
-    if code < -6 then
-      raise EDecompressionError.CreateFmt(Errorstrings[0],[Code])
-    else
-      raise EDecompressionError.Create(ErrorStrings[Abs(Code)]);
-end;
-
-function TDecompressionStream.Read(var Buffer; Count: Longint): Longint;
-begin
-  FZRec.next_out := @Buffer;
-  FZRec.avail_out := Count;
-  if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
-  while (FZRec.avail_out > 0) do
-  begin
-    if FZRec.avail_in = 0 then
-    begin
-      FZRec.avail_in := FStrm.Read(FBuffer, sizeof(FBuffer));
-      if FZRec.avail_in = 0 then
-        begin
-          Result := Count - FZRec.avail_out;
-          Exit;
-        end;
-      FZRec.next_in := FBuffer;
-      FStrmPos := FStrm.Position;
-      Progress(Self);
-    end;
-    DeCompressionCheck(inflate(FZRec, 0));
-  end;
-  Result := Count;
-end;
-
-function TDecompressionStream.Write(const Buffer; Count: Longint): Longint;
-begin
-  raise EDecompressionError.Create('Invalid stream operation');
-end;
-
-function TDecompressionStream.Seek(Offset: Longint; Origin: Word): Longint;
-var
-  I: Integer;
-  Buf: array [0..4095] of Char;
-begin
-  if (Offset = 0) and (Origin = soFromBeginning) then
-  begin
-    DecompressionCheck(inflateReset(FZRec));
-    FZRec.next_in := FBuffer;
-    FZRec.avail_in := 0;
-    FStrm.Position := 0;
-    FStrmPos := 0;
-  end
-  else if ( (Offset >= 0) and (Origin = soFromCurrent)) or
-          ( ((Offset - FZRec.total_out) > 0) and (Origin = soFromBeginning)) then
-  begin
-    if Origin = soFromBeginning then Dec(Offset, FZRec.total_out);
-    if Offset > 0 then
-    begin
-      for I := 1 to Offset div sizeof(Buf) do
-        ReadBuffer(Buf, sizeof(Buf));
-      ReadBuffer(Buf, Offset mod sizeof(Buf));
-    end;
-  end
-  else
-    raise EDecompressionError.Create('Invalid stream operation');
-  Result := FZRec.total_out;
-end;
-
-
-
-end.
+     'Z_DATA_ERROR','Z_MEM_ERROR','Z_BUF_ERROR','Z_VERSION_ERROR');
+  SCouldntOpenFile = 'Couldn''t open file : %s';
+  SReadOnlyStream = 'Decompression streams are read-only';
+  SWriteOnlyStream = 'Compression streams are write-only';
+  SSeekError = 'Compression stream seek error';  
+  SInvalidSeek = 'Invalid Compression seek operation';
+  
+Type PLongint = ^Longint;
+
+Function DGetmem (Size : Longint) : pointer;
+begin
+  Inc(Size,SizeOf(Longint));
+  GetMem(Result,Size);
+  If Result<>Nil then 
+    begin
+    Plongint(Result)^:=Size;
+    Inc(Result,SizeOf(Integer));
+    end;
+end;
+
+Procedure DFreeMem(P : Pointer);
+begin
+  // Get Stored length
+  Dec(P,SizeOf(Integer));
+  FreeMem(P,Plongint(P)^);
+end;
+
+Procedure DReallocMem (var P : Pointer; NewSize : Longint);
+  // Reallocates memory pointed to by P.
+Var T : pointer;
+    OldSize : longint;
+begin
+  // Should raise an exception if no memory.
+  T:=DGetMem(NewSize);
+  OldSize:=PLongint(P-SizeOf(Integer))^;
+  If oldSize<NewSize then
+    Move(P^,T^,OldSize)
+  else
+    Move(P^,T^,NewSize);
+  DFreeMem(P);
+end;
+
+function zlibAllocMem(AppData: Pointer; Items, Size: Integer): Pointer;cdecl;
+begin
+  Result:=DGetMem(Items*Size);
+end;
+
+procedure zlibFreeMem(AppData, Block: Pointer);cdecl;
+begin
+  DFreeMem(Block);
+end;
+
+
+procedure TCompressionStream.CompressBuf(const InBuf: Pointer; InBytes: Integer;
+                      var OutBuf: Pointer; var OutBytes: Integer);
+var
+  strm: TZStream;
+  P: Pointer;
+  oldout : longint;
+begin
+  FillChar(strm, sizeof(strm), 0);
+  strm.zalloc := @zlibAllocMem;
+  strm.zfree := @zlibFreeMem;
+  OutBytes := ((InBytes + (InBytes div 10) + 12) + 255) and not 255;
+  OutBuf:=DGetMem(OutBytes);
+  try
+    strm.next_in := InBuf;
+    strm.avail_in := InBytes;
+    strm.next_out := OutBuf;
+    strm.avail_out := OutBytes;
+    CompressionCheck(deflateInit_(strm, Z_BEST_COMPRESSION, zlibversion, sizeof(strm)));
+    try
+      while CompressionCheck(deflate(strm, Z_FINISH)) <> Z_STREAM_END do
+      begin
+        P := OutBuf;
+        Inc(OutBytes, 256);
+        DReallocMem(OutBuf,OutBytes);
+        strm.next_out := PChar(Integer(OutBuf) + (Integer(strm.next_out) - Integer(P)));
+        strm.avail_out := 256;
+      end;
+    finally
+      CompressionCheck(deflateEnd(strm));
+    end;
+    DReallocMem(OutBuf,strm.total_out);
+    OutBytes := strm.total_out;
+  except
+    DFreeMem(OutBuf);
+    raise;
+  end;
+end;
+
+
+procedure TDecompressionStream.DecompressBuf(const InBuf: Pointer; InBytes: Integer;
+       OutEstimate: Integer; var OutBuf: Pointer; var OutBytes: Integer);
+var
+  strm: TZStream;
+  P: Pointer;
+  BufInc: Integer;
+begin
+  FillChar(strm, sizeof(strm), 0);
+  strm.zalloc := @zlibAllocMem;
+  strm.zfree := @zlibFreeMem;
+  BufInc := (InBytes + 255) and not 255;
+  if OutEstimate = 0 then
+    OutBytes := BufInc
+  else
+    OutBytes := OutEstimate;
+  OutBuf:=DGetMem(OutBytes);
+  try
+    strm.next_in := InBuf;
+    strm.avail_in := InBytes;
+    strm.next_out := OutBuf;
+    strm.avail_out := OutBytes;
+    DecompressionCheck(inflateInit_(strm, zlibversion, sizeof(strm)));
+    try
+      while DecompressionCheck(inflate(strm, Z_FINISH)) <> Z_STREAM_END do
+      begin
+        P := OutBuf;
+        Inc(OutBytes, BufInc);
+        DReallocMem(OutBuf, OutBytes);
+        strm.next_out := PChar(Integer(OutBuf) + (Integer(strm.next_out) - Integer(P)));
+        strm.avail_out := BufInc;
+      end;
+    finally
+      DecompressionCheck(inflateEnd(strm));
+    end;
+    DReallocMem(OutBuf, strm.total_out);
+    OutBytes := strm.total_out;
+  except
+    DFreeMem(OutBuf);
+    raise;
+  end;
+end;
+
+
+// TCustomZlibStream
+
+constructor TCustomZLibStream.Create(Strm: TStream);
+begin
+  inherited Create;
+  FStrm := Strm;
+  FStrmPos := Strm.Position;
+  FZRec.zalloc := @zlibAllocMem;
+  FZRec.zfree := @zlibFreeMem;
+end;
+
+procedure TCustomZLibStream.Progress(Sender: TObject);
+begin
+  if Assigned(FOnProgress) then FOnProgress(Sender);
+end;
+
+
+// TCompressionStream
+
+constructor TCompressionStream.Create(CompressionLevel: TCompressionLevel;
+  Dest: TStream);
+const
+  Levels: array [TCompressionLevel] of ShortInt =
+    (Z_NO_COMPRESSION, Z_BEST_SPEED, Z_DEFAULT_COMPRESSION, Z_BEST_COMPRESSION);
+begin
+  inherited Create(Dest);
+  FZRec.next_out := FBuffer;
+  FZRec.avail_out := sizeof(FBuffer);
+  CompressionCheck(deflateInit_(FZRec, Levels[CompressionLevel], zlibversion, sizeof(FZRec)));
+end;
+
+destructor TCompressionStream.Destroy;
+begin
+  FZRec.next_in := nil;
+  FZRec.avail_in := 0;
+  try
+    if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
+    while (CompressionCheck(deflate(FZRec, Z_FINISH)) <> Z_STREAM_END)
+      and (FZRec.avail_out = 0) do
+    begin
+      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer));
+      FZRec.next_out := FBuffer;
+      FZRec.avail_out := sizeof(FBuffer);
+    end;
+    if FZRec.avail_out < sizeof(FBuffer) then
+      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer) - FZRec.avail_out);
+  finally
+    deflateEnd(FZRec);
+  end;
+  inherited Destroy;
+end;
+
+function TCompressionStream.CompressionCheck(code: Integer): Integer;
+begin
+  Result := code;
+  if (code < 0) then
+    if code < -6 then
+      raise ECompressionError.CreateFmt(Errorstrings[0],[Code])
+    else
+      raise ECompressionError.Create(ErrorStrings[Abs(Code)]);
+end;
+
+
+function TCompressionStream.Read(var Buffer; Count: Longint): Longint;
+begin
+  raise ECompressionError.Create('Invalid stream operation');
+end;
+
+function TCompressionStream.Write(const Buffer; Count: Longint): Longint;
+begin
+  FZRec.next_in := @Buffer;
+  FZRec.avail_in := Count;
+  if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
+  while (FZRec.avail_in > 0) do
+  begin
+    CompressionCheck(deflate(FZRec, 0));
+    if FZRec.avail_out = 0 then
+    begin
+      FStrm.WriteBuffer(FBuffer, sizeof(FBuffer));
+      FZRec.next_out := FBuffer;
+      FZRec.avail_out := sizeof(FBuffer);
+      FStrmPos := FStrm.Position;
+      Progress(Self);
+    end;
+  end;
+  Result := Count;
+end;
+
+function TCompressionStream.Seek(Offset: Longint; Origin: Word): Longint;
+begin
+  if (Offset = 0) and (Origin = soFromCurrent) then
+    Result := FZRec.total_in
+  else
+    raise ECompressionError.Create(SInvalidSeek);
+end;
+
+function TCompressionStream.GetCompressionRate: extended;
+begin
+  Result:=0.0;
+{  With FZrec do
+    if total_in = 0 then
+      GetCompressionRate:=0.0
+    else
+      GetCompressionRate:=1.0E2*(1.0E0-(total_out/total_in));
+}
+end;
+
+
+// TDecompressionStream
+
+constructor TDecompressionStream.Create(Source: TStream);
+begin
+  inherited Create(Source);
+  FZRec.next_in := FBuffer;
+  FZRec.avail_in := 0;
+  DecompressionCheck(inflateInit_(FZRec, zlibversion, sizeof(FZRec)));
+end;
+
+destructor TDecompressionStream.Destroy;
+begin
+  inflateEnd(FZRec);
+  inherited Destroy;
+end;
+
+function TDecompressionStream.DecompressionCheck(code: Integer): Integer;
+begin
+  Result := code;
+  If Code<0 then
+    if code < -6 then
+      raise EDecompressionError.CreateFmt(Errorstrings[0],[Code])
+    else
+      raise EDecompressionError.Create(ErrorStrings[Abs(Code)]);
+end;
+
+function TDecompressionStream.Read(var Buffer; Count: Longint): Longint;
+begin
+  FZRec.next_out := @Buffer;
+  FZRec.avail_out := Count;
+  if FStrm.Position <> FStrmPos then FStrm.Position := FStrmPos;
+  while (FZRec.avail_out > 0) do
+  begin
+    if FZRec.avail_in = 0 then
+    begin
+      FZRec.avail_in := FStrm.Read(FBuffer, sizeof(FBuffer));
+      if FZRec.avail_in = 0 then
+        begin
+          Result := Count - FZRec.avail_out;
+          Exit;
+        end;
+      FZRec.next_in := FBuffer;
+      FStrmPos := FStrm.Position;
+      Progress(Self);
+    end;
+    DeCompressionCheck(inflate(FZRec, 0));
+  end;
+  Result := Count;
+end;
+
+function TDecompressionStream.Write(const Buffer; Count: Longint): Longint;
+begin
+  raise EDecompressionError.Create('Invalid stream operation');
+end;
+
+function TDecompressionStream.Seek(Offset: Longint; Origin: Word): Longint;
+var
+  I: Integer;
+  Buf: array [0..4095] of Char;
+begin
+  if (Offset = 0) and (Origin = soFromBeginning) then
+  begin
+    DecompressionCheck(inflateReset(FZRec));
+    FZRec.next_in := FBuffer;
+    FZRec.avail_in := 0;
+    FStrm.Position := 0;
+    FStrmPos := 0;
+  end
+  else if ( (Offset >= 0) and (Origin = soFromCurrent)) or
+          ( ((Offset - FZRec.total_out) > 0) and (Origin = soFromBeginning)) then
+  begin
+    if Origin = soFromBeginning then Dec(Offset, FZRec.total_out);
+    if Offset > 0 then
+    begin
+      for I := 1 to Offset div sizeof(Buf) do
+        ReadBuffer(Buf, sizeof(Buf));
+      ReadBuffer(Buf, Offset mod sizeof(Buf));
+    end;
+  end
+  else
+    raise EDecompressionError.Create(SInvalidSeek);
+  Result := FZRec.total_out;
+end;
+
+// TGZFileStream
+
+Constructor TGZFileStream.Create(FileName: String;FileMode: TGZOpenMode);
+
+Const OpenStrings : array[TGZOpenMode] of pchar = ('rb','wb');
+
+begin
+   FOpenMode:=FileMode;
+   FFile:=gzopen (Pchar(FileName),Openstrings[FileMode]);
+   If FFile=Nil then
+     Raise ezlibError.CreateFmt (SCouldntOpenFIle,[FileName]);
+end;
+
+Destructor TGZFileStream.Destroy;
+begin
+  gzclose(FFile);
+  Inherited Destroy;
+end;
+
+Function TGZFileStream.Read(Var Buffer; Count : longint): longint;
+begin
+  If FOpenMode=gzOpenWrite then
+    Raise ezliberror.create(SWriteOnlyStream);
+  Result:=gzRead(FFile,@Buffer,Count);
+end;
+
+function TGZFileStream.Write(const Buffer; Count: Longint): Longint;
+begin
+  If FOpenMode=gzOpenRead then
+    Raise EzlibError.Create(SReadonlyStream);
+  Result:=gzWrite(FFile,@Buffer,Count);
+end;
+
+function TGZFileStream.Seek(Offset: Longint; Origin: Word): Longint;
+begin
+  Result:=gzseek(FFile,Offset,Origin);
+  If Result=-1 then
+    Raise eZlibError.Create(SSeekError);
+end;
+
+end.