* another patch for seeking in compressed streams by Danny Milosavljevic, resolves #12830

git-svn-id: trunk@12705 -

.gitattributes

@@ -7694,6 +7694,7 @@ tests/test/packages/hash/tmdtest.pp svneol=native#text/plain
 tests/test/packages/webtbs/tw10045.pp svneol=native#text/plain
 tests/test/packages/webtbs/tw11142.pp svneol=native#text/plain
 tests/test/packages/webtbs/tw11570.pp svneol=native#text/plain
+tests/test/packages/webtbs/tw12830.pp svneol=native#text/plain
 tests/test/packages/webtbs/tw1808.pp svneol=native#text/plain
 tests/test/packages/webtbs/tw3820.pp svneol=native#text/plain
 tests/test/packages/win-base/tdispvar1.pp svneol=native#text/plain

packages/paszlib/src/zstream.pp

@@ -70,6 +70,7 @@ type
           raw_read,compressed_read:longint;
           skipheader:boolean;
           procedure reset;
+          function GetPosition() : Int64; override;
         public
           constructor create(Asource:Tstream;Askipheader:boolean=false);
           destructor destroy;override;
@@ -321,6 +322,11 @@ begin
     raise Edecompressionerror.create(zerror(err));
 end;
 
+function Tdecompressionstream.GetPosition() : Int64; 
+begin
+  GetPosition := raw_read;
+end;
+
 function Tdecompressionstream.seek(offset:longint;origin:word):longint;
 
 var c:longint;
@@ -330,7 +336,7 @@ begin
      ((origin=sofromcurrent) and (offset+raw_read>=0)) then
     begin
       if origin = sofromcurrent then 
-        seek := compressed_read - offset
+        seek := raw_read + offset
       else
         seek := offset;
         

tests/test/packages/webtbs/tw12830.pp

@@ -0,0 +1,22 @@
+
+{$ASSERTIONS ON}
+
+uses zstream, sysutils, classes;
+
+var
+  fEncoder : zstream.Tcompressionstream;
+  fDecoder : zstream.Tdecompressionstream;
+  fExpectedString : Shortstring;
+  fCompressedStream : TStream;
+  fBuffer : array[0..9] of Char;
+begin
+  fCompressedStream := TMemoryStream.Create();
+  fExpectedString := 'test me test me I hope this is compressible test me compressible is test me';
+  fEncoder := zstream.Tcompressionstream.Create(clMax, fCompressedStream);
+  fEncoder.Write(fExpectedString[1], Length(fExpectedString));
+  FreeAndNil(fEncoder);
+  fCompressedStream.Position := 0;
+  fDecoder := zstream.Tdecompressionstream.Create(fCompressedStream);
+  fDecoder.Read(fBuffer, 10);
+  assert(fDecoder.Position = 10);
+end.