Merge pull request #7 from formeo/feature/refactoring

parser add

Author: formeo

.gitignore

@@ -64,5 +64,5 @@ __recovery/
 
 # Castalia statistics file (since XE7 Castalia is distributed with Delphi)
 *.stat
-* .idea
-* 
+.idea
+

README.md

@@ -82,3 +82,4 @@ MIT
 ## Author
 
 Gordienko Roman
+

uRecordParser.pas

@@ -0,0 +1,133 @@
+unit uRecordParser;
+
+interface
+
+uses
+  Windows, SysUtils, uStructs, uDataPage;
+
+const
+  recDeleted = $01; // Çàïèñü ïîìå÷åíà êàê óäàë¸ííàÿ
+  recModified = $02; // Çàïèñü áûëà ìîäèôèöèðîâàíà
+  recHasSegment = $04; // Çàïèñü ñîäåðæèò ñåãìåíò (÷àñòü BLOB)
+  recHasNulls = $08; // Çàïèñü ñîäåðæèò NULL çíà÷åíèÿ
+  recVersioned = $10; // Çàïèñü âåðñèîíèðîâàíà (MVCC)
+  recLocalMod = $20; // Ëîêàëüíàÿ ìîäèôèêàöèÿ
+  recRemoteMod = $40; // Óäàë¸ííàÿ ìîäèôèêàöèÿ
+  recLastForm = $80; // Ïîñëåäíÿÿ ôîðìà çàïèñè (â öåïî÷êå?)
+
+
+  MIN_REC_HEADER_SIZE = 18;
+
+type
+
+  TRecordHeader = record
+    Flags: UShort;            // rec_flags
+    TransactionID: SLong;     // rec_transaction
+    BackPointer: SLong;       // rec_back (SLONG - ýòî êîäèðîâàíèå PageNum è SlotNum)
+    NextPointer: SLong;       // rec_next (SLONG - êîäèðîâàíèå)
+    Format: UShort;           // rec_format
+    DataLength: UShort;       // rec_length
+  end;
+
+  TParsedRecordFragment = record
+    Header: TRecordHeader;
+    Data: TBytes;             // Ôàêòè÷åñêèå äàííûå çàïèñè (rec_data)
+    OffsetInPage: Word;       // Ñìåùåíèå ôðàãìåíòà â èñõîäíîé Data Page
+    IsDeleted: Boolean;       // Óäîáíîå ïîëå: ðåçóëüòàò ïðîâåðêè Flags
+    // PageNum, SlotNum: Integer; // Ìîæíî äîáàâèòü, åñëè ðàñêîäèðóåì rec_back/next
+  end;
+
+
+  TParsedRecordFragmentArray = array of TParsedRecordFragment;
+
+
+  TRecordParser = class
+  private
+    // Âíóòðåííÿÿ ôóíêöèÿ äëÿ èçâëå÷åíèÿ çàãîëîâêà èç áàéòîâ
+    function GetRecordHeaderFromBytes(const RecordFragmentData: TBytes): TRecordHeader;
+  public
+    // Ïàðñèò îäèí ôðàãìåíò çàïèñè (TRecordFragment èç uDataPage)
+    // Âõîä: RawFragmentData - áàéòû ôðàãìåíòà (TRecordFragment.Data)
+    //       FragmentOffset - ñìåùåíèå ýòîãî ôðàãìåíòà íà ñòðàíèöå (TRecordFragment.Offset)
+    // Âîçâðàò: TParsedRecordFragment ñ ðàñïàðñåííûìè äàííûìè
+    function ParseRecordFragment(const RawFragmentData: TBytes; FragmentOffset: Word): TParsedRecordFragment;
+
+    // Ïàðñèò ìàññèâ ôðàãìåíòîâ çàïèñåé (íàïðèìåð, ðåçóëüòàò uDataPage.ExtractDataFragments)
+    // Âõîä: RawFragments - ìàññèâ TRecordFragment
+    // Âîçâðàò: ìàññèâ TParsedRecordFragmentArray
+    function ParseRecordFragments(const RawFragments: TRecordFragmentsArray): TParsedRecordFragmentArray;
+
+    // Âñïîìîãàòåëüíàÿ ôóíêöèÿ: ïðîâåðÿåò, ïîìå÷åíà ëè âåðñèÿ êàê óäàë¸ííàÿ
+    function IsRecordDeleted(const Header: TRecordHeader): Boolean;
+
+    // Âñïîìîãàòåëüíàÿ ôóíêöèÿ: ïðîâåðÿåò, âåðñèîíèðîâàíà ëè çàïèñü
+    function IsRecordVersioned(const Header: TRecordHeader): Boolean;
+  end;
+
+implementation
+
+function TRecordParser.GetRecordHeaderFromBytes(const RecordFragmentData: TBytes): TRecordHeader;
+var
+  Offset: Integer;
+begin
+  if Length(RecordFragmentData) < MIN_REC_HEADER_SIZE then
+    raise Exception.Create('Record fragment data too small for record header.');
+
+  Offset := 0;
+  Result.Flags := PWord(@RecordFragmentData[Offset])^;
+  Inc(Offset, 2);
+
+  Result.TransactionID := PLongInt(@RecordFragmentData[Offset])^;
+  Inc(Offset, 4);
+
+  Result.BackPointer := PLongInt(@RecordFragmentData[Offset])^;
+  Inc(Offset, 4);
+
+  Result.NextPointer := PLongInt(@RecordFragmentData[Offset])^;
+  Inc(Offset, 4);
+
+  Result.Format := PWord(@RecordFragmentData[Offset])^;
+  Inc(Offset, 2);
+
+  Result.DataLength := PWord(@RecordFragmentData[Offset])^;
+  Inc(Offset, 2);
+
+  // Ïðîâåðèì, ÷òî äëèíà äàííûõ íå âûõîäèò çà ïðåäåëû áóôåðà
+  if Offset + Result.DataLength > Length(RecordFragmentData) then
+    raise Exception.Create('Record header specifies data length exceeding fragment buffer size.');
+end;
+
+function TRecordParser.ParseRecordFragment(const RawFragmentData: TBytes; FragmentOffset: Word): TParsedRecordFragment;
+begin
+  Result.Header := GetRecordHeaderFromBytes(RawFragmentData);
+  Result.OffsetInPage := FragmentOffset;
+  Result.IsDeleted := IsRecordDeleted(Result.Header);
+
+  // Êîïèðóåì äàííûå çàïèñè (rec_data)
+  SetLength(Result.Data, Result.Header.DataLength);
+  if Result.Header.DataLength > 0 then
+    Move(RawFragmentData[MIN_REC_HEADER_SIZE], Result.Data[0], Result.Header.DataLength);
+end;
+
+function TRecordParser.ParseRecordFragments(const RawFragments: TRecordFragmentsArray): TParsedRecordFragmentArray;
+var
+  i: Integer;
+begin
+  SetLength(Result, Length(RawFragments));
+  for i := 0 to High(RawFragments) do
+  begin
+    Result[i] := ParseRecordFragment(RawFragments[i].Data, RawFragments[i].Offset);
+  end;
+end;
+
+function TRecordParser.IsRecordDeleted(const Header: TRecordHeader): Boolean;
+begin
+  Result := (Header.Flags and recDeleted) <> 0;
+end;
+
+function TRecordParser.IsRecordVersioned(const Header: TRecordHeader): Boolean;
+begin
+  Result := (Header.Flags and recVersioned) <> 0;
+end;
+
+end.