From 7e9e0e1965304eb5d73f1b91bafb3207dd3894d0 Mon Sep 17 00:00:00 2001
From: michael <michael@freepascal.org>
Date: Sun, 6 Oct 2019 13:11:17 +0000
Subject: [PATCH] * Fix bug #0030379: detect circular refences

git-svn-id: trunk@43143 -
---
 packages/fcl-db/src/base/datasource.inc | 15 ++++++++++++++-
 packages/fcl-db/src/base/db.pas         |  2 +-
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/packages/fcl-db/src/base/datasource.inc b/packages/fcl-db/src/base/datasource.inc
index 2e613dfb45..6836e47133 100644
--- a/packages/fcl-db/src/base/datasource.inc
+++ b/packages/fcl-db/src/base/datasource.inc
@@ -559,10 +559,21 @@ begin
 end;
 
 
-Function TDataSource.IsLinkedTo(ADataSet: TDataSet): Boolean;
+Function TDataSource.IsLinkedTo(ADataset: TDataSet): Boolean;
+
+var
+  DS: TDataSource;
 
 begin
   Result:=False;
+  Repeat
+    DS:=aDataset.GetDataSource;
+    Result:=(DS=Self);
+    if Assigned(DS) then
+      aDataSet := DS.DataSet
+    else
+      aDataSet := Nil;
+  Until Result or (aDataset=Nil)
 end;
 
 
@@ -615,6 +626,8 @@ begin
     End;
   If ADataset<>Nil Then
     begin
+    if IsLinkedTo(aDataset) then
+      DatabaseError(SErrCircularDataSourceReferenceNotAllowed,Self);
     FDataSet:=ADataset;
     ADataset.RegisterDatasource(Self);
     ProcessEvent(deUpdateState,0);
diff --git a/packages/fcl-db/src/base/db.pas b/packages/fcl-db/src/base/db.pas
index 3cd68cd902..10defd95ec 100644
--- a/packages/fcl-db/src/base/db.pas
+++ b/packages/fcl-db/src/base/db.pas
@@ -1926,7 +1926,7 @@ type
     constructor Create(AOwner: TComponent); override;
     destructor Destroy; override;
     procedure Edit;
-    function IsLinkedTo(ADataSet: TDataSet): Boolean;
+    function IsLinkedTo(ADataset: TDataSet): Boolean;
     property State: TDataSetState read FState;
   published
     property AutoEdit: Boolean read FAutoEdit write FAutoEdit default True;