From a610eb7369be603460468f1e2ab894873a638ab0 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sat, 28 Apr 2012 22:25:19 +0000
Subject: [PATCH] Fix crash in wxFileConfig when deleting last entry of the
 root group.

This resulted in keeping a dangling pointer to the group line in
wxFileConfigGroup and any attempt to use it after this resulted in a crash.
Fix this by explicitly resetting the last line in this case.

Also add a unit test for this scenario.

Closes #14243.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71311 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/common/fileconf.cpp   |  5 +++++
 tests/config/fileconf.cpp | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/src/common/fileconf.cpp b/src/common/fileconf.cpp
index 75fcd7c88a..4b63270320 100644
--- a/src/common/fileconf.cpp
+++ b/src/common/fileconf.cpp
@@ -1818,6 +1818,11 @@ bool wxFileConfigGroup::DeleteEntry(const wxString& name)
       // pNewLast can be NULL here -- it's ok and can happen if we have no
       // entries left
       m_pLastEntry = pNewLast;
+
+      // For the root group only, we could be removing the first group line
+      // here, so update m_pLine to avoid keeping a dangling pointer.
+      if ( pLine == m_pLine )
+          SetLine(NULL);
     }
 
     m_pConfig->LineListRemove(pLine);
diff --git a/tests/config/fileconf.cpp b/tests/config/fileconf.cpp
index 7a9c2d73f6..a92bdb6afe 100644
--- a/tests/config/fileconf.cpp
+++ b/tests/config/fileconf.cpp
@@ -71,6 +71,7 @@ private:
         CPPUNIT_TEST( Save );
         CPPUNIT_TEST( DeleteEntry );
         CPPUNIT_TEST( DeleteAndWriteEntry );
+        CPPUNIT_TEST( DeleteLastRootEntry );
         CPPUNIT_TEST( DeleteGroup );
         CPPUNIT_TEST( DeleteAll );
         CPPUNIT_TEST( RenameEntry );
@@ -95,6 +96,7 @@ private:
     void Save();
     void DeleteEntry();
     void DeleteAndWriteEntry();
+    void DeleteLastRootEntry();
     void DeleteGroup();
     void DeleteAll();
     void RenameEntry();
@@ -376,6 +378,24 @@ void FileConfigTestCase::DeleteAndWriteEntry()
     wxVERIFY_FILECONFIG( "", fc );
 }
 
+void FileConfigTestCase::DeleteLastRootEntry()
+{
+    // This tests for the bug which occurred when the last entry of the root
+    // group was deleted: this corrupted internal state and resulted in a crash
+    // after trying to write the just deleted entry again.
+    wxStringInputStream sis("");
+    wxFileConfig fc(sis);
+
+    fc.Write("key", "value");
+    wxVERIFY_FILECONFIG( "key=value\n", fc );
+
+    fc.DeleteEntry("key");
+    wxVERIFY_FILECONFIG( "", fc );
+
+    fc.Write("key", "value");
+    wxVERIFY_FILECONFIG( "key=value\n", fc );
+}
+
 void FileConfigTestCase::DeleteGroup()
 {
     wxStringInputStream sis(testconfig);
-- 
2.45.2