From 0c98c5e20bbee5602e1d4fa40d79ddd0c456417c Mon Sep 17 00:00:00 2001
From: Julian Andres Klode <julian.klode@canonical.com>
Date: Mon, 24 Sep 2018 11:38:55 +0200
Subject: pkgCacheFile: Only unlock in destructor if locked before

pkgCacheFile's destructor unlocks the system, which is confusing
if you did not open the cachefile with WithLock set. Create a private
data instance that holds the value of WithLock.

This regression was introduced in commit b2e465d6d32d2dc884f58b94acb7e35f671a87fe:

    Join with aliencode
    Author: jgg
    Date: 2001-02-20 07:03:16 GMT
    Join with aliencode

by replacing a "Lock" member that was only initialized when the lock
was taken by calls to Lock, UnLock; with the latter also taking place
if the former did not occur.

Regression-Of: b2e465d6d32d2dc884f58b94acb7e35f671a87fe
LP: #1794053
(cherry picked from commit e02297b8e22dae04872fe6fab6dba966de65dbba)
(cherry picked from commit 248f70d425c4cd865d4bd54ab1134ccff8b68e36)
---
 apt-pkg/cachefile.cc | 23 +++++++++++++++++++----
 apt-pkg/cachefile.h  |  3 ++-
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/apt-pkg/cachefile.cc b/apt-pkg/cachefile.cc
index b5f32fc29..9eb98927e 100644
--- a/apt-pkg/cachefile.cc
+++ b/apt-pkg/cachefile.cc
@@ -36,12 +36,18 @@
 
 #include <apti18n.h>
 									/*}}}*/
+
+struct pkgCacheFile::Private
+{
+   bool WithLock = false;
+};
+
 // CacheFile::CacheFile - Constructor					/*{{{*/
-pkgCacheFile::pkgCacheFile() : d(NULL), ExternOwner(false), Map(NULL), Cache(NULL),
+pkgCacheFile::pkgCacheFile() : d(new Private()), ExternOwner(false), Map(NULL), Cache(NULL),
 				DCache(NULL), SrcList(NULL), Policy(NULL)
 {
 }
-pkgCacheFile::pkgCacheFile(pkgDepCache * const Owner) : d(NULL), ExternOwner(true),
+pkgCacheFile::pkgCacheFile(pkgDepCache * const Owner) : d(new Private()), ExternOwner(true),
    Map(&Owner->GetCache().GetMap()), Cache(&Owner->GetCache()),
    DCache(Owner), SrcList(NULL), Policy(NULL)
 {
@@ -60,8 +66,10 @@ pkgCacheFile::~pkgCacheFile()
    }
    delete Policy;
    delete SrcList;
-   if (ExternOwner == false)
+   if (d->WithLock == true)
       _system->UnLock(true);
+
+   delete d;
 }
 									/*}}}*/
 // CacheFile::BuildCaches - Open and build the cache files		/*{{{*/
@@ -98,8 +106,11 @@ bool pkgCacheFile::BuildCaches(OpProgress *Progress, bool WithLock)
    }
 
    if (WithLock == true)
+   {
       if (_system->Lock() == false)
 	 return false;
+      d->WithLock = true;
+   }
 
    if (_error->PendingError() == true)
       return false;
@@ -338,7 +349,11 @@ void pkgCacheFile::Close()
       ExternOwner = false;
    delete Policy;
    delete SrcList;
-   _system->UnLock(true);
+   if (d->WithLock == true)
+   {
+      _system->UnLock(true);
+      d->WithLock = false;
+   }
 
    Map = NULL;
    DCache = NULL;
diff --git a/apt-pkg/cachefile.h b/apt-pkg/cachefile.h
index e23f37675..7e2319519 100644
--- a/apt-pkg/cachefile.h
+++ b/apt-pkg/cachefile.h
@@ -37,8 +37,9 @@ class OpProgress;
 
 class pkgCacheFile
 {
+   struct Private;
    /** \brief dpointer placeholder (for later in case we need it) */
-   void * const d;
+   Private *const d;
    bool ExternOwner;
 
    protected:
-- 
cgit v1.2.3