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

2 files changed, 21 insertions, 5 deletions

diff --git a/apt-pkg/cachefile.cc b/apt-pkg/cachefile.cc
index a22804c36..9a1a6cfa9 100644
--- a/apt-pkg/cachefile.cc
+++ b/apt-pkg/cachefile.cc
@@ -35,12 +35,18 @@
 
 #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)
 {
@@ -59,8 +65,10 @@ 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		/*{{{*/
@@ -97,8 +105,11 @@ 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;
@@ -337,7 +348,11 @@ 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 097876b3a..ed5d5c57c 100644
--- a/apt-pkg/cachefile.h
+++ b/apt-pkg/cachefile.h
@@ -36,8 +36,9 @@ 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: