Don't crash on exit when unregistering cover providers

src/covers/coverproviders.cpp

@@ -27,7 +27,7 @@ CoverProviders::CoverProviders()
 void CoverProviders::AddProvider(CoverProvider* provider) {
   {
     QMutexLocker locker(&mutex_);
-    cover_providers_.append(provider);
+    cover_providers_.insert(provider, provider->name());
   }
 
   qLog(Debug) << "Registered cover provider" << provider->name();
@@ -39,11 +39,20 @@ void CoverProviders::RemoveProvider(CoverProvider* provider) {
   if (!provider)
     return;
 
-  qLog(Debug) << "Unregistered cover provider" << provider->name();
+  // It's not safe to dereference provider at this pointbecause it might have
+  // already been destroyed.
+
+  QString name;
 
   {
     QMutexLocker locker(&mutex_);
-    cover_providers_.removeAll(provider);
+    name = cover_providers_.take(provider);
+  }
+
+  if (name.isNull()) {
+    qLog(Debug) << "Tried to remove a cover provider that was not registered";
+  } else {
+    qLog(Debug) << "Unregistered cover provider" << name;
   }
 }
 

src/covers/coverproviders.h

@@ -18,6 +18,7 @@
 #ifndef COVERPROVIDERS_H
 #define COVERPROVIDERS_H
 
+#include <QMap>
 #include <QMutex>
 #include <QObject>
 
@@ -44,7 +45,7 @@ public:
   void RemoveProvider(CoverProvider* provider);
 
   // Returns a list of cover providers
-  QList<CoverProvider*> List() const { return cover_providers_; }
+  QList<CoverProvider*> List() const { return cover_providers_.keys(); }
   // Returns true if this repository has at least one registered provider.
   bool HasAnyProviders() const { return !cover_providers_.isEmpty(); }
 
@@ -58,7 +59,7 @@ private:
   ~CoverProviders() {}
   Q_DISABLE_COPY(CoverProviders);
 
-  QList<CoverProvider*> cover_providers_;
+  QMap<CoverProvider*, QString> cover_providers_;
   QMutex mutex_;
 
   QAtomicInt next_id_;