db/Plugin: use std::unique_ptr<> to manage Database pointers

src/db/plugins/ProxyDatabasePlugin.cxx

@@ -112,10 +112,10 @@ public:
 	ProxyDatabase(EventLoop &_loop, DatabaseListener &_listener,
 		      const ConfigBlock &block);
 
-	static Database *Create(EventLoop &main_event_loop,
-				EventLoop &io_event_loop,
-				DatabaseListener &listener,
-				const ConfigBlock &block);
+	static DatabasePtr Create(EventLoop &main_event_loop,
+				  EventLoop &io_event_loop,
+				  DatabaseListener &listener,
+				  const ConfigBlock &block);
 
 	void Open() override;
 	void Close() noexcept override;
@@ -440,12 +440,12 @@ ProxyDatabase::ProxyDatabase(EventLoop &_loop, DatabaseListener &_listener,
 {
 }
 
-Database *
+DatabasePtr
 ProxyDatabase::Create(EventLoop &loop, EventLoop &,
 		      DatabaseListener &listener,
 		      const ConfigBlock &block)
 {
-	return new ProxyDatabase(loop, listener, block);
+	return std::make_unique<ProxyDatabase>(loop, listener, block);
 }
 
 void

src/db/plugins/simple/Directory.cxx

@@ -45,8 +45,6 @@ Directory::Directory(std::string &&_path_utf8, Directory *_parent) noexcept
 
 Directory::~Directory() noexcept
 {
-	delete mounted_database;
-
 	songs.clear_and_dispose(Song::Disposer());
 	children.clear_and_dispose(DeleteDisposer());
 }

src/db/plugins/simple/Directory.hxx

@@ -23,6 +23,7 @@
 #include "util/Compiler.h"
 #include "db/Visitor.hxx"
 #include "db/PlaylistVector.hxx"
+#include "db/Ptr.hxx"
 #include "Song.hxx"
 
 #include <boost/intrusive/list.hpp>
@@ -43,7 +44,6 @@ static constexpr unsigned DEVICE_INARCHIVE = -1;
 static constexpr unsigned DEVICE_CONTAINER = -2;
 
 class SongFilter;
-class Database;
 
 struct Directory {
 	static constexpr auto link_mode = boost::intrusive::normal_link;
@@ -96,7 +96,7 @@ struct Directory {
 	 * If this is not nullptr, then this directory does not really
 	 * exist, but is a mount point for another #Database.
 	 */
-	Database *mounted_database = nullptr;
+	DatabasePtr mounted_database;
 
 public:
 	Directory(std::string &&_path_utf8, Directory *_parent) noexcept;

src/db/plugins/simple/SimpleDatabasePlugin.cxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -84,12 +84,12 @@ inline SimpleDatabase::SimpleDatabase(AllocatedPath &&_path,
 	 prefixed_light_song(nullptr) {
 }
 
-Database *
+DatabasePtr
 SimpleDatabase::Create(EventLoop &, EventLoop &,
 		       gcc_unused DatabaseListener &listener,
 		       const ConfigBlock &block)
 {
-	return new SimpleDatabase(block);
+	return std::make_unique<SimpleDatabase>(block);
 }
 
 void
@@ -390,13 +390,13 @@ SimpleDatabase::Save()
 }
 
 void
-SimpleDatabase::Mount(const char *uri, Database *db)
+SimpleDatabase::Mount(const char *uri, DatabasePtr db)
 {
 #if !CLANG_CHECK_VERSION(3,6)
 	/* disabled on clang due to -Wtautological-pointer-compare */
 	assert(uri != nullptr);
-	assert(db != nullptr);
 #endif
+	assert(db != nullptr);
 	assert(*uri != 0);
 
 	ScopeDatabaseLock protect;
@@ -411,7 +411,7 @@ SimpleDatabase::Mount(const char *uri, Database *db)
 				    "Parent not found");
 
 	Directory *mnt = r.directory->CreateChild(r.uri);
-	mnt->mounted_database = db;
+	mnt->mounted_database = std::move(db);
 }
 
 static constexpr bool
@@ -441,27 +441,21 @@ SimpleDatabase::Mount(const char *local_uri, const char *storage_uri)
 #ifndef ENABLE_ZLIB
 	constexpr bool compress = false;
 #endif
-	auto db = new SimpleDatabase(cache_path / name_fs,
-				     compress);
-	try {
-		db->Open();
-	} catch (...) {
-		delete db;
-		throw;
-	}
+	auto db = std::make_unique<SimpleDatabase>(cache_path / name_fs,
+						   compress);
+	db->Open();
 
 	// TODO: update the new database instance?
 
 	try {
-		Mount(local_uri, db);
+		Mount(local_uri, std::move(db));
 	} catch (...) {
 		db->Close();
-		delete db;
 		throw;
 	}
 }
 
-inline Database *
+inline DatabasePtr
 SimpleDatabase::LockUmountSteal(const char *uri) noexcept
 {
 	ScopeDatabaseLock protect;
@@ -470,8 +464,7 @@ SimpleDatabase::LockUmountSteal(const char *uri) noexcept
 	if (r.uri != nullptr || !r.directory->IsMount())
 		return nullptr;
 
-	Database *db = r.directory->mounted_database;
-	r.directory->mounted_database = nullptr;
+	auto db = std::move(r.directory->mounted_database);
 	r.directory->Delete();
 
 	return db;
@@ -480,12 +473,11 @@ SimpleDatabase::LockUmountSteal(const char *uri) noexcept
 bool
 SimpleDatabase::Unmount(const char *uri) noexcept
 {
-	Database *db = LockUmountSteal(uri);
+	auto db = LockUmountSteal(uri);
 	if (db == nullptr)
 		return false;
 
 	db->Close();
-	delete db;
 	return true;
 }
 

src/db/plugins/simple/SimpleDatabasePlugin.hxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -21,6 +21,7 @@
 #define MPD_SIMPLE_DATABASE_PLUGIN_HXX
 
 #include "db/Interface.hxx"
+#include "db/Ptr.hxx"
 #include "fs/AllocatedPath.hxx"
 #include "song/LightSong.hxx"
 #include "util/Manual.hxx"
@@ -68,15 +69,14 @@ class SimpleDatabase : public Database {
 	mutable unsigned borrowed_song_count;
 #endif
 
+public:
 	SimpleDatabase(const ConfigBlock &block);
-
 	SimpleDatabase(AllocatedPath &&_path, bool _compress) noexcept;
 
-public:
-	static Database *Create(EventLoop &main_event_loop,
-				EventLoop &io_event_loop,
-				DatabaseListener &listener,
-				const ConfigBlock &block);
+	static DatabasePtr Create(EventLoop &main_event_loop,
+				  EventLoop &io_event_loop,
+				  DatabaseListener &listener,
+				  const ConfigBlock &block);
 
 	gcc_pure
 	Directory &GetRoot() noexcept {
@@ -99,7 +99,7 @@ public:
 	 * success, this object gains ownership of the given #Database
 	 */
 	gcc_nonnull_all
-	void Mount(const char *uri, Database *db);
+	void Mount(const char *uri, DatabasePtr db);
 
 	/**
 	 * Throws #std::runtime_error on error.
@@ -142,7 +142,7 @@ private:
 	 */
 	void Load();
 
-	Database *LockUmountSteal(const char *uri) noexcept;
+	DatabasePtr LockUmountSteal(const char *uri) noexcept;
 };
 
 extern const DatabasePlugin simple_db_plugin;

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2018 The Music Player Daemon Project
+ * Copyright 2003-2019 The Music Player Daemon Project
  * http://www.musicpd.org
  *
  * This program is free software; you can redistribute it and/or modify
@@ -82,10 +82,10 @@ public:
 		:Database(upnp_db_plugin),
 		 event_loop(_event_loop) {}
 
-	static Database *Create(EventLoop &main_event_loop,
-				EventLoop &io_event_loop,
-				DatabaseListener &listener,
-				const ConfigBlock &block) noexcept;
+	static DatabasePtr Create(EventLoop &main_event_loop,
+				  EventLoop &io_event_loop,
+				  DatabaseListener &listener,
+				  const ConfigBlock &block) noexcept;
 
 	void Open() override;
 	void Close() noexcept override;
@@ -146,12 +146,12 @@ private:
 			      const UPnPDirObject& dirent) const;
 };
 
-Database *
+DatabasePtr
 UpnpDatabase::Create(EventLoop &, EventLoop &io_event_loop,
 		     gcc_unused DatabaseListener &listener,
 		     const ConfigBlock &) noexcept
 {
-	return new UpnpDatabase(io_event_loop);
+	return std::make_unique<UpnpDatabase>(io_event_loop);
 }
 
 void