db/Interface: pass std::string_view to GetSong()

src/db/Interface.hxx

@@ -75,7 +75,7 @@ public:
 	 * directory (UTF-8)
 	 * @return a pointer that must be released with ReturnSong()
 	 */
-	virtual const LightSong *GetSong(const char *uri_utf8) const = 0;
+	virtual const LightSong *GetSong(std::string_view uri_utf8) const = 0;
 
 	/**
 	 * Mark the song object as "unused".  Call this on objects

src/db/Uri.hxx

@@ -23,12 +23,6 @@
 #include <string_view>
 
 static inline bool
-isRootDirectory(const char *name)
-{
-	return name[0] == 0 || (name[0] == '/' && name[1] == 0);
-}
-
-static inline bool
 isRootDirectory(std::string_view name) noexcept
 {
 	return name.empty() || (name.size() == 1 && name.front() == '/');

src/db/plugins/ProxyDatabasePlugin.cxx

@@ -121,7 +121,7 @@ public:
 
 	void Open() override;
 	void Close() noexcept override;
-	const LightSong *GetSong(const char *uri_utf8) const override;
+	const LightSong *GetSong(std::string_view uri_utf8) const override;
 	void ReturnSong(const LightSong *song) const noexcept override;
 
 	void Visit(const DatabaseSelection &selection,
@@ -641,12 +641,12 @@ ProxyDatabase::OnIdle() noexcept
 }
 
 const LightSong *
-ProxyDatabase::GetSong(const char *uri) const
+ProxyDatabase::GetSong(std::string_view uri) const
 {
 	// TODO: eliminate the const_cast
 	const_cast<ProxyDatabase *>(this)->EnsureConnected();
 
-	if (!mpd_send_list_meta(connection, uri))
+	if (!mpd_send_list_meta(connection, std::string(uri).c_str()))
 		ThrowError(connection);
 
 	struct mpd_song *song = mpd_recv_song(connection);

src/db/plugins/simple/SimpleDatabasePlugin.cxx

@@ -197,7 +197,7 @@ SimpleDatabase::Close() noexcept
 }
 
 const LightSong *
-SimpleDatabase::GetSong(const char *uri) const
+SimpleDatabase::GetSong(std::string_view uri) const
 {
 	assert(root != nullptr);
 	assert(prefixed_light_song == nullptr);
@@ -211,10 +211,8 @@ SimpleDatabase::GetSong(const char *uri) const
 		/* pass the request to the mounted database */
 		protect.unlock();
 
-		/* note: r.rest.data() is actually null-terminated
-		   because it points inside the "uri" parameter */
 		const LightSong *song =
-			r.directory->mounted_database->GetSong(r.rest.data());
+			r.directory->mounted_database->GetSong(r.rest);
 		if (song == nullptr)
 			return nullptr;
 
@@ -224,7 +222,7 @@ SimpleDatabase::GetSong(const char *uri) const
 		return prefixed_light_song;
 	}
 
-	if (r.rest.data() == nullptr)
+	if (r.rest.empty())
 		/* it's a directory */
 		throw DatabaseError(DatabaseErrorCode::NOT_FOUND,
 				    "No such song");

src/db/plugins/simple/SimpleDatabasePlugin.hxx

@@ -114,7 +114,7 @@ public:
 	void Open() override;
 	void Close() noexcept override;
 
-	const LightSong *GetSong(const char *uri_utf8) const override;
+	const LightSong *GetSong(std::string_view uri_utf8) const override;
 	void ReturnSong(const LightSong *song) const noexcept override;
 
 	void Visit(const DatabaseSelection &selection,

src/db/plugins/upnp/UpnpDatabasePlugin.cxx

@@ -62,8 +62,9 @@ class UpnpSong : UpnpSongData, public LightSong {
 	std::string real_uri2;
 
 public:
-	UpnpSong(UPnPDirObject &&object, std::string &&_uri) noexcept
-		:UpnpSongData(std::move(_uri), std::move(object.tag)),
+	template<typename U>
+	UpnpSong(UPnPDirObject &&object, U &&_uri) noexcept
+		:UpnpSongData(std::forward<U>(_uri), std::move(object.tag)),
 		 LightSong(UpnpSongData::uri.c_str(), UpnpSongData::tag),
 		 real_uri2(std::move(object.url)) {
 		real_uri = real_uri2.c_str();
@@ -87,7 +88,7 @@ public:
 
 	void Open() override;
 	void Close() noexcept override;
-	const LightSong *GetSong(const char *uri_utf8) const override;
+	const LightSong *GetSong(std::string_view uri_utf8) const override;
 	void ReturnSong(const LightSong *song) const noexcept override;
 
 	void Visit(const DatabaseSelection &selection,
@@ -185,7 +186,7 @@ UpnpDatabase::ReturnSong(const LightSong *_song) const noexcept
 // Get song info by path. We can receive either the id path, or the titles
 // one
 const LightSong *
-UpnpDatabase::GetSong(const char *uri) const
+UpnpDatabase::GetSong(std::string_view uri) const
 {
 	auto vpath = SplitString(uri, '/');
 	if (vpath.empty())