storage: add struct StoragePlugin and a plugin registry

Makefile.am

@@ -425,6 +425,8 @@ if ENABLE_DATABASE
 noinst_LIBRARIES += libstorage.a
 
 libstorage_a_SOURCES = \
+	src/storage/StoragePlugin.hxx \
+	src/storage/Registry.cxx src/storage/Registry.hxx \
 	src/storage/StorageInterface.cxx src/storage/StorageInterface.hxx \
 	src/storage/plugins/LocalStorage.cxx src/storage/plugins/LocalStorage.hxx \
 	src/storage/FileInfo.hxx

src/CommandLine.cxx

@@ -43,6 +43,8 @@
 #ifdef ENABLE_DATABASE
 #include "db/Registry.hxx"
 #include "db/DatabasePlugin.hxx"
+#include "storage/Registry.hxx"
+#include "storage/StoragePlugin.hxx"
 #endif
 
 #ifdef ENABLE_NEIGHBOR_PLUGINS
@@ -113,6 +115,12 @@ static void version(void)
 
 	for (auto i = database_plugins; *i != nullptr; ++i)
 		printf(" %s", (*i)->name);
+
+	puts("\n\n"
+	     "Storage plugins:");
+
+	for (auto i = storage_plugins; *i != nullptr; ++i)
+		printf(" %s", (*i)->name);
 #endif
 
 #ifdef ENABLE_NEIGHBOR_PLUGINS

src/storage/Registry.cxx

+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "Registry.hxx"
+#include "StoragePlugin.hxx"
+#include "plugins/LocalStorage.hxx"
+#include "plugins/SmbclientStorage.hxx"
+#include "util/Error.hxx"
+
+#include <assert.h>
+#include <string.h>
+
+const StoragePlugin *const storage_plugins[] = {
+	&local_storage_plugin,
+#ifdef ENABLE_SMBCLIENT
+	&smbclient_storage_plugin,
+#endif
+	nullptr
+};
+
+const StoragePlugin *
+GetStoragePluginByName(const char *name)
+{
+	for (auto i = storage_plugins; *i != nullptr; ++i) {
+		const StoragePlugin &plugin = **i;
+		if (strcmp(plugin.name, name) == 0)
+			return *i;
+	}
+
+	return nullptr;
+}
+
+Storage *
+CreateStorageURI(const char *uri, Error &error)
+{
+	assert(!error.IsDefined());
+
+	for (auto i = storage_plugins; *i != nullptr; ++i) {
+		const StoragePlugin &plugin = **i;
+
+		if (plugin.create_uri == nullptr)
+			continue;
+
+		Storage *storage = plugin.create_uri(uri, error);
+		if (storage != nullptr || error.IsDefined())
+			return storage;
+	}
+
+	return nullptr;
+}

src/storage/Registry.hxx

+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_STORAGE_REGISTRY_HXX
+#define MPD_STORAGE_REGISTRY_HXX
+
+#include "check.h"
+#include "Compiler.h"
+
+struct StoragePlugin;
+class Storage;
+class Error;
+
+/**
+ * nullptr terminated list of all storage plugins which were enabled at
+ * compile time.
+ */
+extern const StoragePlugin *const storage_plugins[];
+
+gcc_nonnull_all gcc_pure
+const StoragePlugin *
+GetStoragePluginByName(const char *name);
+
+gcc_nonnull_all gcc_malloc
+Storage *
+CreateStorageURI(const char *uri, Error &error);
+
+#endif

src/storage/StoragePlugin.hxx

+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_STORAGE_PLUGIN_HXX
+#define MPD_STORAGE_PLUGIN_HXX
+
+#include "check.h"
+
+class Error;
+class Storage;
+
+struct StoragePlugin {
+	const char *name;
+
+	Storage *(*create_uri)(const char *uri, Error &error);
+};
+
+#endif

src/storage/plugins/LocalStorage.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "LocalStorage.hxx"
+#include "storage/StoragePlugin.hxx"
 #include "storage/StorageInterface.hxx"
 #include "storage/FileInfo.hxx"
 #include "util/Error.hxx"
@@ -210,3 +211,8 @@ CreateLocalStorage(Path base_fs)
 {
 	return new LocalStorage(base_fs);
 }
+
+const StoragePlugin local_storage_plugin = {
+	"local",
+	nullptr,
+};

src/storage/plugins/LocalStorage.hxx

@@ -23,9 +23,12 @@
 #include "check.h"
 #include "Compiler.h"
 
+struct StoragePlugin;
 class Storage;
 class Path;
 
+extern const StoragePlugin local_storage_plugin;
+
 gcc_malloc gcc_nonnull_all
 Storage *
 CreateLocalStorage(Path base_fs);

src/storage/plugins/SmbclientStorage.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "SmbclientStorage.hxx"
+#include "storage/StoragePlugin.hxx"
 #include "storage/StorageInterface.hxx"
 #include "storage/FileInfo.hxx"
 #include "lib/smbclient/Init.hxx"
@@ -178,9 +179,12 @@ SmbclientDirectoryReader::GetInfo(gcc_unused bool follow, FileInfo &info,
 	return ::GetInfo(path.c_str(), info, error);
 }
 
-Storage *
-CreateSmbclientStorage(const char *base, Error &error)
+static Storage *
+CreateSmbclientStorageURI(const char *base, Error &error)
 {
+	if (memcmp(base, "smb://", 6) != 0)
+		return nullptr;
+
 	if (!SmbclientInit(error))
 		return nullptr;
 
@@ -200,3 +204,8 @@ CreateSmbclientStorage(const char *base, Error &error)
 
 	return new SmbclientStorage(base, ctx2);
 }
+
+const StoragePlugin smbclient_storage_plugin = {
+	"smbclient",
+	CreateSmbclientStorageURI,
+};

src/storage/plugins/SmbclientStorage.hxx

@@ -22,10 +22,8 @@
 
 #include "check.h"
 
-class Error;
-class Storage;
+struct StoragePlugin;
 
-Storage *
-CreateSmbclientStorage(const char *base, Error &error);
+extern const StoragePlugin smbclient_storage_plugin;
 
 #endif