db/simple: create dedicated directory

12 files changed, 1776 insertions, 0 deletions

diff --git a/src/db/plugins/simple/DatabaseSave.cxx b/src/db/plugins/simple/DatabaseSave.cxx
new file mode 100644
index 000000000..62034a0b8
--- /dev/null
+++ b/src/db/plugins/simple/DatabaseSave.cxx
@@ -0,0 +1,159 @@
+/*
+ * 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 "DatabaseSave.hxx"
+#include "db/DatabaseLock.hxx"
+#include "db/DatabaseError.hxx"
+#include "Directory.hxx"
+#include "DirectorySave.hxx"
+#include "fs/TextFile.hxx"
+#include "tag/Tag.hxx"
+#include "tag/TagSettings.h"
+#include "fs/Charset.hxx"
+#include "util/StringUtil.hxx"
+#include "util/Error.hxx"
+#include "Log.hxx"
+
+#include <string.h>
+#include <stdlib.h>
+
+#define DIRECTORY_INFO_BEGIN "info_begin"
+#define DIRECTORY_INFO_END "info_end"
+#define DB_FORMAT_PREFIX "format: "
+#define DIRECTORY_MPD_VERSION "mpd_version: "
+#define DIRECTORY_FS_CHARSET "fs_charset: "
+#define DB_TAG_PREFIX "tag: "
+
+static constexpr unsigned DB_FORMAT = 2;
+
+/**
+ * The oldest database format understood by this MPD version.
+ */
+static constexpr unsigned OLDEST_DB_FORMAT = 1;
+
+void
+db_save_internal(FILE *fp, const Directory &music_root)
+{
+	fprintf(fp, "%s\n", DIRECTORY_INFO_BEGIN);
+	fprintf(fp, DB_FORMAT_PREFIX "%u\n", DB_FORMAT);
+	fprintf(fp, "%s%s\n", DIRECTORY_MPD_VERSION, VERSION);
+	fprintf(fp, "%s%s\n", DIRECTORY_FS_CHARSET, GetFSCharset());
+
+	for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; ++i)
+		if (!ignore_tag_items[i])
+			fprintf(fp, DB_TAG_PREFIX "%s\n", tag_item_names[i]);
+
+	fprintf(fp, "%s\n", DIRECTORY_INFO_END);
+
+	directory_save(fp, music_root);
+}
+
+bool
+db_load_internal(TextFile &file, Directory &music_root, Error &error)
+{
+	char *line;
+	unsigned format = 0;
+	bool found_charset = false, found_version = false;
+	bool success;
+	bool tags[TAG_NUM_OF_ITEM_TYPES];
+
+	/* get initial info */
+	line = file.ReadLine();
+	if (line == nullptr || strcmp(DIRECTORY_INFO_BEGIN, line) != 0) {
+		error.Set(db_domain, "Database corrupted");
+		return false;
+	}
+
+	memset(tags, false, sizeof(tags));
+
+	while ((line = file.ReadLine()) != nullptr &&
+	       strcmp(line, DIRECTORY_INFO_END) != 0) {
+		if (StringStartsWith(line, DB_FORMAT_PREFIX)) {
+			format = atoi(line + sizeof(DB_FORMAT_PREFIX) - 1);
+		} else if (StringStartsWith(line, DIRECTORY_MPD_VERSION)) {
+			if (found_version) {
+				error.Set(db_domain, "Duplicate version line");
+				return false;
+			}
+
+			found_version = true;
+		} else if (StringStartsWith(line, DIRECTORY_FS_CHARSET)) {
+			const char *new_charset;
+
+			if (found_charset) {
+				error.Set(db_domain, "Duplicate charset line");
+				return false;
+			}
+
+			found_charset = true;
+
+			new_charset = line + sizeof(DIRECTORY_FS_CHARSET) - 1;
+			const char *const old_charset = GetFSCharset();
+			if (*old_charset != 0
+			    && strcmp(new_charset, old_charset) != 0) {
+				error.Format(db_domain,
+					     "Existing database has charset "
+					     "\"%s\" instead of \"%s\"; "
+					     "discarding database file",
+					     new_charset, old_charset);
+				return false;
+			}
+		} else if (StringStartsWith(line, DB_TAG_PREFIX)) {
+			const char *name = line + sizeof(DB_TAG_PREFIX) - 1;
+			TagType tag = tag_name_parse(name);
+			if (tag == TAG_NUM_OF_ITEM_TYPES) {
+				error.Format(db_domain,
+					     "Unrecognized tag '%s', "
+					     "discarding database file",
+					     name);
+				return false;
+			}
+
+			tags[tag] = true;
+		} else {
+			error.Format(db_domain, "Malformed line: %s", line);
+			return false;
+		}
+	}
+
+	if (format < OLDEST_DB_FORMAT || format > DB_FORMAT) {
+		error.Set(db_domain,
+			  "Database format mismatch, "
+			  "discarding database file");
+		return false;
+	}
+
+	for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; ++i) {
+		if (!ignore_tag_items[i] && !tags[i]) {
+			error.Set(db_domain,
+				  "Tag list mismatch, "
+				  "discarding database file");
+			return false;
+		}
+	}
+
+	LogDebug(db_domain, "reading DB");
+
+	db_lock();
+	success = directory_load(file, music_root, error);
+	db_unlock();
+
+	return success;
+}
diff --git a/src/db/plugins/simple/DatabaseSave.hxx b/src/db/plugins/simple/DatabaseSave.hxx
new file mode 100644
index 000000000..3bd3377ae
--- /dev/null
+++ b/src/db/plugins/simple/DatabaseSave.hxx
@@ -0,0 +1,35 @@
+/*
+ * 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_DATABASE_SAVE_HXX
+#define MPD_DATABASE_SAVE_HXX
+
+#include <stdio.h>
+
+struct Directory;
+class TextFile;
+class Error;
+
+void
+db_save_internal(FILE *file, const Directory &root);
+
+bool
+db_load_internal(TextFile &file, Directory &root, Error &error);
+
+#endif
diff --git a/src/db/plugins/simple/Directory.cxx b/src/db/plugins/simple/Directory.cxx
new file mode 100644
index 000000000..98262bc52
--- /dev/null
+++ b/src/db/plugins/simple/Directory.cxx
@@ -0,0 +1,291 @@
+/*
+ * 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 "Directory.hxx"
+#include "SongSort.hxx"
+#include "Song.hxx"
+#include "db/LightDirectory.hxx"
+#include "db/LightSong.hxx"
+#include "db/Uri.hxx"
+#include "db/DatabaseLock.hxx"
+#include "SongFilter.hxx"
+#include "lib/icu/Collate.hxx"
+#include "fs/Traits.hxx"
+#include "util/Alloc.hxx"
+#include "util/Error.hxx"
+
+extern "C" {
+#include "util/list_sort.h"
+}
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+Directory::Directory(std::string &&_path_utf8, Directory *_parent)
+	:parent(_parent),
+	 mtime(0), have_stat(false),
+	 path(std::move(_path_utf8))
+{
+	INIT_LIST_HEAD(&children);
+	INIT_LIST_HEAD(&songs);
+}
+
+Directory::~Directory()
+{
+	Song *song, *ns;
+	directory_for_each_song_safe(song, ns, *this)
+		song->Free();
+
+	Directory *child, *n;
+	directory_for_each_child_safe(child, n, *this)
+		delete child;
+}
+
+void
+Directory::Delete()
+{
+	assert(holding_db_lock());
+	assert(parent != nullptr);
+
+	list_del(&siblings);
+	delete this;
+}
+
+const char *
+Directory::GetName() const
+{
+	assert(!IsRoot());
+
+	return PathTraitsUTF8::GetBase(path.c_str());
+}
+
+Directory *
+Directory::CreateChild(const char *name_utf8)
+{
+	assert(holding_db_lock());
+	assert(name_utf8 != nullptr);
+	assert(*name_utf8 != 0);
+
+	std::string path_utf8 = IsRoot()
+		? std::string(name_utf8)
+		: PathTraitsUTF8::Build(GetPath(), name_utf8);
+
+	Directory *child = new Directory(std::move(path_utf8), this);
+	list_add_tail(&child->siblings, &children);
+	return child;
+}
+
+const Directory *
+Directory::FindChild(const char *name) const
+{
+	assert(holding_db_lock());
+
+	const Directory *child;
+	directory_for_each_child(child, *this)
+		if (strcmp(child->GetName(), name) == 0)
+			return child;
+
+	return nullptr;
+}
+
+void
+Directory::PruneEmpty()
+{
+	assert(holding_db_lock());
+
+	Directory *child, *n;
+	directory_for_each_child_safe(child, n, *this) {
+		child->PruneEmpty();
+
+		if (child->IsEmpty())
+			child->Delete();
+	}
+}
+
+Directory *
+Directory::LookupDirectory(const char *uri)
+{
+	assert(holding_db_lock());
+	assert(uri != nullptr);
+
+	if (isRootDirectory(uri))
+		return this;
+
+	char *duplicated = xstrdup(uri), *name = duplicated;
+
+	Directory *d = this;
+	while (1) {
+		char *slash = strchr(name, '/');
+		if (slash == name) {
+			d = nullptr;
+			break;
+		}
+
+		if (slash != nullptr)
+			*slash = '\0';
+
+		d = d->FindChild(name);
+		if (d == nullptr || slash == nullptr)
+			break;
+
+		name = slash + 1;
+	}
+
+	free(duplicated);
+
+	return d;
+}
+
+void
+Directory::AddSong(Song *song)
+{
+	assert(holding_db_lock());
+	assert(song != nullptr);
+	assert(song->parent == this);
+
+	list_add_tail(&song->siblings, &songs);
+}
+
+void
+Directory::RemoveSong(Song *song)
+{
+	assert(holding_db_lock());
+	assert(song != nullptr);
+	assert(song->parent == this);
+
+	list_del(&song->siblings);
+}
+
+const Song *
+Directory::FindSong(const char *name_utf8) const
+{
+	assert(holding_db_lock());
+	assert(name_utf8 != nullptr);
+
+	Song *song;
+	directory_for_each_song(song, *this) {
+		assert(song->parent == this);
+
+		if (strcmp(song->uri, name_utf8) == 0)
+			return song;
+	}
+
+	return nullptr;
+}
+
+Song *
+Directory::LookupSong(const char *uri)
+{
+	char *duplicated, *base;
+
+	assert(holding_db_lock());
+	assert(uri != nullptr);
+
+	duplicated = xstrdup(uri);
+	base = strrchr(duplicated, '/');
+
+	Directory *d = this;
+	if (base != nullptr) {
+		*base++ = 0;
+		d = d->LookupDirectory(duplicated);
+		if (d == nullptr) {
+			free(duplicated);
+			return nullptr;
+		}
+	} else
+		base = duplicated;
+
+	Song *song = d->FindSong(base);
+	assert(song == nullptr || song->parent == d);
+
+	free(duplicated);
+	return song;
+
+}
+
+static int
+directory_cmp(gcc_unused void *priv,
+	      struct list_head *_a, struct list_head *_b)
+{
+	const Directory *a = (const Directory *)_a;
+	const Directory *b = (const Directory *)_b;
+
+	return IcuCollate(a->path.c_str(), b->path.c_str());
+}
+
+void
+Directory::Sort()
+{
+	assert(holding_db_lock());
+
+	list_sort(nullptr, &children, directory_cmp);
+	song_list_sort(&songs);
+
+	Directory *child;
+	directory_for_each_child(child, *this)
+		child->Sort();
+}
+
+bool
+Directory::Walk(bool recursive, const SongFilter *filter,
+		VisitDirectory visit_directory, VisitSong visit_song,
+		VisitPlaylist visit_playlist,
+		Error &error) const
+{
+	assert(!error.IsDefined());
+
+	if (visit_song) {
+		Song *song;
+		directory_for_each_song(song, *this) {
+			const LightSong song2 = song->Export();
+			if ((filter == nullptr || filter->Match(song2)) &&
+			    !visit_song(song2, error))
+				return false;
+		}
+	}
+
+	if (visit_playlist) {
+		for (const PlaylistInfo &p : playlists)
+			if (!visit_playlist(p, Export(), error))
+				return false;
+	}
+
+	Directory *child;
+	directory_for_each_child(child, *this) {
+		if (visit_directory &&
+		    !visit_directory(child->Export(), error))
+			return false;
+
+		if (recursive &&
+		    !child->Walk(recursive, filter,
+				 visit_directory, visit_song, visit_playlist,
+				 error))
+			return false;
+	}
+
+	return true;
+}
+
+LightDirectory
+Directory::Export() const
+{
+	return LightDirectory(GetPath(), mtime);
+}
diff --git a/src/db/plugins/simple/Directory.hxx b/src/db/plugins/simple/Directory.hxx
new file mode 100644
index 000000000..6c60b7ebf
--- /dev/null
+++ b/src/db/plugins/simple/Directory.hxx
@@ -0,0 +1,239 @@
+/*
+ * 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_DIRECTORY_HXX
+#define MPD_DIRECTORY_HXX
+
+#include "check.h"
+#include "util/list.h"
+#include "Compiler.h"
+#include "db/Visitor.hxx"
+#include "db/PlaylistVector.hxx"
+
+#include <string>
+
+static constexpr unsigned DEVICE_INARCHIVE = -1;
+static constexpr unsigned DEVICE_CONTAINER = -2;
+
+#define directory_for_each_child(pos, directory) \
+	list_for_each_entry(pos, &(directory).children, siblings)
+
+#define directory_for_each_child_safe(pos, n, directory) \
+	list_for_each_entry_safe(pos, n, &(directory).children, siblings)
+
+#define directory_for_each_song(pos, directory) \
+	list_for_each_entry(pos, &(directory).songs, siblings)
+
+#define directory_for_each_song_safe(pos, n, directory) \
+	list_for_each_entry_safe(pos, n, &(directory).songs, siblings)
+
+struct Song;
+struct db_visitor;
+class SongFilter;
+class Error;
+
+struct Directory {
+	/**
+	 * Pointers to the siblings of this directory within the
+	 * parent directory.  It is unused (undefined) in the root
+	 * directory.
+	 *
+	 * This attribute is protected with the global #db_mutex.
+	 * Read access in the update thread does not need protection.
+	 */
+	struct list_head siblings;
+
+	/**
+	 * A doubly linked list of child directories.
+	 *
+	 * This attribute is protected with the global #db_mutex.
+	 * Read access in the update thread does not need protection.
+	 */
+	struct list_head children;
+
+	/**
+	 * A doubly linked list of songs within this directory.
+	 *
+	 * This attribute is protected with the global #db_mutex.
+	 * Read access in the update thread does not need protection.
+	 */
+	struct list_head songs;
+
+	PlaylistVector playlists;
+
+	Directory *parent;
+	time_t mtime;
+	unsigned inode, device;
+	bool have_stat; /* not needed if ino_t == dev_t == 0 is impossible */
+
+	std::string path;
+
+public:
+	Directory(std::string &&_path_utf8, Directory *_parent);
+	~Directory();
+
+	/**
+	 * Create a new root #Directory object.
+	 */
+	gcc_malloc
+	static Directory *NewRoot() {
+		return new Directory(std::string(), nullptr);
+	}
+
+	/**
+	 * Remove this #Directory object from its parent and free it.  This
+	 * must not be called with the root Directory.
+	 *
+	 * Caller must lock the #db_mutex.
+	 */
+	void Delete();
+
+	/**
+	 * Create a new #Directory object as a child of the given one.
+	 *
+	 * Caller must lock the #db_mutex.
+	 *
+	 * @param name_utf8 the UTF-8 encoded name of the new sub directory
+	 */
+	gcc_malloc
+	Directory *CreateChild(const char *name_utf8);
+
+	/**
+	 * Caller must lock the #db_mutex.
+	 */
+	gcc_pure
+	const Directory *FindChild(const char *name) const;
+
+	gcc_pure
+	Directory *FindChild(const char *name) {
+		const Directory *cthis = this;
+		return const_cast<Directory *>(cthis->FindChild(name));
+	}
+
+	/**
+	 * Look up a sub directory, and create the object if it does not
+	 * exist.
+	 *
+	 * Caller must lock the #db_mutex.
+	 */
+	Directory *MakeChild(const char *name_utf8) {
+		Directory *child = FindChild(name_utf8);
+		if (child == nullptr)
+			child = CreateChild(name_utf8);
+		return child;
+	}
+
+	/**
+	 * Looks up a directory by its relative URI.
+	 *
+	 * @param uri the relative URI
+	 * @return the Directory, or nullptr if none was found
+	 */
+	gcc_pure
+	Directory *LookupDirectory(const char *uri);
+
+	gcc_pure
+	bool IsEmpty() const {
+		return list_empty(&children) &&
+			list_empty(&songs) &&
+			playlists.empty();
+	}
+
+	gcc_pure
+	const char *GetPath() const {
+		return path.c_str();
+	}
+
+	/**
+	 * Returns the base name of the directory.
+	 */
+	gcc_pure
+	const char *GetName() const;
+
+	/**
+	 * Is this the root directory of the music database?
+	 */
+	gcc_pure
+	bool IsRoot() const {
+		return parent == nullptr;
+	}
+
+	/**
+	 * Look up a song in this directory by its name.
+	 *
+	 * Caller must lock the #db_mutex.
+	 */
+	gcc_pure
+	const Song *FindSong(const char *name_utf8) const;
+
+	gcc_pure
+	Song *FindSong(const char *name_utf8) {
+		const Directory *cthis = this;
+		return const_cast<Song *>(cthis->FindSong(name_utf8));
+	}
+
+	/**
+	 * Looks up a song by its relative URI.
+	 *
+	 * Caller must lock the #db_mutex.
+	 *
+	 * @param uri the relative URI
+	 * @return the song, or nullptr if none was found
+	 */
+	gcc_pure
+	Song *LookupSong(const char *uri);
+
+	/**
+	 * Add a song object to this directory.  Its "parent" attribute must
+	 * be set already.
+	 */
+	void AddSong(Song *song);
+
+	/**
+	 * Remove a song object from this directory (which effectively
+	 * invalidates the song object, because the "parent" attribute becomes
+	 * stale), but does not free it.
+	 */
+	void RemoveSong(Song *song);
+
+	/**
+	 * Caller must lock the #db_mutex.
+	 */
+	void PruneEmpty();
+
+	/**
+	 * Sort all directory entries recursively.
+	 *
+	 * Caller must lock the #db_mutex.
+	 */
+	void Sort();
+
+	/**
+	 * Caller must lock #db_mutex.
+	 */
+	bool Walk(bool recursive, const SongFilter *match,
+		  VisitDirectory visit_directory, VisitSong visit_song,
+		  VisitPlaylist visit_playlist,
+		  Error &error) const;
+
+	gcc_pure
+	LightDirectory Export() const;
+};
+
+#endif
diff --git a/src/db/plugins/simple/DirectorySave.cxx b/src/db/plugins/simple/DirectorySave.cxx
new file mode 100644
index 000000000..6cc5df6cb
--- /dev/null
+++ b/src/db/plugins/simple/DirectorySave.cxx
@@ -0,0 +1,207 @@
+/*
+ * 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 "DirectorySave.hxx"
+#include "Directory.hxx"
+#include "Song.hxx"
+#include "SongSave.hxx"
+#include "DetachedSong.hxx"
+#include "PlaylistDatabase.hxx"
+#include "fs/TextFile.hxx"
+#include "util/StringUtil.hxx"
+#include "util/NumberParser.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+
+#include <stddef.h>
+#include <string.h>
+
+#define DIRECTORY_DIR "directory: "
+#define DIRECTORY_TYPE "type: "
+#define DIRECTORY_MTIME "mtime: "
+#define DIRECTORY_BEGIN "begin: "
+#define DIRECTORY_END "end: "
+
+static constexpr Domain directory_domain("directory");
+
+gcc_const
+static const char *
+DeviceToTypeString(unsigned device)
+{
+	switch (device) {
+	case DEVICE_INARCHIVE:
+		return "archive";
+
+	case DEVICE_CONTAINER:
+		return "container";
+
+	default:
+		return nullptr;
+	}
+}
+
+gcc_pure
+static unsigned
+ParseTypeString(const char *type)
+{
+	if (strcmp(type, "archive") == 0)
+		return DEVICE_INARCHIVE;
+	else if (strcmp(type, "container") == 0)
+		return DEVICE_CONTAINER;
+	else
+		return 0;
+}
+
+void
+directory_save(FILE *fp, const Directory &directory)
+{
+	if (!directory.IsRoot()) {
+		const char *type = DeviceToTypeString(directory.device);
+		if (type != nullptr)
+			fprintf(fp, DIRECTORY_TYPE "%s\n", type);
+
+		if (directory.mtime != 0)
+			fprintf(fp, DIRECTORY_MTIME "%lu\n",
+				(unsigned long)directory.mtime);
+
+		fprintf(fp, "%s%s\n", DIRECTORY_BEGIN, directory.GetPath());
+	}
+
+	Directory *cur;
+	directory_for_each_child(cur, directory) {
+		fprintf(fp, DIRECTORY_DIR "%s\n", cur->GetName());
+
+		directory_save(fp, *cur);
+
+		if (ferror(fp))
+			return;
+	}
+
+	Song *song;
+	directory_for_each_song(song, directory)
+		song_save(fp, *song);
+
+	playlist_vector_save(fp, directory.playlists);
+
+	if (!directory.IsRoot())
+		fprintf(fp, DIRECTORY_END "%s\n", directory.GetPath());
+}
+
+static bool
+ParseLine(Directory &directory, const char *line)
+{
+	if (StringStartsWith(line, DIRECTORY_MTIME)) {
+		directory.mtime =
+			ParseUint64(line + sizeof(DIRECTORY_MTIME) - 1);
+	} else if (StringStartsWith(line, DIRECTORY_TYPE)) {
+		directory.device =
+			ParseTypeString(line + sizeof(DIRECTORY_TYPE) - 1);
+	} else
+		return false;
+
+	return true;
+}
+
+static Directory *
+directory_load_subdir(TextFile &file, Directory &parent, const char *name,
+		      Error &error)
+{
+	bool success;
+
+	if (parent.FindChild(name) != nullptr) {
+		error.Format(directory_domain,
+			     "Duplicate subdirectory '%s'", name);
+		return nullptr;
+	}
+
+	Directory *directory = parent.CreateChild(name);
+
+	while (true) {
+		const char *line = file.ReadLine();
+		if (line == nullptr) {
+			error.Set(directory_domain, "Unexpected end of file");
+			directory->Delete();
+			return nullptr;
+		}
+
+		if (StringStartsWith(line, DIRECTORY_BEGIN))
+			break;
+
+		if (!ParseLine(*directory, line)) {
+			error.Format(directory_domain,
+				     "Malformed line: %s", line);
+			directory->Delete();
+			return nullptr;
+		}
+	}
+
+	success = directory_load(file, *directory, error);
+	if (!success) {
+		directory->Delete();
+		return nullptr;
+	}
+
+	return directory;
+}
+
+bool
+directory_load(TextFile &file, Directory &directory, Error &error)
+{
+	const char *line;
+
+	while ((line = file.ReadLine()) != nullptr &&
+	       !StringStartsWith(line, DIRECTORY_END)) {
+		if (StringStartsWith(line, DIRECTORY_DIR)) {
+			Directory *subdir =
+				directory_load_subdir(file, directory,
+						      line + sizeof(DIRECTORY_DIR) - 1,
+						      error);
+			if (subdir == nullptr)
+				return false;
+		} else if (StringStartsWith(line, SONG_BEGIN)) {
+			const char *name = line + sizeof(SONG_BEGIN) - 1;
+
+			if (directory.FindSong(name) != nullptr) {
+				error.Format(directory_domain,
+					     "Duplicate song '%s'", name);
+				return false;
+			}
+
+			DetachedSong *song = song_load(file, name, error);
+			if (song == nullptr)
+				return false;
+
+			directory.AddSong(Song::NewFrom(std::move(*song),
+							directory));
+			delete song;
+		} else if (StringStartsWith(line, PLAYLIST_META_BEGIN)) {
+			const char *name = line + sizeof(PLAYLIST_META_BEGIN) - 1;
+			if (!playlist_metadata_load(file, directory.playlists,
+						    name, error))
+				return false;
+		} else {
+			error.Format(directory_domain,
+				     "Malformed line: %s", line);
+			return false;
+		}
+	}
+
+	return true;
+}
diff --git a/src/db/plugins/simple/DirectorySave.hxx b/src/db/plugins/simple/DirectorySave.hxx
new file mode 100644
index 000000000..07e9e158b
--- /dev/null
+++ b/src/db/plugins/simple/DirectorySave.hxx
@@ -0,0 +1,35 @@
+/*
+ * 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_DIRECTORY_SAVE_HXX
+#define MPD_DIRECTORY_SAVE_HXX
+
+#include <stdio.h>
+
+struct Directory;
+class TextFile;
+class Error;
+
+void
+directory_save(FILE *fp, const Directory &directory);
+
+bool
+directory_load(TextFile &file, Directory &directory, Error &error);
+
+#endif
diff --git a/src/db/plugins/simple/SimpleDatabasePlugin.cxx b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
new file mode 100644
index 000000000..9911caa66
--- /dev/null
+++ b/src/db/plugins/simple/SimpleDatabasePlugin.cxx
@@ -0,0 +1,331 @@
+/*
+ * 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 "SimpleDatabasePlugin.hxx"
+#include "db/DatabasePlugin.hxx"
+#include "db/Selection.hxx"
+#include "db/Helpers.hxx"
+#include "db/LightDirectory.hxx"
+#include "Directory.hxx"
+#include "Song.hxx"
+#include "SongFilter.hxx"
+#include "DatabaseSave.hxx"
+#include "db/DatabaseLock.hxx"
+#include "db/DatabaseError.hxx"
+#include "fs/TextFile.hxx"
+#include "config/ConfigData.hxx"
+#include "fs/FileSystem.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+#include "Log.hxx"
+
+#include <errno.h>
+
+static constexpr Domain simple_db_domain("simple_db");
+
+inline SimpleDatabase::SimpleDatabase()
+	:Database(simple_db_plugin),
+	 path(AllocatedPath::Null()) {}
+
+Database *
+SimpleDatabase::Create(gcc_unused EventLoop &loop,
+		       gcc_unused DatabaseListener &listener,
+		       const config_param &param, Error &error)
+{
+	SimpleDatabase *db = new SimpleDatabase();
+	if (!db->Configure(param, error)) {
+		delete db;
+		db = nullptr;
+	}
+
+	return db;
+}
+
+bool
+SimpleDatabase::Configure(const config_param &param, Error &error)
+{
+	path = param.GetBlockPath("path", error);
+	if (path.IsNull()) {
+		if (!error.IsDefined())
+			error.Set(simple_db_domain,
+				  "No \"path\" parameter specified");
+		return false;
+	}
+
+	path_utf8 = path.ToUTF8();
+
+	return true;
+}
+
+bool
+SimpleDatabase::Check(Error &error) const
+{
+	assert(!path.IsNull());
+
+	/* Check if the file exists */
+	if (!CheckAccess(path)) {
+		/* If the file doesn't exist, we can't check if we can write
+		 * it, so we are going to try to get the directory path, and
+		 * see if we can write a file in that */
+		const auto dirPath = path.GetDirectoryName();
+
+		/* Check that the parent part of the path is a directory */
+		struct stat st;
+		if (!StatFile(dirPath, st)) {
+			error.FormatErrno("Couldn't stat parent directory of db file "
+					  "\"%s\"",
+					  path_utf8.c_str());
+			return false;
+		}
+
+		if (!S_ISDIR(st.st_mode)) {
+			error.Format(simple_db_domain,
+				     "Couldn't create db file \"%s\" because the "
+				     "parent path is not a directory",
+				     path_utf8.c_str());
+			return false;
+		}
+
+#ifndef WIN32
+		/* Check if we can write to the directory */
+		if (!CheckAccess(dirPath, X_OK | W_OK)) {
+			const int e = errno;
+			const std::string dirPath_utf8 = dirPath.ToUTF8();
+			error.FormatErrno(e, "Can't create db file in \"%s\"",
+					  dirPath_utf8.c_str());
+			return false;
+		}
+#endif
+		return true;
+	}
+
+	/* Path exists, now check if it's a regular file */
+	struct stat st;
+	if (!StatFile(path, st)) {
+		error.FormatErrno("Couldn't stat db file \"%s\"",
+				  path_utf8.c_str());
+		return false;
+	}
+
+	if (!S_ISREG(st.st_mode)) {
+		error.Format(simple_db_domain,
+			     "db file \"%s\" is not a regular file",
+			     path_utf8.c_str());
+		return false;
+	}
+
+#ifndef WIN32
+	/* And check that we can write to it */
+	if (!CheckAccess(path, R_OK | W_OK)) {
+		error.FormatErrno("Can't open db file \"%s\" for reading/writing",
+				  path_utf8.c_str());
+		return false;
+	}
+#endif
+
+	return true;
+}
+
+bool
+SimpleDatabase::Load(Error &error)
+{
+	assert(!path.IsNull());
+	assert(root != nullptr);
+
+	TextFile file(path);
+	if (file.HasFailed()) {
+		error.FormatErrno("Failed to open database file \"%s\"",
+				  path_utf8.c_str());
+		return false;
+	}
+
+	if (!db_load_internal(file, *root, error))
+		return false;
+
+	struct stat st;
+	if (StatFile(path, st))
+		mtime = st.st_mtime;
+
+	return true;
+}
+
+bool
+SimpleDatabase::Open(Error &error)
+{
+	root = Directory::NewRoot();
+	mtime = 0;
+
+#ifndef NDEBUG
+	borrowed_song_count = 0;
+#endif
+
+	if (!Load(error)) {
+		delete root;
+
+		LogError(error);
+		error.Clear();
+
+		if (!Check(error))
+			return false;
+
+		root = Directory::NewRoot();
+	}
+
+	return true;
+}
+
+void
+SimpleDatabase::Close()
+{
+	assert(root != nullptr);
+	assert(borrowed_song_count == 0);
+
+	delete root;
+}
+
+const LightSong *
+SimpleDatabase::GetSong(const char *uri, Error &error) const
+{
+	assert(root != nullptr);
+	assert(borrowed_song_count == 0);
+
+	db_lock();
+	const Song *song = root->LookupSong(uri);
+	db_unlock();
+	if (song == nullptr) {
+		error.Format(db_domain, DB_NOT_FOUND,
+			     "No such song: %s", uri);
+		return nullptr;
+	}
+
+	light_song = song->Export();
+
+#ifndef NDEBUG
+	++borrowed_song_count;
+#endif
+
+	return &light_song;
+}
+
+void
+SimpleDatabase::ReturnSong(gcc_unused const LightSong *song) const
+{
+	assert(song == &light_song);
+
+#ifndef NDEBUG
+	assert(borrowed_song_count > 0);
+	--borrowed_song_count;
+#endif
+}
+
+bool
+SimpleDatabase::Visit(const DatabaseSelection &selection,
+		      VisitDirectory visit_directory,
+		      VisitSong visit_song,
+		      VisitPlaylist visit_playlist,
+		      Error &error) const
+{
+	ScopeDatabaseLock protect;
+
+	const Directory *directory = root->LookupDirectory(selection.uri.c_str());
+	if (directory == nullptr) {
+		if (visit_song) {
+			Song *song = root->LookupSong(selection.uri.c_str());
+			if (song != nullptr) {
+				const LightSong song2 = song->Export();
+				return !selection.Match(song2) ||
+					visit_song(song2, error);
+			}
+		}
+
+		error.Set(db_domain, DB_NOT_FOUND, "No such directory");
+		return false;
+	}
+
+	if (selection.recursive && visit_directory &&
+	    !visit_directory(directory->Export(), error))
+		return false;
+
+	return directory->Walk(selection.recursive, selection.filter,
+			       visit_directory, visit_song, visit_playlist,
+			       error);
+}
+
+bool
+SimpleDatabase::VisitUniqueTags(const DatabaseSelection &selection,
+				TagType tag_type,
+				VisitString visit_string,
+				Error &error) const
+{
+	return ::VisitUniqueTags(*this, selection, tag_type, visit_string,
+				 error);
+}
+
+bool
+SimpleDatabase::GetStats(const DatabaseSelection &selection,
+			 DatabaseStats &stats, Error &error) const
+{
+	return ::GetStats(*this, selection, stats, error);
+}
+
+bool
+SimpleDatabase::Save(Error &error)
+{
+	db_lock();
+
+	LogDebug(simple_db_domain, "removing empty directories from DB");
+	root->PruneEmpty();
+
+	LogDebug(simple_db_domain, "sorting DB");
+	root->Sort();
+
+	db_unlock();
+
+	LogDebug(simple_db_domain, "writing DB");
+
+	FILE *fp = FOpen(path, FOpenMode::WriteText);
+	if (!fp) {
+		error.FormatErrno("unable to write to db file \"%s\"",
+				  path_utf8.c_str());
+		return false;
+	}
+
+	db_save_internal(fp, *root);
+
+	if (ferror(fp)) {
+		error.SetErrno("Failed to write to database file");
+		fclose(fp);
+		return false;
+	}
+
+	fclose(fp);
+
+	struct stat st;
+	if (StatFile(path, st))
+		mtime = st.st_mtime;
+
+	return true;
+}
+
+const DatabasePlugin simple_db_plugin = {
+	"simple",
+	DatabasePlugin::FLAG_REQUIRE_STORAGE,
+	SimpleDatabase::Create,
+};
diff --git a/src/db/plugins/simple/SimpleDatabasePlugin.hxx b/src/db/plugins/simple/SimpleDatabasePlugin.hxx
new file mode 100644
index 000000000..40d870460
--- /dev/null
+++ b/src/db/plugins/simple/SimpleDatabasePlugin.hxx
@@ -0,0 +1,114 @@
+/*
+ * 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_SIMPLE_DATABASE_PLUGIN_HXX
+#define MPD_SIMPLE_DATABASE_PLUGIN_HXX
+
+#include "db/Interface.hxx"
+#include "fs/AllocatedPath.hxx"
+#include "db/LightSong.hxx"
+#include "Compiler.h"
+
+#include <cassert>
+
+struct config_param;
+struct Directory;
+struct DatabasePlugin;
+class EventLoop;
+class DatabaseListener;
+
+class SimpleDatabase : public Database {
+	AllocatedPath path;
+	std::string path_utf8;
+
+	Directory *root;
+
+	time_t mtime;
+
+	/**
+	 * A buffer for GetSong().
+	 */
+	mutable LightSong light_song;
+
+#ifndef NDEBUG
+	mutable unsigned borrowed_song_count;
+#endif
+
+	SimpleDatabase();
+
+public:
+	static Database *Create(EventLoop &loop, DatabaseListener &listener,
+				const config_param &param,
+				Error &error);
+
+	gcc_pure
+	Directory *GetRoot() {
+		assert(root != NULL);
+
+		return root;
+	}
+
+	bool Save(Error &error);
+
+	/**
+	 * Returns true if there is a valid database file on the disk.
+	 */
+	bool FileExists() const {
+		return mtime > 0;
+	}
+
+	/* virtual methods from class Database */
+	virtual bool Open(Error &error) override;
+	virtual void Close() override;
+
+	virtual const LightSong *GetSong(const char *uri_utf8,
+					 Error &error) const override;
+	virtual void ReturnSong(const LightSong *song) const;
+
+	virtual bool Visit(const DatabaseSelection &selection,
+			   VisitDirectory visit_directory,
+			   VisitSong visit_song,
+			   VisitPlaylist visit_playlist,
+			   Error &error) const override;
+
+	virtual bool VisitUniqueTags(const DatabaseSelection &selection,
+				     TagType tag_type,
+				     VisitString visit_string,
+				     Error &error) const override;
+
+	virtual bool GetStats(const DatabaseSelection &selection,
+			      DatabaseStats &stats,
+			      Error &error) const override;
+
+	virtual time_t GetUpdateStamp() const override {
+		return mtime;
+	}
+
+private:
+	bool Configure(const config_param &param, Error &error);
+
+	gcc_pure
+	bool Check(Error &error) const;
+
+	bool Load(Error &error);
+};
+
+extern const DatabasePlugin simple_db_plugin;
+
+#endif
diff --git a/src/db/plugins/simple/Song.cxx b/src/db/plugins/simple/Song.cxx
new file mode 100644
index 000000000..3bd3d8316
--- /dev/null
+++ b/src/db/plugins/simple/Song.cxx
@@ -0,0 +1,111 @@
+/*
+ * 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 "Song.hxx"
+#include "Directory.hxx"
+#include "tag/Tag.hxx"
+#include "util/VarSize.hxx"
+#include "DetachedSong.hxx"
+#include "db/LightSong.hxx"
+
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+
+inline Song::Song(const char *_uri, size_t uri_length, Directory &_parent)
+	:parent(&_parent), mtime(0), start_ms(0), end_ms(0)
+{
+	memcpy(uri, _uri, uri_length + 1);
+}
+
+inline Song::~Song()
+{
+}
+
+static Song *
+song_alloc(const char *uri, Directory &parent)
+{
+	size_t uri_length;
+
+	assert(uri);
+	uri_length = strlen(uri);
+	assert(uri_length);
+
+	return NewVarSize<Song>(sizeof(Song::uri),
+				uri_length + 1,
+				uri, uri_length, parent);
+}
+
+Song *
+Song::NewFrom(DetachedSong &&other, Directory &parent)
+{
+	Song *song = song_alloc(other.GetURI(), parent);
+	song->tag = std::move(other.WritableTag());
+	song->mtime = other.GetLastModified();
+	song->start_ms = other.GetStartMS();
+	song->end_ms = other.GetEndMS();
+	return song;
+}
+
+Song *
+Song::NewFile(const char *path, Directory &parent)
+{
+	return song_alloc(path, parent);
+}
+
+void
+Song::Free()
+{
+	DeleteVarSize(this);
+}
+
+std::string
+Song::GetURI() const
+{
+	assert(*uri);
+
+	if (parent->IsRoot())
+		return std::string(uri);
+	else {
+		const char *path = parent->GetPath();
+
+		std::string result;
+		result.reserve(strlen(path) + 1 + strlen(uri));
+		result.assign(path);
+		result.push_back('/');
+		result.append(uri);
+		return result;
+	}
+}
+
+LightSong
+Song::Export() const
+{
+	LightSong dest;
+	dest.directory = parent->IsRoot()
+		? nullptr : parent->GetPath();
+	dest.uri = uri;
+	dest.real_uri = nullptr;
+	dest.tag = &tag;
+	dest.mtime = mtime;
+	dest.start_ms = start_ms;
+	dest.end_ms = end_ms;
+	return dest;
+}
diff --git a/src/db/plugins/simple/Song.hxx b/src/db/plugins/simple/Song.hxx
new file mode 100644
index 000000000..75fce20e9
--- /dev/null
+++ b/src/db/plugins/simple/Song.hxx
@@ -0,0 +1,113 @@
+/*
+ * 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_SONG_HXX
+#define MPD_SONG_HXX
+
+#include "util/list.h"
+#include "tag/Tag.hxx"
+#include "Compiler.h"
+
+#include <string>
+
+#include <assert.h>
+#include <time.h>
+
+struct LightSong;
+struct Directory;
+class DetachedSong;
+class Storage;
+
+/**
+ * A song file inside the configured music directory.  Internal
+ * #SimpleDatabase class.
+ */
+struct Song {
+	/**
+	 * Pointers to the siblings of this directory within the
+	 * parent directory.  It is unused (undefined) if this song is
+	 * not in the database.
+	 *
+	 * This attribute is protected with the global #db_mutex.
+	 * Read access in the update thread does not need protection.
+	 */
+	struct list_head siblings;
+
+	Tag tag;
+
+	/**
+	 * The #Directory that contains this song.  Must be
+	 * non-nullptr.  directory this way.
+	 */
+	Directory *const parent;
+
+	time_t mtime;
+
+	/**
+	 * Start of this sub-song within the file in milliseconds.
+	 */
+	unsigned start_ms;
+
+	/**
+	 * End of this sub-song within the file in milliseconds.
+	 * Unused if zero.
+	 */
+	unsigned end_ms;
+
+	/**
+	 * The file name.
+	 */
+	char uri[sizeof(int)];
+
+	Song(const char *_uri, size_t uri_length, Directory &parent);
+	~Song();
+
+	gcc_malloc
+	static Song *NewFrom(DetachedSong &&other, Directory &parent);
+
+	/** allocate a new song with a local file name */
+	gcc_malloc
+	static Song *NewFile(const char *path_utf8, Directory &parent);
+
+	/**
+	 * allocate a new song structure with a local file name and attempt to
+	 * load its metadata.  If all decoder plugin fail to read its meta
+	 * data, nullptr is returned.
+	 */
+	gcc_malloc
+	static Song *LoadFile(Storage &storage, const char *name_utf8,
+			      Directory &parent);
+
+	void Free();
+
+	bool UpdateFile(Storage &storage);
+	bool UpdateFileInArchive(const Storage &storage);
+
+	/**
+	 * Returns the URI of the song in UTF-8 encoding, including its
+	 * location within the music directory.
+	 */
+	gcc_pure
+	std::string GetURI() const;
+
+	gcc_pure
+	LightSong Export() const;
+};
+
+#endif
diff --git a/src/db/plugins/simple/SongSort.cxx b/src/db/plugins/simple/SongSort.cxx
new file mode 100644
index 000000000..c5752f568
--- /dev/null
+++ b/src/db/plugins/simple/SongSort.cxx
@@ -0,0 +1,113 @@
+/*
+ * 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 "SongSort.hxx"
+#include "Song.hxx"
+#include "tag/Tag.hxx"
+#include "lib/icu/Collate.hxx"
+
+extern "C" {
+#include "util/list_sort.h"
+}
+
+#include <stdlib.h>
+
+static int
+compare_utf8_string(const char *a, const char *b)
+{
+	if (a == nullptr)
+		return b == nullptr ? 0 : -1;
+
+	if (b == nullptr)
+		return 1;
+
+	return IcuCollate(a, b);
+}
+
+/**
+ * Compare two string tag values, ignoring case.  Either one may be
+ * nullptr.
+ */
+static int
+compare_string_tag_item(const Tag &a, const Tag &b,
+			TagType type)
+{
+	return compare_utf8_string(a.GetValue(type),
+				   b.GetValue(type));
+}
+
+/**
+ * Compare two tag values which should contain an integer value
+ * (e.g. disc or track number).  Either one may be nullptr.
+ */
+static int
+compare_number_string(const char *a, const char *b)
+{
+	long ai = a == nullptr ? 0 : strtol(a, nullptr, 10);
+	long bi = b == nullptr ? 0 : strtol(b, nullptr, 10);
+
+	if (ai <= 0)
+		return bi <= 0 ? 0 : -1;
+
+	if (bi <= 0)
+		return 1;
+
+	return ai - bi;
+}
+
+static int
+compare_tag_item(const Tag &a, const Tag &b, TagType type)
+{
+	return compare_number_string(a.GetValue(type),
+				     b.GetValue(type));
+}
+
+/* Only used for sorting/searchin a songvec, not general purpose compares */
+static int
+song_cmp(gcc_unused void *priv, struct list_head *_a, struct list_head *_b)
+{
+	const Song *a = (const Song *)_a;
+	const Song *b = (const Song *)_b;
+	int ret;
+
+	/* first sort by album */
+	ret = compare_string_tag_item(a->tag, b->tag, TAG_ALBUM);
+	if (ret != 0)
+		return ret;
+
+	/* then sort by disc */
+	ret = compare_tag_item(a->tag, b->tag, TAG_DISC);
+	if (ret != 0)
+		return ret;
+
+	/* then by track number */
+	ret = compare_tag_item(a->tag, b->tag, TAG_TRACK);
+	if (ret != 0)
+		return ret;
+
+	/* still no difference?  compare file name */
+	return IcuCollate(a->uri, b->uri);
+}
+
+void
+song_list_sort(struct list_head *songs)
+{
+	list_sort(nullptr, songs, song_cmp);
+}
diff --git a/src/db/plugins/simple/SongSort.hxx b/src/db/plugins/simple/SongSort.hxx
new file mode 100644
index 000000000..28b903532
--- /dev/null
+++ b/src/db/plugins/simple/SongSort.hxx
@@ -0,0 +1,28 @@
+/*
+ * 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_SONG_SORT_HXX
+#define MPD_SONG_SORT_HXX
+
+struct list_head;
+
+void
+song_list_sort(list_head *songs);
+
+#endif