Save and restore mountpoints within the state file.

Makefile.am

@@ -702,6 +702,7 @@ libstorage_a_SOURCES = \
 	src/storage/MemoryDirectoryReader.cxx src/storage/MemoryDirectoryReader.hxx \
 	src/storage/Configured.cxx src/storage/Configured.hxx \
 	src/storage/plugins/LocalStorage.cxx src/storage/plugins/LocalStorage.hxx \
+	src/storage/StorageState.cxx src/storage/StorageState.hxx \
 	src/storage/FileInfo.hxx
 
 libstorage_a_CPPFLAGS = $(AM_CPPFLAGS) \

NEWS

@@ -9,6 +9,7 @@ ver 0.20.13 (not yet released)
   - simple: fix "lsinfo" into mount points
   - upnp: work around libupnp 1.6.24 API breakage
 * queue: fix spuriously misplaced prioritized songs
+* save and restore mountpoints within the state file
 * include Windows cross-build script in source tarball
 * fix Windows build failures
 

src/StateFile.cxx

@@ -24,6 +24,7 @@
 #include "fs/io/TextFile.hxx"
 #include "fs/io/FileOutputStream.hxx"
 #include "fs/io/BufferedOutputStream.hxx"
+#include "storage/StorageState.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
 #include "mixer/Volume.hxx"
@@ -56,6 +57,9 @@ StateFile::RememberVersions() noexcept
 	prev_output_version = audio_output_state_get_version();
 	prev_playlist_version = playlist_state_get_hash(partition.playlist,
 							partition.pc);
+#ifdef ENABLE_DATABASE
+	prev_storage_version = storage_state_get_hash(partition.instance);
+#endif
 }
 
 bool
@@ -64,7 +68,11 @@ StateFile::IsModified() const noexcept
 	return prev_volume_version != sw_volume_state_get_hash() ||
 		prev_output_version != audio_output_state_get_version() ||
 		prev_playlist_version != playlist_state_get_hash(partition.playlist,
-								 partition.pc);
+								 partition.pc)
+#ifdef ENABLE_DATABASE
+		|| prev_storage_version != storage_state_get_hash(partition.instance)
+#endif
+		;
 }
 
 inline void
@@ -72,6 +80,11 @@ StateFile::Write(BufferedOutputStream &os)
 {
 	save_sw_volume_state(os);
 	audio_output_state_save(os, partition.outputs);
+
+#ifdef ENABLE_DATABASE
+	storage_state_save(os, partition.instance);
+#endif
+
 	playlist_state_save(os, partition.playlist, partition.pc);
 }
 
@@ -123,6 +136,10 @@ try {
 			playlist_state_restore(line, file, song_loader,
 					       partition.playlist,
 					       partition.pc);
+#ifdef ENABLE_DATABASE
+		success = success || storage_state_restore(line, file, partition.instance);
+#endif
+
 		if (!success)
 			FormatError(state_file_domain,
 				    "Unrecognized line in state file: %s",

src/StateFile.hxx

@@ -46,6 +46,10 @@ class StateFile final : private TimeoutMonitor {
 	unsigned prev_volume_version = 0, prev_output_version = 0,
 		prev_playlist_version = 0;
 
+#ifdef ENABLE_DATABASE
+	unsigned prev_storage_version = 0;
+#endif
+
 public:
 	static constexpr std::chrono::steady_clock::duration DEFAULT_INTERVAL = std::chrono::minutes(2);
 

src/storage/StorageState.cxx

+/*
+ * Copyright 2003-2017 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.
+ */
+
+/*
+ * Save and load mounts of the compound storage to/from the state file.
+ *
+ */
+
+#include "config.h"
+#include "StorageState.hxx"
+#include "fs/io/TextFile.hxx"
+#include "fs/io/BufferedOutputStream.hxx"
+#include "storage/Registry.hxx"
+#include "storage/CompositeStorage.hxx"
+#include "db/plugins/simple/SimpleDatabasePlugin.hxx"
+#include "util/StringCompare.hxx"
+#include "util/Domain.hxx"
+#include "Instance.hxx"
+#include "IOThread.hxx"
+#include "Log.hxx"
+
+#include <list>
+#include <boost/crc.hpp>
+
+#define MOUNT_STATE_BEGIN        "mount_begin"
+#define MOUNT_STATE_END          "mount_end"
+#define MOUNT_STATE_STORAGE_URI  "uri: "
+#define MOUNT_STATE_MOUNTED_URL  "mounted_url: "
+
+static constexpr Domain storage_domain("storage");
+
+void
+storage_state_save(BufferedOutputStream &os, const Instance &instance)
+{
+	const auto visitor = [&os](const char *mount_uri, const Storage &storage) {
+		std::string uri = storage.MapUTF8("");
+		if (uri.empty() || StringIsEmpty(mount_uri))
+			return;
+
+		os.Format(
+			MOUNT_STATE_BEGIN "\n"
+			MOUNT_STATE_STORAGE_URI "%s\n"
+			MOUNT_STATE_MOUNTED_URL "%s\n"
+			MOUNT_STATE_END "\n", mount_uri, uri.c_str());
+	};
+
+	((CompositeStorage*)instance.storage)->VisitMounts(visitor);
+}
+
+bool
+storage_state_restore(const char *line, TextFile &file, Instance &instance)
+{
+	if (!StringStartsWith(line, MOUNT_STATE_BEGIN))
+		return false;
+
+	std::string url;
+	std::string uri;
+	const char* value;
+
+	while ((line = file.ReadLine()) != nullptr) {
+		if (StringStartsWith(line, MOUNT_STATE_END))
+			break;
+
+		if ((value = StringAfterPrefix(line, MOUNT_STATE_MOUNTED_URL)))
+			url = value;
+		else if ((value = StringAfterPrefix(line, MOUNT_STATE_STORAGE_URI)))
+			uri = value;
+		else
+			FormatError(storage_domain, "Unrecognized line in mountpoint state: %s", line);
+	}
+
+	if (url.empty() || uri.empty()) {
+		LogError(storage_domain, "Missing value in mountpoint state.");	
+		return true;
+	}
+
+	FormatDebug(storage_domain, "Restoring mount %s => %s", uri.c_str(), url.c_str());
+
+	auto &event_loop = io_thread_get();
+	Storage *storage = CreateStorageURI(event_loop, url.c_str());
+	if (storage == nullptr) {
+		FormatError(storage_domain, "Unrecognized storage URI: %s", url.c_str());
+		return true;
+	}
+
+#ifdef ENABLE_DATABASE
+	Database *db = instance.database;
+	if (db != nullptr && db->IsPlugin(simple_db_plugin)) {
+		try {
+			((SimpleDatabase *)db)->Mount(uri.c_str(), url.c_str());
+		} catch (...) {
+			throw;
+		}
+	}
+#endif
+
+	((CompositeStorage*)instance.storage)->Mount(uri.c_str(), storage);
+
+	return true;
+}
+
+unsigned
+storage_state_get_hash(const Instance &instance)
+{
+	std::list<std::string> mounts;
+
+	const auto visitor = [&mounts](const char *mount_uri, const Storage &storage) {
+		mounts.push_back(std::string(mount_uri) + ":" + storage.MapUTF8(""));
+	};
+
+	((CompositeStorage*)instance.storage)->VisitMounts(visitor);
+
+	mounts.sort();
+
+	boost::crc_32_type result;
+
+	for (auto mount: mounts) {
+		result.process_bytes(mount.c_str(), mount.length());
+	}
+
+	return result.checksum();
+}

src/storage/StorageState.hxx

+/*
+ * Copyright 2003-2017 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.
+ */
+
+/*
+ * Saving and loading the playlist to/from the state file.
+ *
+ */
+
+#ifndef MPD_STORAGE_STATE_HXX
+#define MPD_STORAGE_STATE_HXX
+
+struct Instance;
+class BufferedOutputStream;
+class TextFile;
+
+void
+storage_state_save(BufferedOutputStream &os, const Instance &instance);
+
+bool
+storage_state_restore(const char *line, TextFile &file, Instance &instance);
+
+/**
+ * Generates a hash number for the current state of the composite storage.
+ * This is used by timer_save_state_file() to determine whether the state
+ * has changed and the state file should be saved.
+ */
+unsigned
+storage_state_get_hash(const Instance &instance);
+
+#endif