d7744d2b8e
Mounting one storage URI twice on different mount points can lead to conflicts with the database cache file, and it doesn't make a lot of sense. But most importantly, our udisks storage plugin will unmount the disk from the kernel VFS, and if two exist, they will compete with each others. We could (and should) fix this in the udisks storage plugin, but for now, this workaround is good enough (and useful).
165 lines
4.4 KiB
C++
165 lines
4.4 KiB
C++
/*
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* Copyright 2003-2018 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* Save and load mounts of the compound storage to/from the state file.
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*
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*/
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#include "StorageState.hxx"
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#include "fs/io/TextFile.hxx"
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#include "fs/io/BufferedOutputStream.hxx"
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#include "storage/Registry.hxx"
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#include "storage/CompositeStorage.hxx"
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#include "db/plugins/simple/SimpleDatabasePlugin.hxx"
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#include "util/StringCompare.hxx"
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#include "util/Domain.hxx"
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#include "Instance.hxx"
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#include "Log.hxx"
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#ifdef __clang__
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/* ignore -Wcomma due to strange code in boost/array.hpp (in Boost
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1.72) */
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#pragma GCC diagnostic ignored "-Wcomma"
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#endif
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#include <boost/crc.hpp>
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#include <set>
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#define MOUNT_STATE_BEGIN "mount_begin"
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#define MOUNT_STATE_END "mount_end"
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#define MOUNT_STATE_STORAGE_URI "uri: "
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#define MOUNT_STATE_MOUNTED_URL "mounted_url: "
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static constexpr Domain storage_domain("storage");
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void
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storage_state_save(BufferedOutputStream &os, const Instance &instance)
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{
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if (instance.storage == nullptr)
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return;
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const auto visitor = [&os](const char *mount_uri, const Storage &storage) {
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std::string uri = storage.MapUTF8("");
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if (uri.empty() || StringIsEmpty(mount_uri))
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return;
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os.Format(
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MOUNT_STATE_BEGIN "\n"
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MOUNT_STATE_STORAGE_URI "%s\n"
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MOUNT_STATE_MOUNTED_URL "%s\n"
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MOUNT_STATE_END "\n", mount_uri, uri.c_str());
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};
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((CompositeStorage*)instance.storage)->VisitMounts(visitor);
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}
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bool
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storage_state_restore(const char *line, TextFile &file, Instance &instance)
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{
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if (!StringStartsWith(line, MOUNT_STATE_BEGIN))
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return false;
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std::string url;
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std::string uri;
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const char* value;
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while ((line = file.ReadLine()) != nullptr) {
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if (StringStartsWith(line, MOUNT_STATE_END))
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break;
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if ((value = StringAfterPrefix(line, MOUNT_STATE_MOUNTED_URL)))
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url = value;
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else if ((value = StringAfterPrefix(line, MOUNT_STATE_STORAGE_URI)))
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uri = value;
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else
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FormatError(storage_domain, "Unrecognized line in mountpoint state: %s", line);
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}
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if (instance.storage == nullptr)
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/* without storage (a CompositeStorage instance), we
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cannot mount, and therefore we silently ignore the
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state file */
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return true;
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if (url.empty() || uri.empty()) {
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LogError(storage_domain, "Missing value in mountpoint state.");
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return true;
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}
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FormatDebug(storage_domain, "Restoring mount %s => %s", uri.c_str(), url.c_str());
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auto &composite_storage = *(CompositeStorage *)instance.storage;
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if (composite_storage.IsMountPoint(uri.c_str())) {
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LogError(storage_domain, "Mount point busy");
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return true;
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}
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if (composite_storage.IsMounted(url.c_str())) {
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LogError(storage_domain, "This storage is already mounted");
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return true;
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}
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auto &event_loop = instance.io_thread.GetEventLoop();
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auto storage = CreateStorageURI(event_loop, url.c_str());
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if (storage == nullptr) {
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FormatError(storage_domain, "Unrecognized storage URI: %s", url.c_str());
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return true;
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}
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if (auto *db = dynamic_cast<SimpleDatabase *>(instance.GetDatabase())) {
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try {
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db->Mount(uri.c_str(), url.c_str());
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} catch (...) {
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FormatError(std::current_exception(),
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"Failed to restore mount to %s",
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url.c_str());
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return true;
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}
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}
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composite_storage.Mount(uri.c_str(), std::move(storage));
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return true;
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}
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unsigned
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storage_state_get_hash(const Instance &instance)
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{
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if (instance.storage == nullptr)
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return 0;
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std::set<std::string> mounts;
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const auto visitor = [&mounts](const char *mount_uri, const Storage &storage) {
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mounts.emplace(std::string(mount_uri) + ":" + storage.MapUTF8(""));
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};
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((CompositeStorage*)instance.storage)->VisitMounts(visitor);
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boost::crc_32_type result;
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for (auto mount: mounts) {
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result.process_bytes(mount.c_str(), mount.length());
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}
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return result.checksum();
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}
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