backends: Add ability to specify different folders depending on backend

Fixes #774

Author: Chris Townsend

include/multipass/platform.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017-2018 Canonical, Ltd.
+ * Copyright (C) 2017-2019 Canonical, Ltd.
  *
  * 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
@@ -13,8 +13,6 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Authored by: Alberto Aguirre <[email protected]>
- *
  */
 
 #ifndef MULTIPASS_PLATFORM_H
@@ -34,6 +32,7 @@ namespace platform
 {
 std::string default_server_address();
 VirtualMachineFactory::UPtr vm_backend(const Path& data_dir);
+Path backend_specific_dir(const Path& original_path);
 logging::Logger::UPtr make_logger(logging::Level level);
 UpdatePrompt::UPtr make_update_prompt();
 int chown(const char* path, unsigned int uid, unsigned int gid);

src/daemon/daemon.cpp

@@ -193,8 +193,8 @@ auto name_from(const std::string& requested_name, mp::NameGenerator& name_gen, c
 
 std::unordered_map<std::string, mp::VMSpecs> load_db(const mp::Path& data_path, const mp::Path& cache_path)
 {
-    QDir data_dir{data_path};
-    QDir cache_dir{cache_path};
+    QDir data_dir{mp::platform::backend_specific_dir(data_path)};
+    QDir cache_dir{mp::platform::backend_specific_dir(cache_path)};
     QFile db_file{data_dir.filePath(instance_db_name)};
     auto opened = db_file.open(QIODevice::ReadOnly);
     if (!opened)
@@ -1756,7 +1756,7 @@ void mp::Daemon::persist_instances()
         auto key = QString::fromStdString(record.first);
         instance_records_json.insert(key, vm_spec_to_json(record.second));
     }
-    QDir data_dir{config->data_directory};
+    QDir data_dir{mp::platform::backend_specific_dir(config->data_directory)};
     mp::write_json(instance_records_json, data_dir.filePath(instance_db_name));
 }
 

src/daemon/default_vm_image_vault.cpp

@@ -20,6 +20,7 @@
 
 #include <multipass/exceptions/create_image_exception.h>
 #include <multipass/logging/log.h>
+#include <multipass/path.h>
 #include <multipass/platform.h>
 #include <multipass/query.h>
 #include <multipass/rpc/multipass.grpc.pb.h>
@@ -248,8 +249,8 @@ mp::DefaultVMImageVault::DefaultVMImageVault(std::vector<VMImageHost*> image_hos
                                              mp::Path cache_dir_path, mp::Path data_dir_path, mp::days days_to_expire)
     : image_hosts{image_hosts},
       url_downloader{downloader},
-      cache_dir{QDir(cache_dir_path).filePath("vault")},
-      data_dir{QDir(data_dir_path).filePath("vault")},
+      cache_dir{QDir(mp::platform::backend_specific_dir(cache_dir_path)).filePath("vault")},
+      data_dir{QDir(mp::platform::backend_specific_dir(data_dir_path)).filePath("vault")},
       instances_dir(data_dir.filePath("instances")),
       images_dir(cache_dir.filePath("images")),
       days_to_expire{days_to_expire},

src/platform/platform_linux.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2017-2018 Canonical, Ltd.
+ * Copyright (C) 2017-2019 Canonical, Ltd.
  *
  * 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
@@ -13,8 +13,6 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Authored by: Alberto Aguirre <[email protected]>
- *
  */
 
 #include <multipass/platform.h>
@@ -61,6 +59,11 @@ mp::VirtualMachineFactory::UPtr mp::platform::vm_backend(const mp::Path& data_di
     throw std::runtime_error("Invalid virtualization driver set in the environment");
 }
 
+mp::Path mp::platform::backend_specific_dir(const mp::Path& original_path)
+{
+    return original_path;
+}
+
 mp::UpdatePrompt::UPtr mp::platform::make_update_prompt()
 {
     return std::make_unique<DisabledUpdatePrompt>();