StorageCommands: add command "listmounts"

src/command/AllCommands.cxx

@@ -107,6 +107,7 @@ static const struct command commands[] = {
 	{ "list", PERMISSION_READ, 1, -1, handle_list },
 	{ "listall", PERMISSION_READ, 0, 1, handle_listall },
 	{ "listallinfo", PERMISSION_READ, 0, 1, handle_listallinfo },
+	{ "listmounts", PERMISSION_READ, 0, 0, handle_listmounts },
 #endif
 #ifdef ENABLE_NEIGHBOR_PLUGINS
 	{ "listneighbors", PERMISSION_READ, 0, 0, handle_listneighbors },

src/command/StorageCommands.cxx

@@ -21,13 +21,63 @@
 #include "StorageCommands.hxx"
 #include "CommandError.hxx"
 #include "protocol/Result.hxx"
+#include "util/UriUtil.hxx"
 #include "util/Error.hxx"
+#include "fs/Traits.hxx"
 #include "client/Client.hxx"
 #include "Partition.hxx"
 #include "Instance.hxx"
 #include "storage/Registry.hxx"
 #include "storage/CompositeStorage.hxx"
 
+static void
+print_storage_uri(Client &client, const Storage &storage)
+{
+	std::string uri = storage.MapUTF8("");
+	if (uri.empty())
+		return;
+
+	if (PathTraitsFS::IsAbsolute(uri.c_str())) {
+		/* storage points to local directory */
+
+		if (!client.IsLocal())
+			/* only "local" clients may see local paths
+			   (same policy as with the "config"
+			   command) */
+			return;
+	} else {
+		/* hide username/passwords from client */
+
+		std::string allocated = uri_remove_auth(uri.c_str());
+		if (!allocated.empty())
+			uri = std::move(allocated);
+	}
+
+	client_printf(client, "storage: %s\n", uri.c_str());
+}
+
+CommandResult
+handle_listmounts(Client &client, gcc_unused int argc, gcc_unused char *argv[])
+{
+	Storage *_composite = client.partition.instance.storage;
+	if (_composite == nullptr) {
+		command_error(client, ACK_ERROR_NO_EXIST, "No database");
+		return CommandResult::ERROR;
+	}
+
+	CompositeStorage &composite = *(CompositeStorage *)_composite;
+
+	const auto visitor = [&client](const char *mount_uri,
+				       const Storage &storage){
+		client_printf(client, "mount: %s\n", mount_uri);
+		print_storage_uri(client, storage);
+	};
+
+	composite.VisitMounts(visitor);
+
+	return CommandResult::OK;
+}
+
 CommandResult
 handle_mount(Client &client, gcc_unused int argc, char *argv[])
 {

src/command/StorageCommands.hxx

@@ -25,6 +25,9 @@
 class Client;
 
 CommandResult
+handle_listmounts(Client &client, int argc, char *argv[]);
+
+CommandResult
 handle_mount(Client &client, int argc, char *argv[]);
 
 #endif

src/storage/CompositeStorage.hxx

@@ -95,6 +95,18 @@ public:
 	CompositeStorage();
 	virtual ~CompositeStorage();
 
+	/**
+	 * Call the given function for each mounted storage, including
+	 * the root storage.  Passes mount point URI and the a const
+	 * Storage reference to the function.
+	 */
+	template<typename T>
+	void VisitMounts(T t) const {
+		const ScopeLock protect(mutex);
+		std::string uri;
+		VisitMounts(uri, root, t);
+	}
+
 	void Mount(const char *uri, Storage *storage);
 	bool Unmount(const char *uri);
 
@@ -112,6 +124,26 @@ public:
 	virtual const char *MapToRelativeUTF8(const char *uri) const override;
 
 private:
+	template<typename T>
+	void VisitMounts(std::string &uri, const Directory &directory,
+			 T t) const {
+		const Storage *const storage = directory.storage;
+		if (storage != nullptr)
+			t(uri.c_str(), *storage);
+
+		if (!uri.empty())
+			uri.push_back('/');
+
+		const size_t uri_length = uri.length();
+
+		for (const auto &i : directory.children) {
+			uri.resize(uri_length);
+			uri.append(i.first);
+
+			VisitMounts(uri, i.second, t);
+		}
+	}
+
 	gcc_pure
 	FindResult FindStorage(const char *uri) const;
 	FindResult FindStorage(const char *uri, Error &error) const;