storage/nfs: move code to class MemoryStorageDirectoryReader

Read all directory entries into memory and close the struct nfsdir
before returning the StorageDirectoryReader instance.  This is what
libnfs does, anyway.

Makefile.am

@@ -572,6 +572,7 @@ libstorage_a_SOURCES = \
 	src/storage/Registry.cxx src/storage/Registry.hxx \
 	src/storage/StorageInterface.cxx src/storage/StorageInterface.hxx \
 	src/storage/CompositeStorage.cxx src/storage/CompositeStorage.hxx \
+	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/FileInfo.hxx

src/storage/MemoryDirectoryReader.cxx

@@ -0,0 +1,48 @@
+/*
+ * 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 "MemoryDirectoryReader.hxx"
+
+#include <assert.h>
+
+const char *
+MemoryStorageDirectoryReader::Read()
+{
+	if (first)
+		first = false;
+	else
+		entries.pop_front();
+
+	if (entries.empty())
+		return nullptr;
+
+	return entries.front().name.c_str();
+}
+
+bool
+MemoryStorageDirectoryReader::GetInfo(gcc_unused bool follow, FileInfo &info,
+				      gcc_unused Error &error)
+{
+	assert(!first);
+	assert(!entries.empty());
+
+	info = entries.front().info;
+	return true;
+}

src/storage/MemoryDirectoryReader.hxx

@@ -0,0 +1,67 @@
+/*
+ * 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_STORAGE_MEMORY_DIRECTORY_READER_HXX
+#define MPD_STORAGE_MEMORY_DIRECTORY_READER_HXX
+
+#include "check.h"
+#include "StorageInterface.hxx"
+#include "FileInfo.hxx"
+
+#include <string>
+#include <forward_list>
+
+/**
+ * A #StorageDirectoryReader implementation that returns directory
+ * entries from a memory allocation.
+ */
+class MemoryStorageDirectoryReader final : public StorageDirectoryReader {
+public:
+	struct Entry {
+		std::string name;
+
+		FileInfo info;
+
+		template<typename N>
+		explicit Entry(N &&_name):name(std::forward<N>(_name)) {}
+	};
+
+	typedef std::forward_list<Entry> List;
+
+private:
+	List entries;
+
+	bool first;
+
+public:
+	MemoryStorageDirectoryReader()
+		:first(true) {}
+
+	MemoryStorageDirectoryReader(MemoryStorageDirectoryReader &&src)
+		:entries(std::move(src.entries)), first(src.first) {}
+
+	MemoryStorageDirectoryReader(List &&_entries)
+		:entries(std::move(_entries)), first(true) {}
+
+	/* virtual methods from class StorageDirectoryReader */
+	const char *Read() override;
+	bool GetInfo(bool follow, FileInfo &info, Error &error) override;
+};
+
+#endif

src/storage/plugins/NfsStorage.cxx

@@ -22,6 +22,7 @@
 #include "storage/StoragePlugin.hxx"
 #include "storage/StorageInterface.hxx"
 #include "storage/FileInfo.hxx"
+#include "storage/MemoryDirectoryReader.hxx"
 #include "lib/nfs/Domain.hxx"
 #include "lib/nfs/Base.hxx"
 #include "fs/AllocatedPath.hxx"
@@ -36,31 +37,6 @@ extern "C" {
 #include <sys/stat.h>
 #include <fcntl.h>
 
-class NfsDirectoryReader final : public StorageDirectoryReader {
-	const std::string base;
-
-	nfs_context *const ctx;
-	nfsdir *const dir;
-
-	nfsdirent *ent;
-
-	/**
-	 * Buffer for Read() which holds the current file name
-	 * converted to UTF-8.
-	 */
-	std::string name_utf8;
-
-public:
-	NfsDirectoryReader(const char *_base, nfs_context *_ctx, nfsdir *_dir)
-		:base(_base), ctx(_ctx), dir(_dir) {}
-
-	virtual ~NfsDirectoryReader();
-
-	/* virtual methods from class StorageDirectoryReader */
-	const char *Read() override;
-	bool GetInfo(bool follow, FileInfo &info, Error &error) override;
-};
-
 class NfsStorage final : public Storage {
 	const std::string base;
 
@@ -156,23 +132,6 @@ NfsStorage::GetInfo(const char *uri_utf8, gcc_unused bool follow,
 	return ::GetInfo(ctx, path.c_str(), info, error);
 }
 
-StorageDirectoryReader *
-NfsStorage::OpenDirectory(const char *uri_utf8, Error &error)
-{
-	const std::string path = UriToNfsPath(uri_utf8, error);
-	if (path.empty())
-		return nullptr;
-
-	nfsdir *dir;
-	int result = nfs_opendir(ctx, path.c_str(), &dir);
-	if (result < 0) {
-		error.SetErrno(-result, "nfs_opendir() failed");
-		return nullptr;
-	}
-
-	return new NfsDirectoryReader(uri_utf8, ctx, dir);
-}
-
 gcc_pure
 static bool
 SkipNameFS(const char *name)
@@ -182,31 +141,6 @@ SkipNameFS(const char *name)
 		 (name[1] == '.' && name[2] == 0));
 }
 
-NfsDirectoryReader::~NfsDirectoryReader()
-{
-	nfs_closedir(ctx, dir);
-}
-
-const char *
-NfsDirectoryReader::Read()
-{
-	while ((ent = nfs_readdir(ctx, dir)) != nullptr) {
-		const Path name_fs = Path::FromFS(ent->name);
-		if (SkipNameFS(name_fs.c_str()))
-			continue;
-
-		name_utf8 = name_fs.ToUTF8();
-		if (name_utf8.empty())
-			/* ignore files whose name cannot be converted
-			   to UTF-8 */
-			continue;
-
-		return name_utf8.c_str();
-	}
-
-	return nullptr;
-}
-
 static void
 Copy(FileInfo &info, const struct nfsdirent &ent)
 {
@@ -230,14 +164,42 @@ Copy(FileInfo &info, const struct nfsdirent &ent)
 	info.inode = ent.inode;
 }
 
-bool
-NfsDirectoryReader::GetInfo(gcc_unused bool follow, FileInfo &info,
-			    gcc_unused Error &error)
+StorageDirectoryReader *
+NfsStorage::OpenDirectory(const char *uri_utf8, Error &error)
 {
-	assert(ent != nullptr);
+	const std::string path = UriToNfsPath(uri_utf8, error);
+	if (path.empty())
+		return nullptr;
 
-	Copy(info, *ent);
-	return true;
+	nfsdir *dir;
+	int result = nfs_opendir(ctx, path.c_str(), &dir);
+	if (result < 0) {
+		error.SetErrno(-result, "nfs_opendir() failed");
+		return nullptr;
+	}
+
+	MemoryStorageDirectoryReader::List entries;
+
+	const struct nfsdirent *ent;
+	while ((ent = nfs_readdir(ctx, dir)) != nullptr) {
+		const Path name_fs = Path::FromFS(ent->name);
+		if (SkipNameFS(name_fs.c_str()))
+			continue;
+
+		std::string name_utf8 = name_fs.ToUTF8();
+		if (name_utf8.empty())
+			/* ignore files whose name cannot be converted
+			   to UTF-8 */
+			continue;
+
+		entries.emplace_front(std::move(name_utf8));
+		Copy(entries.front().info, *ent);
+	}
+
+	nfs_closedir(ctx, dir);
+
+	/* don't reverse the list - order does not matter */
+	return new MemoryStorageDirectoryReader(std::move(entries));
 }
 
 static Storage *