fs: implemented standard directories API

Makefile.am

@@ -380,6 +380,7 @@ libfs_a_SOURCES = \
 	src/fs/AllocatedPath.cxx src/fs/AllocatedPath.hxx \
 	src/fs/TextFile.cxx src/fs/TextFile.hxx \
 	src/fs/FileSystem.cxx src/fs/FileSystem.hxx \
+	src/fs/StandardDirectory.cxx src/fs/StandardDirectory.hxx \
 	src/fs/DirectoryReader.hxx
 
 # database plugins

configure.ac

@@ -147,6 +147,7 @@ AC_SEARCH_LIBS([socket], [socket])
 AC_SEARCH_LIBS([gethostbyname], [nsl])
 
 AC_CHECK_FUNCS(pipe2 accept4)
+AC_CHECK_FUNCS(getpwnam_r getpwuid_r)
 MPD_OPTIONAL_FUNC(eventfd, eventfd, USE_EVENTFD)
 MPD_OPTIONAL_FUNC(signalfd, signalfd, USE_SIGNALFD)
 

src/fs/StandardDirectory.cxx

+/*
+ * Copyright (C) 2003-2013 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"
+
+// Use X Desktop guidelines where applicable
+#if !defined(__APPLE__) && !defined(WIN32)
+#define USE_XDG
+#endif
+
+#include "StandardDirectory.hxx"
+#include "FileSystem.hxx"
+
+#include <array>
+
+#ifdef WIN32
+#include <windows.h>
+#include <shlobj.h>
+#else
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <pwd.h>
+#endif
+
+#ifdef USE_XDG
+#include "util/CharUtil.hxx"
+#include "util/StringUtil.hxx"
+#include "TextFile.hxx"
+#include <string.h>
+#include <utility>
+#endif
+
+#ifndef WIN32
+class PasswdEntry
+{
+#if defined(HAVE_GETPWNAM_R) || defined(HAVE_GETPWUID_R)
+	std::array<char, 16 * 1024> buf;
+	passwd pw;
+#endif
+
+	passwd *result;
+public:
+	PasswdEntry() : result(nullptr) { }
+
+	bool ReadByName(const char *name) {
+#ifdef HAVE_GETPWNAM_R
+		getpwnam_r(name, &pw, buf.data(), buf.size(), &result);
+#else
+		result = getpwnam(name);
+#endif
+		return result != nullptr;
+	}
+
+	bool ReadByUid(uid_t uid) {
+#ifdef HAVE_GETPWUID_R
+		getpwuid_r(uid, &pw, buf.data(), buf.size(), &result);
+#else
+		result = getpwuid(uid);
+#endif
+		return result != nullptr;
+	}
+
+	const passwd *operator->() {
+		assert(result != nullptr);
+		return result;
+	}
+};
+#endif
+
+static inline bool IsValidPathString(PathTraitsFS::const_pointer path)
+{
+	return path != nullptr && *path != '\0';
+}
+
+static inline bool IsValidDir(PathTraitsFS::const_pointer dir)
+{
+	return PathTraitsFS::IsAbsolute(dir) &&
+	       DirectoryExists(Path::FromFS(dir));
+}
+
+static inline AllocatedPath SafePathFromFS(PathTraitsFS::const_pointer dir)
+{
+	if (IsValidPathString(dir) && IsValidDir(dir))
+		return AllocatedPath::FromFS(dir);
+	return AllocatedPath::Null();
+}
+
+#ifdef WIN32
+static AllocatedPath GetStandardDir(int folder_id)
+{
+	std::array<char, MAX_PATH> dir;
+	auto ret = SHGetFolderPath(nullptr, folder_id | CSIDL_FLAG_DONT_VERIFY,
+				   nullptr, SHGFP_TYPE_CURRENT, dir.data());
+	if (FAILED(ret))
+		return AllocatedPath::Null();
+	return SafePathFromFS(dir.data());
+}
+#endif
+
+#ifdef USE_XDG
+
+static const char home_prefix[] = "$HOME/";
+
+static bool ParseConfigLine(const char *line, const char *dir_name,
+			    AllocatedPath &result_dir)
+{
+	// strip leading white space
+	line = strchug_fast(line);
+
+	// check for end-of-line or comment
+	if (*line == '\0' || *line == '#')
+		return false;
+
+	// check if current setting is for requested dir
+	if (!StringStartsWith(line, dir_name))
+		return false;
+	line += strlen(dir_name);
+
+	// strip equals sign and spaces around it
+	line = strchug_fast(line);
+	if (*line != '=')
+		return false;
+	++line;
+	line = strchug_fast(line);
+
+	// check if path is quoted
+	bool quoted = false;
+	if (*line == '"') {
+		++line;
+		quoted = true;
+	}
+
+	// check if path is relative to $HOME
+	bool home_relative = false;
+	if (StringStartsWith(line, home_prefix)) {
+		line += strlen(home_prefix);
+		home_relative = true;
+	}
+
+
+	const char *line_end;
+	// find end of the string
+	if (quoted) {
+		line_end = strrchr(line, '"');
+		if (line_end == nullptr)
+			return true;
+	} else {
+		line_end = line + strlen(line);
+		while (line < line_end && IsWhitespaceNotNull(line_end[-1]))
+			--line_end;
+	}
+
+	// check for empty result
+	if (line == line_end)
+		return true;
+
+	// build the result path	
+	std::string path(line, line_end);
+
+	auto result = AllocatedPath::Null();
+	if (home_relative) {
+		auto home = GetHomeDir();
+		if (home.IsNull())
+			return true;
+		result = AllocatedPath::Build(home, path.c_str());
+	} else {
+		result = AllocatedPath::FromFS(std::move(path));
+	}
+
+	if (IsValidDir(result.c_str())) {
+		result_dir = std::move(result);
+		return true;
+	}
+	return true;
+}
+
+static AllocatedPath GetUserDir(const char *name)
+{
+	auto result = AllocatedPath::Null();
+	auto config_dir = GetUserConfigDir();
+	if (config_dir.IsNull())
+		return result;
+	auto dirs_file = AllocatedPath::Build(config_dir, "user-dirs.dirs");
+	TextFile input(dirs_file);
+	if (input.HasFailed())
+		return result;
+	const char *line;
+	while ((line = input.ReadLine()) != nullptr)
+		if (ParseConfigLine(line, name, result))
+			return result;
+	return result;
+}
+
+#endif
+
+AllocatedPath GetUserConfigDir()
+{
+#if defined(WIN32)
+	return GetStandardDir(CSIDL_LOCAL_APPDATA);
+#elif defined(USE_XDG)
+	// Check for $XDG_CONFIG_HOME
+	auto config_home = getenv("XDG_CONFIG_HOME");
+	if (IsValidPathString(config_home) && IsValidDir(config_home))
+		return AllocatedPath::FromFS(config_home);
+
+	// Check for $HOME/.config
+	auto home = GetHomeDir();
+	if (!home.IsNull()) {
+		AllocatedPath fallback = AllocatedPath::Build(home, ".config");
+		if (IsValidDir(fallback.c_str()))
+			return fallback;
+	}
+
+	return AllocatedPath::Null();
+#else
+	return AllocatedPath::Null();
+#endif
+}
+
+AllocatedPath GetUserMusicDir()
+{
+#if defined(WIN32)
+	return GetStandardDir(CSIDL_MYMUSIC);	
+#elif defined(USE_XDG)
+	return GetUserDir("XDG_MUSIC_DIR");
+#else
+	return AllocatedPath::Null();
+#endif
+}
+
+#ifdef WIN32
+
+AllocatedPath GetSystemConfigDir()
+{
+	return GetStandardDir(CSIDL_COMMON_APPDATA);
+}
+
+AllocatedPath GetAppBaseDir()
+{
+	std::array<char, MAX_PATH> app;
+	auto ret = GetModuleFileName(nullptr, app.data(), app.size());
+
+	// Check for error
+	if (ret == 0)
+		return AllocatedPath::Null();
+
+	// Check for truncation
+	if (ret == app.size() && GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+		return AllocatedPath::Null();
+
+	auto app_path = AllocatedPath::FromFS(app.data());
+	return app_path.GetDirectoryName().GetDirectoryName();
+}
+
+#else
+
+AllocatedPath GetHomeDir()
+{
+	auto home = getenv("HOME");
+	if (IsValidPathString(home) && IsValidDir(home))
+		return AllocatedPath::FromFS(home);
+	PasswdEntry pw;
+	if (pw.ReadByUid(getuid()))
+		return SafePathFromFS(pw->pw_dir);
+	return AllocatedPath::Null();
+}
+
+AllocatedPath GetHomeDir(const char *user_name)
+{
+	assert(user_name != nullptr);
+	PasswdEntry pw;
+	if (pw.ReadByName(user_name))
+		return SafePathFromFS(pw->pw_dir);
+	return AllocatedPath::Null();
+}
+
+#endif

src/fs/StandardDirectory.hxx

+/*
+ * Copyright (C) 2003-2013 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_FS_STANDARD_DIRECTORY_HXX
+#define MPD_FS_STANDARD_DIRECTORY_HXX
+
+#include "check.h"
+#include "AllocatedPath.hxx"
+
+/**
+ * Obtains configuration directory for the current user.
+ */
+AllocatedPath GetUserConfigDir();
+
+/**
+ * Obtains music directory for the current user.
+ */
+AllocatedPath GetUserMusicDir();
+
+#ifdef WIN32
+
+/**
+ * Obtains system configuration directory.
+ */
+AllocatedPath GetSystemConfigDir();
+
+/**
+ * Obtains application application base directory.
+ * Application base directory is a directory that contains 'bin' folder
+ * for current executable.
+ */
+AllocatedPath GetAppBaseDir();
+
+#else
+
+/**
+ * Obtains home directory for the current user.
+ */
+AllocatedPath GetHomeDir();
+
+/**
+ * Obtains home directory for the specified user.
+ */
+AllocatedPath GetHomeDir(const char *user_name);
+
+#endif
+
+#endif