FileSystem: extract DirectoryReader, improve the rest

- DirectoryReader is extracted to separate header
- FileSystem.cxx/FileSystem.hxx/DirectoryReader.hxx moved to fs/ subdir
- Functions return true on success, instead of 0 (where applicable)
- ReadLink return result instead of out parameter
- UnlinkFile is renamed to RemoveFile
- CheckExists/CheckIsRegular/CheckIsDirectory are renamed
  to PathExists/FileExists/DirectoryExists

3 files changed, 125 insertions, 100 deletions

diff --git a/src/fs/DirectoryReader.hxx b/src/fs/DirectoryReader.hxx
new file mode 100644
index 000000000..caa1e90ec
--- /dev/null
+++ b/src/fs/DirectoryReader.hxx
@@ -0,0 +1,87 @@
+/*
+ * 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_DIRECTORY_READER_HXX
+#define MPD_FS_DIRECTORY_READER_HXX
+
+#include "check.h"
+#include "Path.hxx"
+
+#include <dirent.h>
+
+/**
+ * Reader for directory entries.
+ */
+class DirectoryReader {
+	DIR *const dirp;
+	dirent *ent;
+public:
+	/**
+	 * Creates new directory reader for the specified #dir.
+	 */
+	explicit DirectoryReader(const Path &dir)
+		: dirp(opendir(dir.c_str())),
+		  ent(nullptr) {
+	}
+
+	DirectoryReader(const DirectoryReader &other) = delete;
+	DirectoryReader &operator=(const DirectoryReader &other) = delete;
+
+	/**
+	 * Destroys this instance.
+	 */
+	~DirectoryReader() {
+		if (!Failed())
+			closedir(dirp);
+	}
+
+	/**
+	 * Checks if directory failed to open. 
+	 */
+	bool Failed() const {
+		return dirp == nullptr;
+	}
+
+	/**
+	 * Checks if directory entry is available.
+	 */
+	bool HasEntry() const {
+		assert(!Failed());
+		return ent != nullptr;
+	}
+
+	/**
+	 * Reads next directory entry.
+	 */
+	bool ReadEntry() {
+		assert(!Failed());
+		ent = readdir(dirp);
+		return HasEntry();
+	}
+
+	/**
+	 * Extracts directory entry that was previously read by #ReadEntry.
+	 */
+	Path GetEntry() const {
+		assert(HasEntry());
+		return Path::FromFS(ent->d_name);
+	}
+};
+
+#endif
diff --git a/src/FileSystem.cxx b/src/fs/FileSystem.cxx
index 70d0d71bb..70ab01fbd 100644
--- a/src/FileSystem.cxx
+++ b/src/fs/FileSystem.cxx
@@ -22,34 +22,22 @@
 
 #include <errno.h>
 
-bool ReadLink(const Path &path, Path &result)
+Path ReadLink(const Path &path)
 {
 #ifdef WIN32
 	(void)path;
-	result = Path::Null();
 	errno = EINVAL;
-	return false;
+	return Path::Null();
 #else
 	char buffer[MPD_PATH_MAX];
 	ssize_t size = readlink(path.c_str(), buffer, MPD_PATH_MAX);
-	int orig_errno = errno;
-	if (size < 0) {
-		result = Path::Null();
-		errno = orig_errno;
-		return false;
-	}
+	if (size < 0)
+		return Path::Null();
 	if (size >= MPD_PATH_MAX) {
-		result = Path::Null();
 		errno = ENOMEM;
-		return false;
+		return Path::Null();
 	}
 	buffer[size] = '\0';
-	result = Path::FromFS(buffer);
-	if (result.IsNull()) {
-		errno = ENOMEM;
-		return false;
-	}
-	errno = orig_errno;
-	return true;
+	return Path::FromFS(buffer);
 #endif
 }
diff --git a/src/FileSystem.hxx b/src/fs/FileSystem.hxx
index cf0fe4bbf..93365ecb4 100644
--- a/src/FileSystem.hxx
+++ b/src/fs/FileSystem.hxx
@@ -17,8 +17,8 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#ifndef MPD_FILESYSTEM_HXX
-#define MPD_FILESYSTEM_HXX
+#ifndef MPD_FS_FILESYSTEM_HXX
+#define MPD_FS_FILESYSTEM_HXX
 
 #include "check.h"
 #include "fd_util.h"
@@ -26,7 +26,6 @@
 #include "Path.hxx"
 
 #include <sys/stat.h>
-#include <dirent.h>
 #include <unistd.h>
 #include <assert.h>
 #include <stdio.h>
@@ -72,132 +71,83 @@ static inline int OpenFile(const Path &file, int flags, int mode)
 /**
  * Wrapper for rename() that uses #Path names.
  */
-static inline int RenameFile(const Path &oldpath, const Path &newpath)
+static inline bool RenameFile(const Path &oldpath, const Path &newpath)
 {
-	return rename(oldpath.c_str(), newpath.c_str());
+	return rename(oldpath.c_str(), newpath.c_str()) == 0;
 }
 
 /**
  * Wrapper for stat() that uses #Path names.
  */
-static inline int StatFile(const Path &file, struct stat &buf)
+static inline bool StatFile(const Path &file, struct stat &buf,
+			    bool follow_symlinks = true)
 {
-	return stat(file.c_str(), &buf);
+#ifdef WIN32
+	(void)follow_symlinks;
+	return stat(file.c_str(), &buf) == 0;
+#else
+	int ret = follow_symlinks
+		? stat(file.c_str(), &buf)
+		: lstat(file.c_str(), &buf);
+	return ret == 0;
+#endif
 }
 
 /**
  * Wrapper for unlink() that uses #Path names.
  */
-static inline int UnlinkFile(const Path &file)
+static inline bool RemoveFile(const Path &file)
 {
-	return unlink(file.c_str());
+	return unlink(file.c_str()) == 0;
 }
 
 /**
  * Wrapper for readlink() that uses #Path names.
- * Unlike readlink() it returns true on success and false otherwise.
- * Use errno to get error code.
  */
-bool ReadLink(const Path &path, Path &result);
+Path ReadLink(const Path &path);
 
 /**
  * Wrapper for access() that uses #Path names.
  */
-static inline int CheckAccess(const Path &path, int mode)
+static inline bool CheckAccess(const Path &path, int mode)
 {
 #ifdef WIN32
 	(void)path;
 	(void)mode;
-	return 0;
+	return true;
 #else
-	return access(path.c_str(), mode);
+	return access(path.c_str(), mode) == 0;
 #endif
 }
 
 /**
- * Checks if #Path is a regular file.
+ * Checks if #Path exists and is a regular file.
  */
-static inline bool CheckIsRegular(const Path &path)
+static inline bool FileExists(const Path &path,
+			      bool follow_symlinks = true)
 {
 	struct stat buf;
-	return StatFile(path, buf) == 0 && S_ISREG(buf.st_mode);
+	return StatFile(path, buf, follow_symlinks) && S_ISREG(buf.st_mode);
 }
 
 /**
- * Checks if #Path is a directory.
+ * Checks if #Path exists and is a directory.
  */
-static inline bool CheckIsDirectory(const Path &path)
+static inline bool DirectoryExists(const Path &path,
+				   bool follow_symlinks = true)
 {
 	struct stat buf;
-	return StatFile(path, buf) == 0 && S_ISDIR(buf.st_mode);
+	return StatFile(path, buf, follow_symlinks) && S_ISDIR(buf.st_mode);
 }
 
 /**
  * Checks if #Path exists.
  */
-static inline bool CheckExists(const Path &path)
+static inline bool PathExists(const Path &path,
+			      bool follow_symlinks = true)
 {
 	struct stat buf;
-	return StatFile(path, buf) == 0;
+	return StatFile(path, buf, follow_symlinks);
 }
 
-/**
- * Reader for directory entries.
- */
-class DirectoryReader {
-	DIR *const dirp;
-	dirent *ent;
-public:
-	/**
-	 * Creates new directory reader for the specified #dir.
-	 */
-	explicit DirectoryReader(const Path &dir)
-		: dirp(opendir(dir.c_str())),
-		  ent(nullptr) {
-	}
-
-	DirectoryReader(const DirectoryReader &other) = delete;
-	DirectoryReader &operator=(const DirectoryReader &other) = delete;
-
-	/**
-	 * Destroys this instance.
-	 */
-	~DirectoryReader() {
-		if (!Failed())
-			closedir(dirp);
-	}
-
-	/**
-	 * Checks if directory failed to open. 
-	 */
-	bool Failed() const {
-		return dirp == nullptr;
-	}
-
-	/**
-	 * Checks if directory entry is available.
-	 */
-	bool HasEntry() const {
-		assert(!Failed());
-		return ent != nullptr;
-	}
-
-	/**
-	 * Reads next directory entry.
-	 */
-	bool ReadEntry() {
-		assert(!Failed());
-		ent = readdir(dirp);
-		return HasEntry();
-	}
-
-	/**
-	 * Extracts directory entry that was previously read by #ReadEntry.
-	 */
-	Path GetEntry() const {
-		assert(HasEntry());
-		return Path::FromFS(ent->d_name);
-	}
-};
-
 #endif