FileSystem: new library for Path-friendly file system routines

Makefile.am

@@ -297,6 +297,7 @@ src_mpd_SOURCES = \
 	src/Volume.cxx src/Volume.hxx \
 	src/SongFilter.cxx src/SongFilter.hxx \
 	src/PlaylistFile.cxx src/PlaylistFile.hxx \
+	src/FileSystem.cxx src/FileSystem.hxx \
 	src/timer.c
 
 #

src/FileSystem.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"
+#include "FileSystem.hxx"
+
+#include <errno.h>
+
+bool ReadLink(const Path &path, Path &result)
+{
+#ifdef WIN32
+	(void)path;
+	result = Path::Null();
+	errno = EINVAL;
+	return false;
+#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 >= MPD_PATH_MAX) {
+		result = Path::Null();
+		errno = ENOMEM;
+		return false;
+	}
+	buffer[size] = '\0';
+	result = Path::FromFS(buffer);
+	if (result.IsNull()) {
+		errno = ENOMEM;
+		return false;
+	}
+	errno = orig_errno;
+	return true;
+#endif
+}

src/FileSystem.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_FILESYSTEM_HXX
+#define MPD_FILESYSTEM_HXX
+
+#include "check.h"
+#include "fd_util.h"
+
+#include "Path.hxx"
+
+#include <sys/stat.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <assert.h>
+#include <stdio.h>
+
+namespace FOpenMode {
+/**
+ * Open mode for reading text files.
+ */
+constexpr Path::const_pointer ReadText = "r";
+
+/**
+ * Open mode for reading binary files.
+ */
+constexpr Path::const_pointer ReadBinary = "rb";
+
+/**
+ * Open mode for writing text files.
+ */
+constexpr Path::const_pointer WriteText = "w";
+
+/**
+ * Open mode for writing binary files.
+ */
+constexpr Path::const_pointer WriteBinary = "wb";
+}
+
+/**
+ * Wrapper for fopen() that uses #Path names.
+ */
+static inline FILE *FOpen(const Path &file, Path::const_pointer mode)
+{
+	return fopen(file.c_str(), mode);
+}
+
+/**
+ * Wrapper for open_cloexec() that uses #Path names.
+ */
+static inline int OpenFile(const Path &file, int flags, int mode)
+{
+	return open_cloexec(file.c_str(), flags, mode);
+}
+
+/**
+ * Wrapper for rename() that uses #Path names.
+ */
+static inline int RenameFile(const Path &oldpath, const Path &newpath)
+{
+	return rename(oldpath.c_str(), newpath.c_str());
+}
+
+/**
+ * Wrapper for stat() that uses #Path names.
+ */
+static inline int StatFile(const Path &file, struct stat &buf)
+{
+	return stat(file.c_str(), &buf);
+}
+
+/**
+ * Wrapper for unlink() that uses #Path names.
+ */
+static inline int UnlinkFile(const Path &file)
+{
+	return unlink(file.c_str());
+}
+
+/**
+ * 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);
+
+/**
+ * Wrapper for access() that uses #Path names.
+ */
+static inline int CheckAccess(const Path &path, int mode)
+{
+#ifdef WIN32
+	(void)path;
+	(void)mode;
+	return 0;
+#else
+	return access(path.c_str(), mode);
+#endif
+}
+
+/**
+ * Checks if #Path is a regular file.
+ */
+static inline bool CheckIsRegular(const Path &path)
+{
+	struct stat buf;
+	return StatFile(path, buf) == 0 && S_ISREG(buf.st_mode);
+}
+
+/**
+ * Checks if #Path is a directory.
+ */
+static inline bool CheckIsDirectory(const Path &path)
+{
+	struct stat buf;
+	return StatFile(path, buf) == 0 && S_ISDIR(buf.st_mode);
+}
+
+/**
+ * Checks if #Path exists.
+ */
+static inline bool CheckExists(const Path &path)
+{
+	struct stat buf;
+	return StatFile(path, buf) == 0;
+}
+
+/**
+ * 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