system/UniqueFileDescriptor: new auto-closing FileDescriptor wrapper

Makefile.am

@@ -493,6 +493,7 @@ libsystem_a_SOURCES = \
 	src/system/Error.hxx \
 	src/system/FatalError.cxx src/system/FatalError.hxx \
 	src/system/FileDescriptor.cxx src/system/FileDescriptor.hxx \
+	src/system/UniqueFileDescriptor.hxx \
 	src/system/fd_util.c src/system/fd_util.h \
 	src/system/EventPipe.cxx src/system/EventPipe.hxx \
 	src/system/EventFD.cxx src/system/EventFD.hxx \

src/system/UniqueFileDescriptor.hxx

@@ -0,0 +1,151 @@
+/*
+ * Copyright (C) 2012-2017 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef UNIQUE_FILE_DESCRIPTOR_HXX
+#define UNIQUE_FILE_DESCRIPTOR_HXX
+
+#include "FileDescriptor.hxx"
+
+#include <utility>
+
+/**
+ * An OO wrapper for a UNIX file descriptor.
+ */
+class UniqueFileDescriptor : protected FileDescriptor {
+public:
+	UniqueFileDescriptor():FileDescriptor(FileDescriptor::Undefined()) {}
+
+protected:
+	explicit UniqueFileDescriptor(int _fd):FileDescriptor(_fd) {
+		assert(IsDefined());
+	}
+
+public:
+	explicit UniqueFileDescriptor(FileDescriptor _fd)
+		:FileDescriptor(_fd) {}
+
+	UniqueFileDescriptor(UniqueFileDescriptor &&other)
+		:FileDescriptor(other.Steal()) {}
+
+	~UniqueFileDescriptor() {
+		Close();
+	}
+
+	UniqueFileDescriptor &operator=(UniqueFileDescriptor &&other) {
+		std::swap(fd, other.fd);
+		return *this;
+	}
+
+	/**
+	 * Convert this object to its #FileDescriptor base type.
+	 */
+	const FileDescriptor &ToFileDescriptor() const {
+		return *this;
+	}
+
+	using FileDescriptor::IsDefined;
+#ifndef _WIN32
+	using FileDescriptor::IsValid;
+#endif
+	using FileDescriptor::Get;
+	using FileDescriptor::Steal;
+
+protected:
+	void Set(int _fd) {
+		assert(!IsDefined());
+		assert(_fd >= 0);
+
+		FileDescriptor::Set(_fd);
+	}
+
+public:
+	using FileDescriptor::Open;
+	using FileDescriptor::OpenReadOnly;
+
+#ifndef _WIN32
+	using FileDescriptor::OpenNonBlocking;
+
+	static bool CreatePipe(UniqueFileDescriptor &r, UniqueFileDescriptor &w) {
+		return FileDescriptor::CreatePipe(r, w);
+	}
+
+	using FileDescriptor::SetNonBlocking;
+	using FileDescriptor::SetBlocking;
+	using FileDescriptor::EnableCloseOnExec;
+	using FileDescriptor::DisableCloseOnExec;
+	using FileDescriptor::Duplicate;
+
+	static bool CreatePipe(FileDescriptor &r, FileDescriptor &w);
+#endif
+
+#ifdef USE_EVENTFD
+	using FileDescriptor::CreateEventFD;
+#endif
+
+#ifdef USE_SIGNALFD
+	using FileDescriptor::CreateSignalFD;
+#endif
+
+#ifdef HAVE_INOTIFY_INIT
+	using FileDescriptor::CreateInotify;
+#endif
+
+#ifdef HAVE_EVENTFD
+	using FileDescriptor::CreateEventFD;
+#endif
+
+#ifdef HAVE_SIGNALFD
+	using FileDescriptor::CreateSignalFD;
+#endif
+
+#ifdef HAVE_INOTIFY
+	using FileDescriptor::CreateInotify;
+#endif
+
+	bool Close() {
+		return IsDefined() && FileDescriptor::Close();
+	}
+
+	using FileDescriptor::Rewind;
+	using FileDescriptor::Seek;
+	using FileDescriptor::Skip;
+	using FileDescriptor::Tell;
+	using FileDescriptor::GetSize;
+	using FileDescriptor::Read;
+	using FileDescriptor::Write;
+
+#ifndef _WIN32
+	using FileDescriptor::Poll;
+	using FileDescriptor::WaitReadable;
+	using FileDescriptor::WaitWritable;
+	using FileDescriptor::IsReadyForWriting;
+#endif
+};
+
+#endif