io/UniqueFileDescriptor: use AdoptTag in the constructors that adopt ownership

src/event/InotifyEvent.cxx

@@ -18,7 +18,7 @@ CreateInotify()
 	if (fd < 0)
 		throw MakeErrno("inotify_init1() failed");
 
-	return UniqueFileDescriptor(fd);
+	return UniqueFileDescriptor(AdoptTag{}, fd);
 }
 
 InotifyEvent::InotifyEvent(EventLoop &event_loop, InotifyHandler &_handler)

src/io/FileDescriptor.cxx

@@ -225,7 +225,7 @@ FileDescriptor::SetPipeCapacity(unsigned capacity) const noexcept
 UniqueFileDescriptor
 FileDescriptor::Duplicate() const noexcept
 {
-	return UniqueFileDescriptor{::dup(Get())};
+	return UniqueFileDescriptor{AdoptTag{}, ::dup(Get())};
 }
 
 bool

src/io/UniqueFileDescriptor.hxx

@@ -4,6 +4,7 @@
 #pragma once
 
 #include "FileDescriptor.hxx" // IWYU pragma: export
+#include "util/TagStructs.hxx"
 
 #include <cassert>
 #include <utility>
@@ -16,10 +17,10 @@ public:
 	UniqueFileDescriptor() noexcept
 		:FileDescriptor(FileDescriptor::Undefined()) {}
 
-	explicit UniqueFileDescriptor(int _fd) noexcept
+	explicit UniqueFileDescriptor(AdoptTag, int _fd) noexcept
 		:FileDescriptor(_fd) {}
 
-	explicit UniqueFileDescriptor(FileDescriptor _fd) noexcept
+	explicit UniqueFileDescriptor(AdoptTag, FileDescriptor _fd) noexcept
 		:FileDescriptor(_fd) {}
 
 	UniqueFileDescriptor(const UniqueFileDescriptor &) = delete;

src/net/SocketDescriptor.cxx

@@ -252,7 +252,7 @@ SocketDescriptor::GetPeerPidfd() const noexcept
 	if (GetOption(SOL_SOCKET, SO_PEERPIDFD, &pidfd, sizeof(pidfd)) < sizeof(pidfd))
 		return {};
 
-	return UniqueFileDescriptor{pidfd};
+	return UniqueFileDescriptor{AdoptTag{}, pidfd};
 }
 
 #endif // __linux__

src/net/UniqueSocketDescriptor.hxx

@@ -58,7 +58,7 @@ public:
 
 #ifndef _WIN32
 	UniqueFileDescriptor MoveToFileDescriptor() && noexcept {
-		return UniqueFileDescriptor{Release().ToFileDescriptor()};
+		return UniqueFileDescriptor{AdoptTag{}, Release().ToFileDescriptor()};
 	}
 #endif
 

src/net/UniqueSocketDescriptor.hxx.orig

@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <max.kellermann@gmail.com>
+
+#pragma once
+
+#include "SocketDescriptor.hxx"
+
+#ifndef _WIN32
+#include "io/UniqueFileDescriptor.hxx"
+#endif
+
+#include <utility>
+
+class StaticSocketAddress;
+
+/**
+ * Wrapper for a socket file descriptor.
+ */
+class UniqueSocketDescriptor : public SocketDescriptor {
+public:
+	UniqueSocketDescriptor() noexcept
+		:SocketDescriptor(SocketDescriptor::Undefined()) {}
+
+	explicit UniqueSocketDescriptor(SocketDescriptor _fd) noexcept
+		:SocketDescriptor(_fd) {}
+#ifndef _WIN32
+	explicit UniqueSocketDescriptor(FileDescriptor _fd) noexcept
+		:SocketDescriptor(_fd) {}
+
+	explicit UniqueSocketDescriptor(UniqueFileDescriptor &&_fd) noexcept
+		:SocketDescriptor(_fd.Release()) {}
+#endif // !_WIN32
+
+	explicit UniqueSocketDescriptor(int _fd) noexcept
+		:SocketDescriptor(_fd) {}
+
+#ifdef _WIN32
+	UniqueSocketDescriptor(UniqueSocketDescriptor &&other) noexcept
+		:SocketDescriptor(std::exchange(other.fd, INVALID_SOCKET)) {}
+#else // !_WIN32
+	UniqueSocketDescriptor(UniqueSocketDescriptor &&other) noexcept
+		:SocketDescriptor(std::exchange(other.fd, -1)) {}
+#endif // !_WIN32
+
+	~UniqueSocketDescriptor() noexcept {
+		if (IsDefined())
+			Close();
+	}
+
+	/**
+	 * Release ownership and return the descriptor as an unmanaged
+	 * #SocketDescriptor instance.
+	 */
+	SocketDescriptor Release() noexcept {
+		return std::exchange(*(SocketDescriptor *)this, Undefined());
+	}
+
+#ifndef _WIN32
+	UniqueFileDescriptor MoveToFileDescriptor() && noexcept {
+		return UniqueFileDescriptor{Release().ToFileDescriptor()};
+	}
+#endif
+
+	UniqueSocketDescriptor &operator=(UniqueSocketDescriptor &&src) noexcept {
+		using std::swap;
+		swap(fd, src.fd);
+		return *this;
+	}
+
+	bool operator==(const UniqueSocketDescriptor &other) const noexcept {
+		return fd == other.fd;
+	}
+
+	/**
+	 * @return an "undefined" instance on error
+	 */
+	UniqueSocketDescriptor AcceptNonBlock() const noexcept {
+		return UniqueSocketDescriptor(SocketDescriptor::AcceptNonBlock());
+	}
+
+	/**
+	 * @return an "undefined" instance on error
+	 */
+	UniqueSocketDescriptor AcceptNonBlock(StaticSocketAddress &address) const noexcept {
+		return UniqueSocketDescriptor(SocketDescriptor::AcceptNonBlock(address));
+	}
+
+#ifndef _WIN32
+	static bool CreateSocketPair(int domain, int type, int protocol,
+				     UniqueSocketDescriptor &a,
+				     UniqueSocketDescriptor &b) noexcept {
+		return SocketDescriptor::CreateSocketPair(domain, type,
+							  protocol,
+							  a, b);
+	}
+
+	static bool CreateSocketPairNonBlock(int domain, int type, int protocol,
+					     UniqueSocketDescriptor &a,
+					     UniqueSocketDescriptor &b) noexcept {
+		return SocketDescriptor::CreateSocketPairNonBlock(domain, type,
+								  protocol,
+								  a, b);
+	}
+#endif
+};

src/system/EpollFD.cxx

@@ -5,7 +5,7 @@
 #include "Error.hxx"
 
 EpollFD::EpollFD()
-	:fd(::epoll_create1(EPOLL_CLOEXEC))
+	:fd(AdoptTag{}, ::epoll_create1(EPOLL_CLOEXEC))
 {
 	if (!fd.IsDefined())
 		throw MakeErrno("epoll_create1() failed");

src/system/EventFD.cxx

@@ -10,7 +10,7 @@
 #include <sys/eventfd.h>
 
 EventFD::EventFD()
-	:fd(::eventfd(0, EFD_NONBLOCK|EFD_CLOEXEC))
+	:fd(AdoptTag{}, ::eventfd(0, EFD_NONBLOCK|EFD_CLOEXEC))
 {
 	if (!fd.IsDefined())
 		throw MakeErrno("eventfd() failed");

src/system/SignalFD.cxx

@@ -17,7 +17,7 @@ SignalFD::Create(const sigset_t &mask)
 		throw MakeErrno("signalfd() failed");
 
 	if (!fd.IsDefined()) {
-		fd = UniqueFileDescriptor{new_fd};
+		fd = UniqueFileDescriptor{AdoptTag{}, new_fd};
 	}
 
 	assert(new_fd == fd.Get());