net/SocketPair: convenience wrapper for UniqueSocketDescriptor::Creat…

…eSocketPair()
CM4all · Nov 7, 2023 · 763e7d3 · 763e7d3
1 parent e95d8e7
commit 763e7d3
Show file tree

Hide file tree

Showing 6 changed files with 112 additions and 17 deletions.
diff --git a/src/net/SocketPair.cxx b/src/net/SocketPair.cxx
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <[email protected]>
+
+#include "SocketPair.hxx"
+#include "SocketError.hxx"
+
+static inline std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+_CreateSocketPair(int domain, int type, int protocol)
+{
+	int sv[2];
+	if (socketpair(domain, type, protocol, sv))
+		throw MakeSocketError("socketpair() failed");
+
+	return {
+		UniqueSocketDescriptor{sv[0]},
+		UniqueSocketDescriptor{sv[1]},
+	};
+}
+
+std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPair(int domain, int type, int protocol)
+{
+#ifdef SOCK_CLOEXEC
+	/* implemented since Linux 2.6.27 */
+	type |= SOCK_CLOEXEC;
+#endif
+
+	return _CreateSocketPair(domain, type, protocol);
+}
+
+std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPairNonBlock(int domain, int type, int protocol)
+{
+#ifdef SOCK_NONBLOCK
+	type |= SOCK_NONBLOCK;
+#endif
+
+	return CreateSocketPair(domain, type, protocol);
+}
diff --git a/src/net/SocketPair.hxx b/src/net/SocketPair.hxx
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <[email protected]>
+
+#pragma once
+
+#include "UniqueSocketDescriptor.hxx"
+
+#include <utility>
+
+#include <sys/socket.h>
+
+class UniqueSocketDescriptor;
+
+/**
+ * Wrapper for socketpair().
+ *
+ * Throws on error.
+ */
+std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPair(int domain, int type, int protocol=0);
+
+/**
+ * Shortcut for CreateSocketPair(AF_LOCAL, type).
+ */
+static std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPair(int type)
+{
+	return CreateSocketPair(AF_LOCAL, type);
+}
+
+/**
+ * Like CreateSocketPair(), but with SOCK_NONBLOCK (if available).
+ */
+std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPairNonBlock(int domain, int type, int protocol=0);
+
+/**
+ * Shortcut for CreateSocketPairNonBlock(AF_LOCAL, type).
+ */
+static std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateSocketPairNonBlock(int type)
+{
+	return CreateSocketPairNonBlock(AF_LOCAL, type);
+}
+
+/**
+ * Shortcut for CreateSocketPair(SOCK_STREAM).
+ */
+static inline std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateStreamSocketPair()
+{
+	return CreateSocketPair(SOCK_STREAM);
+}
+
+/**
+ * Shortcut for CreateSocketPairNonBlock(SOCK_STREAM).
+ */
+static inline std::pair<UniqueSocketDescriptor, UniqueSocketDescriptor>
+CreateStreamSocketPairNonBlock()
+{
+	return CreateSocketPairNonBlock(SOCK_STREAM);
+}
diff --git a/src/net/meson.build b/src/net/meson.build
@@ -16,6 +16,7 @@ net_sources = [
   'Interface.cxx',
   'SocketDescriptor.cxx',
   'UniqueSocketDescriptor.cxx',
+  'SocketPair.cxx',
   'SocketConfig.cxx',
   'RBindSocket.cxx',
   'RConnectSocket.cxx',

diff --git a/src/spawn/Client.cxx b/src/spawn/Client.cxx
@@ -13,6 +13,7 @@
 #include "Mount.hxx"
 #include "ExitListener.hxx"
 #include "system/Error.hxx"
+#include "net/SocketPair.hxx"
 #include "util/PrintException.hxx"
 
 #include <stdexcept>
@@ -126,11 +127,7 @@ SpawnServerClient::Connect()
 {
 	CheckOrAbort();
 
-	UniqueSocketDescriptor local_socket, remote_socket;
-	if (!UniqueSocketDescriptor::CreateSocketPairNonBlock(AF_LOCAL, SOCK_SEQPACKET, 0,
-							      local_socket,
-							      remote_socket))
-		throw MakeErrno("socketpair() failed");
+	auto [local_socket, remote_socket] = CreateSocketPairNonBlock(AF_LOCAL, SOCK_SEQPACKET);
 
 	static constexpr SpawnRequestCommand cmd = SpawnRequestCommand::CONNECT;
 
@@ -143,7 +140,7 @@ SpawnServerClient::Connect()
 		std::throw_with_nested(std::runtime_error("Spawn server failed"));
 	}
 
-	return local_socket;
+	return std::move(local_socket);
 }
 
 static void

diff --git a/src/spawn/Launch.cxx b/src/spawn/Launch.cxx
@@ -15,6 +15,7 @@
 #include "system/Mount.hxx"
 #include "system/ProcessName.hxx"
 #include "net/UniqueSocketDescriptor.hxx"
+#include "net/SocketPair.hxx"
 #include "io/Open.hxx"
 #include "io/SmallTextFile.hxx"
 #include "io/UniqueFileDescriptor.hxx"
@@ -307,13 +308,10 @@ LaunchSpawnServer(const SpawnConfig &config, SpawnHook *hook,
 UniqueSocketDescriptor
 LaunchSpawnServer(const SpawnConfig &config, SpawnHook *hook)
 {
-	UniqueSocketDescriptor s1, s2;
-	if (!UniqueSocketDescriptor::CreateSocketPairNonBlock(AF_LOCAL, SOCK_SEQPACKET, 0,
-							      s1, s2))
-		throw MakeErrno("socketpair() failed");
+	auto [for_client, for_server] = CreateSocketPairNonBlock(SOCK_SEQPACKET);
 
-	LaunchSpawnServer(config, hook, std::move(s1),
-			  [&s2](){ s2.Close(); });
+	LaunchSpawnServer(config, hook, std::move(for_server),
+			  [&]{ for_client.Close(); });
 
-	return s2;
+	return std::move(for_client);
 }
diff --git a/test/net/TestLog.cxx b/test/net/TestLog.cxx
@@ -7,6 +7,7 @@
 #include "net/log/Parser.hxx"
 #include "net/log/Datagram.hxx"
 #include "net/SocketError.hxx"
+#include "net/SocketPair.hxx"
 #include "net/UniqueSocketDescriptor.hxx"
 #include "http/Method.hxx"
 #include "http/Status.hxx"
@@ -107,10 +108,7 @@ TEST(Log, Serializer)
 static auto
 SendReceive(const Net::Log::Datagram &src)
 {
-	UniqueSocketDescriptor a, b;
-	if (!UniqueSocketDescriptor::CreateSocketPair(AF_LOCAL, SOCK_SEQPACKET,
-						      0, a, b))
-		throw MakeSocketError("Failed to create socket pair");
+	auto [a, b] = CreateSocketPair(SOCK_SEQPACKET);
 
 	Net::Log::Send(a, src);