WIP: listen

Author: milseman

Sources/System/Internals/Syscalls.swift

@@ -129,3 +129,10 @@ internal func system_shutdown(_ socket: CInt, _ how: CInt) -> CInt {
   #endif
   return shutdown(socket, how)
 }
+
+internal func system_listen(_ socket: CInt, _ backlog: CInt) -> CInt {
+  #if ENABLE_MOCKING
+  if mockingEnabled { return _mock(socket, backlog) }
+  #endif
+  return listen(socket, backlog)
+}

Sources/System/Sockets/SocketOperations.swift

@@ -67,4 +67,23 @@ extension SocketDescriptor {
     nothingOrErrno(system_shutdown(self.rawValue, how.rawValue))
   }
 
+  /// Listen for connections on a socket.
+  ///
+  /// Only applies to sockets of connection type `.stream`.
+  ///
+  /// - Parameters:
+  ///   - backlog: the maximum length for the queue of pending connections
+  ///
+  /// The corresponding C function is `listen`.
+  @_alwaysEmitIntoClient
+  public func listen(backlog: Int) throws {
+    try _listen(backlog: backlog).get()
+  }
+
+  @usableFromInline
+  internal func _listen(backlog: Int) -> Result<(), Errno> {
+    nothingOrErrno(system_listen(self.rawValue, CInt(backlog)))
+  }
+
+
 }

Tests/SystemTests/SocketTest.swift

@@ -32,6 +32,10 @@ final class SocketTest: XCTestCase {
         retryOnInterrupt in
         _ = try socket.shutdown(.read)
       },
+      MockTestCase(name: "listen", rawSocket, 999, interruptable: false) {
+        retryOnInterrupt in
+      _ = try socket.listen(backlog: 999)
+      },
     ]
 
     syscallTestCases.forEach { $0.runAllTests() }