[wpinet] Move network portions of wpiutil into new wpinet library (#4077)

wpinet/src/main/native/cpp/uv/Signal.cpp

@@ -0,0 +1,32 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include "wpinet/uv/Signal.h"
+
+#include "wpinet/uv/Loop.h"
+
+namespace wpi::uv {
+
+std::shared_ptr<Signal> Signal::Create(Loop& loop) {
+  auto h = std::make_shared<Signal>(private_init{});
+  int err = uv_signal_init(loop.GetRaw(), h->GetRaw());
+  if (err < 0) {
+    loop.ReportError(err);
+    return nullptr;
+  }
+  h->Keep();
+  return h;
+}
+
+void Signal::Start(int signum) {
+  Invoke(
+      &uv_signal_start, GetRaw(),
+      [](uv_signal_t* handle, int signum) {
+        Signal& h = *static_cast<Signal*>(handle->data);
+        h.signal(signum);
+      },
+      signum);
+}
+
+}  // namespace wpi::uv