source/signal: Implement
diff --git a/.gitignore b/.gitignore
index 9b8c3e2..3c5419c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,4 +51,5 @@
 /test/source_base
 /test/source_event
 /test/source_io
+/test/source_signal
 /test/source_time
diff --git a/src/Makefile.am b/src/Makefile.am
index 74f01f5..236e347 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -30,6 +30,9 @@
 nobase_include_HEADERS += sdeventplus/source/io.hpp
 libsdeventplus_la_SOURCES += sdeventplus/source/io.cpp
 
+nobase_include_HEADERS += sdeventplus/source/signal.hpp
+libsdeventplus_la_SOURCES += sdeventplus/source/signal.cpp
+
 nobase_include_HEADERS += sdeventplus/source/time.hpp
 libsdeventplus_la_SOURCES += sdeventplus/source/time.cpp
 
diff --git a/src/sdeventplus/internal/sdevent.cpp b/src/sdeventplus/internal/sdevent.cpp
index 467a3c3..ad5114c 100644
--- a/src/sdeventplus/internal/sdevent.cpp
+++ b/src/sdeventplus/internal/sdevent.cpp
@@ -244,6 +244,11 @@
     return ::sd_event_source_set_time_accuracy(source, usec);
 }
 
+int SdEventImpl::sd_event_source_get_signal(sd_event_source* source) const
+{
+    return ::sd_event_source_get_signal(source);
+}
+
 SdEventImpl sdevent_impl;
 
 } // namespace internal
diff --git a/src/sdeventplus/internal/sdevent.hpp b/src/sdeventplus/internal/sdevent.hpp
index 62acbbe..42427eb 100644
--- a/src/sdeventplus/internal/sdevent.hpp
+++ b/src/sdeventplus/internal/sdevent.hpp
@@ -25,6 +25,9 @@
                                   uint64_t accuracy,
                                   sd_event_time_handler_t callback,
                                   void* userdata) const = 0;
+    virtual int sd_event_add_signal(sd_event* event, sd_event_source** source,
+                                    int sig, sd_event_signal_handler_t callback,
+                                    void* userdata) const = 0;
     virtual int sd_event_add_defer(sd_event* event, sd_event_source** source,
                                    sd_event_handler_t callback,
                                    void* userdata) const = 0;
@@ -96,6 +99,7 @@
                                                   uint64_t* usec) const = 0;
     virtual int sd_event_source_set_time_accuracy(sd_event_source* source,
                                                   uint64_t usec) const = 0;
+    virtual int sd_event_source_get_signal(sd_event_source*) const = 0;
 };
 
 class SdEventImpl : public SdEvent
@@ -113,6 +117,14 @@
                           clockid_t clock, uint64_t usec, uint64_t accuracy,
                           sd_event_time_handler_t callback,
                           void* userdata) const override;
+
+    int sd_event_add_signal(sd_event* event, sd_event_source** source, int sig,
+                            sd_event_signal_handler_t callback,
+                            void* userdata) const override
+    {
+        return ::sd_event_add_signal(event, source, sig, callback, userdata);
+    }
+
     int sd_event_add_defer(sd_event* event, sd_event_source** source,
                            sd_event_handler_t callback,
                            void* userdata) const override;
@@ -180,6 +192,7 @@
                                           uint64_t* usec) const override;
     int sd_event_source_set_time_accuracy(sd_event_source* source,
                                           uint64_t usec) const override;
+    int sd_event_source_get_signal(sd_event_source*) const override;
 };
 
 extern SdEventImpl sdevent_impl;
diff --git a/src/sdeventplus/source/signal.cpp b/src/sdeventplus/source/signal.cpp
new file mode 100644
index 0000000..1df3a29
--- /dev/null
+++ b/src/sdeventplus/source/signal.cpp
@@ -0,0 +1,52 @@
+#include <sdeventplus/exception.hpp>
+#include <sdeventplus/source/signal.hpp>
+#include <type_traits>
+#include <utility>
+
+namespace sdeventplus
+{
+namespace source
+{
+
+Signal::Signal(const Event& event, int sig, Callback&& callback) :
+    Base(event, create_source(event, sig), std::false_type()),
+    callback(std::move(callback))
+{
+}
+
+int Signal::get_signal() const
+{
+    int r = event.getSdEvent()->sd_event_source_get_signal(source.get());
+    if (r < 0)
+    {
+        throw SdEventError(-r, "sd_event_source_get_signal");
+    }
+    return r;
+}
+
+const Signal::Callback& Signal::get_callback() const
+{
+    return callback;
+}
+
+sd_event_source* Signal::create_source(const Event& event, int sig)
+{
+    sd_event_source* source;
+    int r = event.getSdEvent()->sd_event_add_signal(event.get(), &source, sig,
+                                                    signalCallback, nullptr);
+    if (r < 0)
+    {
+        throw SdEventError(-r, "sd_event_add_signal");
+    }
+    return source;
+}
+
+int Signal::signalCallback(sd_event_source* source,
+                           const struct signalfd_siginfo* si, void* userdata)
+{
+    return sourceCallback<Callback, Signal, &Signal::get_callback>(
+        "signalCallback", source, userdata, si);
+}
+
+} // namespace source
+} // namespace sdeventplus
diff --git a/src/sdeventplus/source/signal.hpp b/src/sdeventplus/source/signal.hpp
new file mode 100644
index 0000000..ec8d227
--- /dev/null
+++ b/src/sdeventplus/source/signal.hpp
@@ -0,0 +1,35 @@
+#pragma once
+
+#include <functional>
+#include <sdeventplus/source/base.hpp>
+#include <sys/signalfd.h>
+
+namespace sdeventplus
+{
+namespace source
+{
+
+class Signal : public Base
+{
+  public:
+    using Callback =
+        std::function<void(Signal& source, const struct signalfd_siginfo* si)>;
+
+    Signal(const Event& event, int sig, Callback&& callback);
+
+    int get_signal() const;
+
+  private:
+    Callback callback;
+
+    const Callback& get_callback() const;
+
+    static sd_event_source* create_source(const Event& event, int sig);
+
+    static int signalCallback(sd_event_source* source,
+                              const struct signalfd_siginfo* si,
+                              void* userdata);
+};
+
+} // namespace source
+} // namespace sdeventplus
diff --git a/src/sdeventplus/test/sdevent.hpp b/src/sdeventplus/test/sdevent.hpp
index 28c484d..37b4464 100644
--- a/src/sdeventplus/test/sdevent.hpp
+++ b/src/sdeventplus/test/sdevent.hpp
@@ -23,6 +23,9 @@
     MOCK_CONST_METHOD7(sd_event_add_time,
                        int(sd_event*, sd_event_source**, clockid_t, uint64_t,
                            uint64_t, sd_event_time_handler_t, void*));
+    MOCK_CONST_METHOD5(sd_event_add_signal,
+                       int(sd_event*, sd_event_source**, int,
+                           sd_event_signal_handler_t, void*));
     MOCK_CONST_METHOD4(sd_event_add_defer, int(sd_event*, sd_event_source**,
                                                sd_event_handler_t, void*));
     MOCK_CONST_METHOD4(sd_event_add_post, int(sd_event*, sd_event_source**,
@@ -83,6 +86,7 @@
                        int(sd_event_source*, uint64_t*));
     MOCK_CONST_METHOD2(sd_event_source_set_time_accuracy,
                        int(sd_event_source*, uint64_t));
+    MOCK_CONST_METHOD1(sd_event_source_get_signal, int(sd_event_source*));
 };
 
 } // namespace test
diff --git a/test/Makefile.am b/test/Makefile.am
index 3d51b65..5a6c1bb 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -47,6 +47,11 @@
 source_io_CPPFLAGS = $(gtest_cppflags)
 source_io_LDADD = $(gtest_ldadd)
 
+check_PROGRAMS += source_signal
+source_signal_SOURCES = source/signal.cpp
+source_signal_CPPFLAGS = $(gtest_cppflags)
+source_signal_LDADD = $(gtest_ldadd)
+
 check_PROGRAMS += source_time
 source_time_SOURCES = source/time.cpp
 source_time_CPPFLAGS = $(gtest_cppflags)
diff --git a/test/source/signal.cpp b/test/source/signal.cpp
new file mode 100644
index 0000000..c99aa6b
--- /dev/null
+++ b/test/source/signal.cpp
@@ -0,0 +1,160 @@
+#include <cerrno>
+#include <functional>
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <memory>
+#include <sdeventplus/event.hpp>
+#include <sdeventplus/exception.hpp>
+#include <sdeventplus/source/signal.hpp>
+#include <sdeventplus/test/sdevent.hpp>
+#include <signal.h>
+#include <systemd/sd-event.h>
+#include <type_traits>
+#include <utility>
+
+namespace sdeventplus
+{
+namespace source
+{
+namespace
+{
+
+using testing::DoAll;
+using testing::Return;
+using testing::SaveArg;
+using testing::SetArgPointee;
+
+using UniqueEvent = std::unique_ptr<Event, std::function<void(Event*)>>;
+
+class SignalTest : public testing::Test
+{
+  protected:
+    testing::StrictMock<test::SdEventMock> mock;
+    sd_event_source* const expected_source =
+        reinterpret_cast<sd_event_source*>(1234);
+    sd_event* const expected_event = reinterpret_cast<sd_event*>(2345);
+    UniqueEvent event = make_event(expected_event);
+
+    UniqueEvent make_event(sd_event* event)
+    {
+        auto deleter = [this, event](Event* e) {
+            EXPECT_CALL(this->mock, sd_event_unref(event))
+                .WillOnce(Return(nullptr));
+            delete e;
+        };
+        return UniqueEvent(new Event(event, std::false_type(), &mock), deleter);
+    }
+
+    void expect_destruct()
+    {
+        {
+            testing::InSequence sequence;
+            EXPECT_CALL(mock, sd_event_source_set_enabled(expected_source,
+                                                          SD_EVENT_OFF))
+                .WillOnce(Return(0));
+            EXPECT_CALL(mock, sd_event_source_unref(expected_source))
+                .WillOnce(Return(nullptr));
+        }
+        EXPECT_CALL(mock, sd_event_unref(expected_event))
+            .WillOnce(Return(nullptr));
+    }
+};
+
+TEST_F(SignalTest, ConstructSuccess)
+{
+    const int sig = SIGALRM;
+
+    EXPECT_CALL(mock, sd_event_ref(expected_event))
+        .WillOnce(Return(expected_event));
+    sd_event_signal_handler_t handler;
+    EXPECT_CALL(mock, sd_event_add_signal(expected_event, testing::_, sig,
+                                          testing::_, nullptr))
+        .WillOnce(DoAll(SetArgPointee<1>(expected_source), SaveArg<3>(&handler),
+                        Return(0)));
+    void* userdata;
+    EXPECT_CALL(mock, sd_event_source_set_userdata(expected_source, testing::_))
+        .WillOnce(DoAll(SaveArg<1>(&userdata), Return(nullptr)));
+    int completions = 0;
+    const struct signalfd_siginfo* return_si;
+    Signal::Callback callback = [&](Signal&,
+                                    const struct signalfd_siginfo* si) {
+        return_si = si;
+        completions++;
+    };
+    Signal signal(*event, sig, std::move(callback));
+    EXPECT_FALSE(callback);
+    EXPECT_EQ(&signal, userdata);
+    EXPECT_EQ(0, completions);
+
+    const struct signalfd_siginfo* expected_si =
+        reinterpret_cast<struct signalfd_siginfo*>(865);
+    EXPECT_EQ(0, handler(nullptr, expected_si, &signal));
+    EXPECT_EQ(1, completions);
+    EXPECT_EQ(expected_si, return_si);
+
+    expect_destruct();
+}
+
+TEST_F(SignalTest, ConstructError)
+{
+    const int sig = SIGALRM;
+
+    EXPECT_CALL(mock, sd_event_add_signal(expected_event, testing::_, sig,
+                                          testing::_, nullptr))
+        .WillOnce(Return(-EINVAL));
+    int completions = 0;
+    Signal::Callback callback = [&completions](Signal&,
+                                               const struct signalfd_siginfo*) {
+        completions++;
+    };
+    EXPECT_THROW(Signal(*event, sig, std::move(callback)), SdEventError);
+    EXPECT_TRUE(callback);
+    EXPECT_EQ(0, completions);
+}
+
+class SignalMethodTest : public SignalTest
+{
+  protected:
+    std::unique_ptr<Signal> signal;
+
+    void SetUp()
+    {
+        const int sig = SIGINT;
+
+        EXPECT_CALL(mock, sd_event_ref(expected_event))
+            .WillOnce(Return(expected_event));
+        EXPECT_CALL(mock, sd_event_add_signal(expected_event, testing::_, sig,
+                                              testing::_, nullptr))
+            .WillOnce(DoAll(SetArgPointee<1>(expected_source), Return(0)));
+        EXPECT_CALL(mock,
+                    sd_event_source_set_userdata(expected_source, testing::_))
+            .WillOnce(Return(nullptr));
+        signal = std::make_unique<Signal>(
+            *event, sig, [](Signal&, const struct signalfd_siginfo*) {});
+    }
+
+    void TearDown()
+    {
+        expect_destruct();
+        signal.reset();
+    }
+};
+
+TEST_F(SignalMethodTest, GetSignalSuccess)
+{
+    const int sig = SIGTERM;
+    EXPECT_CALL(mock, sd_event_source_get_signal(expected_source))
+        .WillOnce(Return(sig));
+    EXPECT_EQ(sig, signal->get_signal());
+}
+
+TEST_F(SignalMethodTest, GetSignalError)
+{
+    EXPECT_CALL(mock, sd_event_source_get_signal(expected_source))
+        .WillOnce(Return(-EINVAL));
+    EXPECT_THROW(signal->get_signal(), SdEventError);
+}
+
+} // namespace
+} // namespace source
+} // namespace sdeventplus