source/base: Refactor out callback routine

The callback mechanism will be used by other callback methods in the
same fashion, so we can template and re-use this functionality

3 files changed, 39 insertions, 29 deletions

diff --git a/src/sdeventplus/internal/utils.hpp b/src/sdeventplus/internal/utils.hpp
index 253e10d..c0b0e68 100644
--- a/src/sdeventplus/internal/utils.hpp
+++ b/src/sdeventplus/internal/utils.hpp
@@ -1,6 +1,11 @@
 #pragma once
 
+#include <cerrno>
 #include <chrono>
+#include <cstdio>
+#include <exception>
+#include <sdeventplus/exception.hpp>
+#include <stdexcept>
 
 namespace sdeventplus
 {
@@ -9,4 +14,34 @@ namespace sdeventplus
 using SdEventDuration =
     std::chrono::duration<uint64_t, std::chrono::microseconds::period>;
 
+namespace internal
+{
+
+// Helpers for sd_event callbacks to handle exceptions gracefully
+template <typename Func, typename... Args>
+static int performCallback(Func func, Args... args)
+{
+    try
+    {
+        func(args...);
+        return 0;
+    }
+    catch (const std::system_error& e)
+    {
+        fprintf(stderr, "sdeventplus: callback: %s\n", e.what());
+        return -e.code().value();
+    }
+    catch (const std::exception& e)
+    {
+        fprintf(stderr, "sdeventplus: callback: %s\n", e.what());
+        return -ENOSYS;
+    }
+    catch (...)
+    {
+        fprintf(stderr, "sdeventplus: callback: Unknown error\n");
+        return -ENOSYS;
+    }
+}
+
+} // namespace internal
 } // namespace sdeventplus
diff --git a/src/sdeventplus/source/base.cpp b/src/sdeventplus/source/base.cpp
index 83908d1..5f202db 100644
--- a/src/sdeventplus/source/base.cpp
+++ b/src/sdeventplus/source/base.cpp
@@ -1,10 +1,10 @@
 #include <cerrno>
 #include <cstdio>
-#include <exception>
+#include <functional>
 #include <sdeventplus/exception.hpp>
 #include <sdeventplus/internal/sdevent.hpp>
+#include <sdeventplus/internal/utils.hpp>
 #include <sdeventplus/source/base.hpp>
-#include <stdexcept>
 #include <type_traits>
 #include <utility>
 
@@ -21,30 +21,6 @@ Base::~Base()
     }
 }
 
-int Base::prepareCallback()
-{
-    try
-    {
-        prepare(*this);
-        return 0;
-    }
-    catch (const std::system_error& e)
-    {
-        fprintf(stderr, "sdeventplus: prepareCallback: %s\n", e.what());
-        return -e.code().value();
-    }
-    catch (const std::exception& e)
-    {
-        fprintf(stderr, "sdeventplus: prepareCallback: %s\n", e.what());
-        return -ENOSYS;
-    }
-    catch (...)
-    {
-        fprintf(stderr, "sdeventplus: prepareCallback: Unknown error\n");
-        return -ENOSYS;
-    }
-}
-
 sd_event_source* Base::get() const
 {
     return source.get();
@@ -84,7 +60,8 @@ static int prepare_callback(sd_event_source*, void* userdata)
         fprintf(stderr, "sdeventplus: prepare_callback: Missing userdata\n");
         return -EINVAL;
     }
-    return reinterpret_cast<Base*>(userdata)->prepareCallback();
+    Base* base = reinterpret_cast<Base*>(userdata);
+    return internal::performCallback(base->get_prepare(), std::ref(*base));
 }
 
 void Base::set_prepare(Callback&& callback)
diff --git a/src/sdeventplus/source/base.hpp b/src/sdeventplus/source/base.hpp
index ed30016..9253b71 100644
--- a/src/sdeventplus/source/base.hpp
+++ b/src/sdeventplus/source/base.hpp
@@ -19,8 +19,6 @@ class Base
 
     virtual ~Base();
 
-    int prepareCallback();
-
     sd_event_source* get() const;
     const Event& get_event() const;