From 69f975c05a5df201375fdef9bef88282cc2d7fbb Mon Sep 17 00:00:00 2001
From: magiblot <magiblot@hotmail.com>
Date: Sun, 15 Oct 2023 23:57:54 +0200
Subject: [PATCH] platform: handle SIG_IGN properly in SignalHandler

---
 source/platform/sighandl.cpp    | 12 ++++++++++--
 test/platform/sighandl.test.cpp | 12 ++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/source/platform/sighandl.cpp b/source/platform/sighandl.cpp
index bf8b839b..855dcb91 100644
--- a/source/platform/sighandl.cpp
+++ b/source/platform/sighandl.cpp
@@ -98,15 +98,23 @@ void SignalHandler::handleSignal(int signo, siginfo_t *info, void *context)
     }
 }
 
+template <class T>
+static inline bool isCustomHandler(T &&handler)
+{
+    return (void *) handler != (void *) SIG_DFL
+        && (void *) handler != (void *) SIG_IGN;
+}
+
 bool SignalHandler::invokeHandlerOrDefault( int signo, const struct sigaction &action,
                                             siginfo_t *info, void *context ) noexcept
 {
     // If the handler is a custom one, invoke it directly.
-    if ((action.sa_flags & SA_SIGINFO) && action.sa_sigaction)
+    if ((action.sa_flags & SA_SIGINFO) && isCustomHandler(action.sa_sigaction))
         action.sa_sigaction(signo, info, context);
-    else if (!(action.sa_flags & SA_SIGINFO) && action.sa_handler)
+    else if (!(action.sa_flags & SA_SIGINFO) && isCustomHandler(action.sa_handler))
         action.sa_handler(signo);
     else
+        // Run default handler by re-raising the signal.
         return invokeDefault(signo, info);
     return false;
 }
diff --git a/test/platform/sighandl.test.cpp b/test/platform/sighandl.test.cpp
index ed7850e6..bcbd2e7f 100644
--- a/test/platform/sighandl.test.cpp
+++ b/test/platform/sighandl.test.cpp
@@ -158,6 +158,18 @@ TEST_F(SignalHandlerTest, ShouldOnlyInvokeCallbackOnEnterWhenSignalKillsTheProce
     ASSERT_EQ(counters->callbackExitInvocations, 0);
 }
 
+TEST_F(SignalHandlerTest, ShouldInvokeCallbackOnEnterAndExitWhenSignalIsIgnored)
+{
+    installSignalHandler(SIGINT, SIG_IGN);
+    SignalHandler::enable(signalCallbackThatTemporarilyDisablesSignalHandler);
+    for (int i = 1; i <= 2; ++i)
+    {
+        ASSERT_NE(raise(SIGINT), -1);
+        ASSERT_EQ(counters->callbackEnterInvocations, i);
+        ASSERT_EQ(counters->callbackExitInvocations, i);
+    }
+}
+
 TEST_F(SignalHandlerTest, ShouldFallBackToDefaultHandlerWhenCallbackAborts)
 {
     installSignalHandler(SIGABRT, signalHandlerThatDoesNotKillTheProcess);