feat: Support for ignored signals with SIGN_IGN (#1489)

Currently, if a signal is ignored via SIG_IGN (which is especially common for signals like SIGPIPE), Sentry will still report a fatal, unhandled crash even though the application never received the signal and continued to run just fine. This PR fixes this behavior by only setting a signal handler to report a crash from signal if the original handler is NOT SIG_IGN. Fixes GH-1472 Co-authored-by: Philipp Hofmann <[email protected]>
getsentry · Dec 2, 2021 · 0b468b8 · 0b468b8
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ## 7.5.4
 
 - fix: Sending OOM when SDK is closed (#1487)
+- feat: Don't mark a signal as a crash if the signal was ignored via `SIG_IGN` (#1489)
 
 ## 7.5.3
 

diff --git a/Sources/SentryCrash/Recording/Monitors/SentryCrashMonitor_Signal.c b/Sources/SentryCrash/Recording/Monitors/SentryCrashMonitor_Signal.c
@@ -175,6 +175,13 @@ installSignalHandler()
                 sigaction(fatalSignals[i], &g_previousSignalHandlers[i], NULL);
             }
             goto failed;
+        } else {
+            // The previous handler was `SIG_IGN` -- restore the original handler so
+            // we don't override the `SIG_IGN` and report a crash when the application
+            // would have ignored the signal otherwise.
+            if (g_previousSignalHandlers[i].sa_handler == SIG_IGN) {
+                sigaction(fatalSignals[i], &g_previousSignalHandlers[i], NULL);
+            }
         }
     }
     SentryCrashLOG_DEBUG("Signal handlers installed.");