Implement support for attaching GDB to the Icinga process on crash

fixes #9866

doc/19-language-reference.md

@@ -375,6 +375,7 @@ EnableHostChecks    |**Read-write.** Whether active host checks are globally ena
 EnableServiceChecks |**Read-write.** Whether active service checks are globally enabled. Defaults to true.
 EnablePerfdata      |**Read-write.** Whether performance data processing is globally enabled. Defaults to true.
 UseVfork            |**Read-write.** Whether to use vfork(). Only available on *NIX. Defaults to true.
+AttachDebugger      |**Read-write.** Whether to attach a debugger when Icinga 2 crashes. Defaults to false.
 RunAsUser	        |**Read-write.** Defines the user the Icinga 2 daemon is running as. Used in the `init.conf` configuration file.
 RunAsGroup	        |**Read-write.** Defines the group the Icinga 2 daemon is running as. Used in the `init.conf` configuration file.
 

icinga-app/icinga.cpp

@@ -173,6 +173,8 @@ int Main(void)
 		ScriptGlobal::Set("UseVfork", true);
 #endif /* __APPLE__ */
 
+	ScriptGlobal::Set("AttachDebugger", false);
+
 	LogSeverity logLevel = Logger::GetConsoleLogSeverity();
 	Logger::SetConsoleLogSeverity(LogWarning);
 

lib/base/application.cpp

@@ -626,9 +626,9 @@ String Application::GetCrashReportFilename(void)
 }
 
 
-#ifndef _WIN32
-void Application::GetDebuggerBacktrace(const String& filename)
+void Application::AttachDebugger(const String& filename, bool interactive)
 {
+#ifndef _WIN32
 #ifdef __linux__
 	prctl(PR_SET_DUMPABLE, 1);
 #endif /* __linux __ */
@@ -644,6 +644,7 @@ void Application::GetDebuggerBacktrace(const String& filename)
 	}
 
 	if (pid == 0) {
+		if (!interactive) {
 			int fd = open(filename.CStr(), O_CREAT | O_RDWR | O_APPEND, 0600);
 
 			if (fd < 0) {
@@ -664,9 +665,21 @@ void Application::GetDebuggerBacktrace(const String& filename)
 				close(2);
 
 			dup2(1, 2);
+		}
 
+		char **argv;
 		char *my_pid_str = strdup(my_pid.CStr());
-		const char *argv[] = {
+
+		if (interactive) {
+			const char *uargv[] = {
+				"gdb",
+				"-p",
+				my_pid_str,
+				NULL
+			};
+			argv = const_cast<char **>(uargv);
+		} else {
+			const char *uargv[] = {
 				"gdb",
 				"--batch",
 				"-p",
@@ -679,7 +692,10 @@ void Application::GetDebuggerBacktrace(const String& filename)
 				"quit",
 				NULL
 			};
-		(void)execvp(argv[0], const_cast<char **>(argv));
+			argv = const_cast<char **>(uargv);
+		}
+
+		(void)execvp(argv[0], argv);
 		perror("Failed to launch GDB");
 		free(my_pid_str);
 		_exit(0);
@@ -695,6 +711,9 @@ void Application::GetDebuggerBacktrace(const String& filename)
 #ifdef __linux__
 	prctl(PR_SET_DUMPABLE, 0);
 #endif /* __linux __ */
+#else /* _WIN32 */
+	DebugBreak();
+#endif /* _WIN32 */
 }
 
 /**
@@ -750,6 +769,9 @@ void Application::SigAbrtHandler(int)
 	String fname = GetCrashReportFilename();
 	Utility::MkDir(Utility::DirName(fname), 0750);
 
+	bool interactive_debugger = Convert::ToBool(ScriptGlobal::Get("AttachDebugger"));
+
+	if (!interactive_debugger) {
 		std::ofstream ofs;
 		ofs.open(fname.CStr());
 
@@ -764,16 +786,16 @@ void Application::SigAbrtHandler(int)
 
 		DisplayBugMessage(ofs);
 
-#ifndef _WIN32
 		ofs << "\n";
 		ofs.close();
+	} else {
+		Log(LogCritical, "Application", "Icinga 2 has terminated unexpeectedly. Attaching debugger...");
+	}
 
-	GetDebuggerBacktrace(fname);
-#else /* _WIN32 */
-	ofs.close();
-#endif /* _WIN32 */
+	AttachDebugger(fname, interactive_debugger);
 }
-#else /* _WIN32 */
+
+#ifdef _WIN32
 /**
  * Console control handler. Prepares the application for cleanly
  * shutting down during the next execution of the event loop.
@@ -813,6 +835,9 @@ void Application::ExceptionHandler(void)
 	String fname = GetCrashReportFilename();
 	Utility::MkDir(Utility::DirName(fname), 0750);
 
+	bool interactive_debugger = Convert::ToBool(ScriptGlobal::Get("AttachDebugger"));
+
+	if (interactive_debugger) {
 		std::ofstream ofs;
 		ofs.open(fname.CStr());
 
@@ -838,10 +863,9 @@ void Application::ExceptionHandler(void)
 		DisplayBugMessage(ofs);
 
 		ofs.close();
+	}
 
-#ifndef _WIN32
-	GetDebuggerBacktrace(fname);
-#endif /* _WIN32 */
+	AttachDebugger(fname, interactive_debugger);
 
 	abort();
 }

lib/base/application.hpp

@@ -175,9 +175,7 @@ private:
 
 	static String GetCrashReportFilename(void);
 
-#ifndef _WIN32
-	static void GetDebuggerBacktrace(const String& filename);
-#endif /* _WIN32 */
+	static void AttachDebugger(const String& filename, bool interactive);
 };
 
 }