server, debug: Fancier backtraces

src/impl/linux/debug.cpp

@@ -8,6 +8,7 @@
 #include <atomic>
 #include <cstdlib>
 #include <cstring>
+#include <cstdarg>
 #include <execinfo.h>
 #include <signal.h>
 #include <sys/ucontext.h>
@@ -67,7 +68,7 @@ static void* get_library_executable_address(const ss_ &lib_path)
 	#define REG_EIP REG_RIP
 #endif
 
-static void log_backtrace(void* const *trace, int trace_size);
+static void log_backtrace(void* const *trace, int trace_size, const ss_ &title);
 
 static void debug_sighandler(int sig, siginfo_t *info, void *secret)
 {
@@ -84,7 +85,7 @@ static void debug_sighandler(int sig, siginfo_t *info, void *secret)
 	// Overwrite sigaction with caller's address
 	trace[1] = (void*) uc->uc_mcontext.gregs[REG_EIP];
 
-	log_backtrace(trace, trace_size);
+	log_backtrace(trace, trace_size, "Backtrace for signal:");
 
 	exit(1);
 }
@@ -103,8 +104,25 @@ void init_signal_handlers(const SigConfig &config)
 }
 
 static std::atomic_int log_backtrace_spinlock(0);
+static char backtrace_buffer[10000];
+static size_t backtrace_buffer_len = 0;
 
-static void log_backtrace(void* const *trace, int trace_size)
+static void bt_print(const char *fmt, ...)
+{
+	va_list va_args;
+	va_start(va_args, fmt);
+	backtrace_buffer_len += vsnprintf(
+			backtrace_buffer + backtrace_buffer_len,
+			sizeof backtrace_buffer - backtrace_buffer_len,
+			fmt, va_args);
+	va_end(va_args);
+	backtrace_buffer_len += snprintf(
+			backtrace_buffer + backtrace_buffer_len,
+			sizeof backtrace_buffer - backtrace_buffer_len,
+			"\n");
+}
+
+static void log_backtrace(void* const *trace, int trace_size, const ss_ &title)
 {
 	char **symbols = backtrace_symbols(trace, trace_size);
 
@@ -117,7 +135,8 @@ static void log_backtrace(void* const *trace, int trace_size)
 	}
 
 	// The first stack frame points to this functiton
-	log_i(MODULE, "Backtrace:");
+	backtrace_buffer_len = 0;
+	bt_print("\n  %s", cs(title));
 	for(int i = 1; i < trace_size; i++){
 		char cmdbuf[500];
 		// Parse symbol to get file name
@@ -146,23 +165,27 @@ static void log_backtrace(void* const *trace, int trace_size)
 		ss_ addr2line_output = exec_get_stdout_without_newline(cmdbuf);
 
 		if(addr2line_output.size() > 4){
-			log_i(MODULE, "#%i  %s", i-1, cs(addr2line_output));
+			bt_print("    #%i  %s", i-1, cs(addr2line_output));
 			log_d(MODULE, "    = %s", cs(cppfilt_symbol));
 		} else {
-			log_i(MODULE, "#%i  %s", i-1, cs(cppfilt_symbol));
+			bt_print("    #%i  %s", i-1, cs(cppfilt_symbol));
 		}
 	}
 
+	// Print to log
+	backtrace_buffer[sizeof backtrace_buffer - 1] = 0;
+	log_i(MODULE, "%s", backtrace_buffer);
+
 	// Unlock spinlock
 	log_backtrace_spinlock--;
 }
 
-void log_current_backtrace()
+void log_current_backtrace(const ss_ &title)
 {
 	void *trace[16];
 	int trace_size = backtrace(trace, 16);
 
-	log_backtrace(trace, trace_size);
+	log_backtrace(trace, trace_size, title);
 }
 
 #include <cxxabi.h>
@@ -196,9 +219,9 @@ extern "C" {
 	}
 }
 
-void log_exception_backtrace()
+void log_exception_backtrace(const ss_ &title)
 {
-	log_backtrace(last_exception_frames, last_exception_num_frames);
+	log_backtrace(last_exception_frames, last_exception_num_frames, title);
 }
 
 }

src/impl/thread.cpp

@@ -85,7 +85,10 @@ struct CThread: public Thread
 		} catch(std::exception &e){
 			log_w(MODULE, "ThreadThing of thread %p (%s) failed: %s",
 					arg, cs(thread_name), e.what());
-			interface::debug::log_exception_backtrace();
+			interface::debug::log_exception_backtrace(
+					"Backtrace for ThreadThing("+thread_name+"):");
+			/*interface::debug::log_current_backtrace(
+					"Backtrace for ThreadThing("+thread_name+") (current):");*/
 		}
 
 		log_d(MODULE, "Thread %p (%s) exit", arg, cs(thread_name));

src/impl/windows/debug.cpp

@@ -12,12 +12,12 @@ void init_signal_handlers(const SigConfig &config)
 	// No-op
 }
 
-void log_current_backtrace()
+void log_current_backtrace(const ss_ &title)
 {
 	log_i(MODULE, "Backtrace logging not implemented on Windows");
 }
 
-void log_exception_backtrace()
+void log_exception_backtrace(const ss_ &title)
 {
 	log_i(MODULE, "Backtrace logging not implemented on Windows");
 }

src/interface/debug.h

@@ -14,9 +14,9 @@ namespace interface
 
 		void init_signal_handlers(const SigConfig &config);
 
-		void log_current_backtrace();
+		void log_current_backtrace(const ss_ &title="Current backtrace:");
 
-		void log_exception_backtrace();
+		void log_exception_backtrace(const ss_ &title="Exception backtrace:");
 	}
 }
 // vim: set noet ts=4 sw=4:

src/server/state.cpp

@@ -193,6 +193,8 @@ struct ModuleContainer
 		if(eptr){
 			log_t(MODULE, "execute_direct_cb[%s]: Execution finished by"
 					" exception", cs(info.name));
+			/*interface::debug::log_current_backtrace(
+					"Backtrace for M["+info.name+"]'s caller:");*/
 			std::rethrow_exception(eptr);
 		} else {
 			log_t(MODULE, "execute_direct_cb[%s]: Execution finished",
@@ -290,7 +292,8 @@ void ModuleThread::run(interface::Thread *thread)
 							cs(mc->info.name), e.what());
 					// If event handling results in an uncatched exception, the
 					// server shall shut down.
-					interface::debug::log_exception_backtrace();
+					interface::debug::log_exception_backtrace(
+							"Backtrace for M["+mc->info.name+"]->event():");
 					mc->server->shutdown(1, "M["+mc->info.name+"]->event() "
 							"failed: "+e.what());
 				}