Always emit scripting errors to stderr during zeek_init

Otherwise, setting Reporter::errors_to_stderr=F causes important
error messages to be lost (and this setting is the default for
ZeekCtl).  E.g. now that we terminate if there's errors during
zeek_init, GH-369 shows that the only error message given was
"fatal error: errors occurred while initializing", which is not
helpful in determining the actual issue.

CHANGES

@@ -1,4 +1,8 @@
 
+2.6-308 | 2019-05-17 14:13:46 -0700
+
+  * Always emit scripting errors to stderr during zeek_init (Jon Siwek, Corelight)
+
 2.6-307 | 2019-05-16 13:37:24 -0700
 
   * More bro-to-zeek renaming in scripts and other files (Daniel Thayer)

VERSION

@@ -1 +1 @@
-2.6-307
+2.6-308

src/Reporter.cc

@@ -31,12 +31,14 @@ Reporter::Reporter()
 	via_events = false;
 	in_error_handler = 0;
 
-	// Always use stderr at startup/init before scripts have been fully parsed.
+	// Always use stderr at startup/init before scripts have been fully parsed
+	// and zeek_init() processed.
 	// Messages may otherwise be missed if an error occurs that prevents events
 	// from ever being dispatched.
 	info_to_stderr = true;
 	warnings_to_stderr = true;
 	errors_to_stderr = true;
+	after_zeek_init = false;
 
 	weird_count = 0;
 	weird_sampling_rate = 0;
@@ -80,7 +82,7 @@ void Reporter::Info(const char* fmt, ...)
 	{
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = info_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(info_to_stderr) ? stderr : 0;
 	DoLog("", reporter_info, out, 0, 0, true, true, 0, fmt, ap);
 	va_end(ap);
 	}
@@ -89,7 +91,7 @@ void Reporter::Warning(const char* fmt, ...)
 	{
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = warnings_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(warnings_to_stderr) ? stderr : 0;
 	DoLog("warning", reporter_warning, out, 0, 0, true, true, 0, fmt, ap);
 	va_end(ap);
 	}
@@ -99,7 +101,7 @@ void Reporter::Error(const char* fmt, ...)
 	++errors;
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = errors_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(errors_to_stderr) ? stderr : 0;
 	DoLog("error", reporter_error, out, 0, 0, true, true, 0, fmt, ap);
 	va_end(ap);
 	}
@@ -142,7 +144,7 @@ void Reporter::ExprRuntimeError(const Expr* expr, const char* fmt, ...)
 	PushLocation(expr->GetLocationInfo());
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = errors_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(errors_to_stderr) ? stderr : 0;
 	DoLog("expression error", reporter_error, out, 0, 0, true, true,
 	      d.Description(), fmt, ap);
 	va_end(ap);
@@ -156,7 +158,7 @@ void Reporter::RuntimeError(const Location* location, const char* fmt, ...)
 	PushLocation(location);
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = errors_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(errors_to_stderr) ? stderr : 0;
 	DoLog("runtime error", reporter_error, out, 0, 0, true, true, "", fmt, ap);
 	va_end(ap);
 	PopLocation();
@@ -196,7 +198,7 @@ void Reporter::InternalWarning(const char* fmt, ...)
 	{
 	va_list ap;
 	va_start(ap, fmt);
-	FILE* out = warnings_to_stderr ? stderr : 0;
+	FILE* out = EmitToStderr(warnings_to_stderr) ? stderr : 0;
 	// TODO: would be nice to also log a call stack.
 	DoLog("internal warning", reporter_warning, out, 0, 0, true, true, 0, fmt,
 	      ap);

src/Reporter.h

@@ -233,6 +233,13 @@ public:
 		this->weird_sampling_duration = weird_sampling_duration;
 		}
 
+	/**
+	 * Called after zeek_init() and toggles whether messages may stop being
+	 * emitted to stderr.
+	 */
+	void ZeekInitDone()
+		{ after_zeek_init = true; }
+
 private:
 	void DoLog(const char* prefix, EventHandlerPtr event, FILE* out,
 		   Connection* conn, val_list* addl, bool location, bool time,
@@ -248,12 +255,16 @@ private:
 	bool PermitNetWeird(const char* name);
 	bool PermitFlowWeird(const char* name, const IPAddr& o, const IPAddr& r);
 
+	bool EmitToStderr(bool flag)
+		{ return flag || ! after_zeek_init; }
+
 	int errors;
 	bool via_events;
 	int in_error_handler;
 	bool info_to_stderr;
 	bool warnings_to_stderr;
 	bool errors_to_stderr;
+	bool after_zeek_init;
 
 	std::list<std::pair<const Location*, const Location*> > locations;
 

src/main.cc

@@ -1087,6 +1087,7 @@ int main(int argc, char** argv)
 		reporter->FatalError("errors occurred while initializing");
 
 	broker_mgr->ZeekInitDone();
+	reporter->ZeekInitDone();
 	analyzer_mgr->DumpDebug();
 
 	have_pending_timers = ! reading_traces && timer_mgr->Size() > 0;

testing/btest/scripts/base/frameworks/reporter/disable-stderr.zeek

@@ -7,7 +7,14 @@ redef Reporter::errors_to_stderr = F;
 
 global test: table[count] of string = {};
 
-event zeek_init()
+event my_event()
 	{
 	print test[3];
 	}
+
+event zeek_init()
+	{
+	# Errors within zeek_init are always printed to stderr, so check whether
+	# an error that happens later is suppressed.
+	schedule 0.2sec { my_event() };
+	}