added --catch-exceptions, it will print app exceptions to your browser

ini.c

@@ -131,7 +131,7 @@ void uwsgi_ini_config(char *file, struct option *long_options) {
 			if (key[0] == '[') {
 				section = key;
 			}
-			else if (key[0] == ';') {
+			else if (key[0] == ';' || key[0] == '#') {
 				// this is a comment
 			}
 			else {

pyutils.c

@@ -160,13 +160,15 @@ clear2:
 }
 
 
-PyObject *python_call(PyObject *callable, PyObject *args) {
+PyObject *python_call(PyObject *callable, PyObject *args, int catch) {
 	
 	PyObject *pyret;
 
 	pyret =  PyEval_CallObject(callable, args);
 	if (PyErr_Occurred()) {
-		PyErr_Print();
+		if (!catch) { 
+			PyErr_Print();
+		}
 	}
 
 #ifdef UWSGI_DEBUG
@@ -183,7 +185,7 @@ PyObject *python_call(PyObject *callable, PyObject *args) {
 
 int uwsgi_python_call(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req, PyObject *callable, PyObject *args) {
 	
-	wsgi_req->async_result = python_call(callable, args);
+	wsgi_req->async_result = python_call(callable, args, 0);
 
 	if (wsgi_req->async_result) {
 		while ( manage_python_response(uwsgi, wsgi_req) != UWSGI_OK) {

spooler.c

@@ -249,7 +249,7 @@ void spooler(struct uwsgi_server *uwsgi, PyObject * uwsgi_module_dict) {
 						}
 
 
-						spool_result = python_call(spooler_callable, spool_tuple);
+						spool_result = python_call(spooler_callable, spool_tuple, 0);
 						if (!spool_result) {
 							PyErr_Print();
 							uwsgi_log( "error detected. spool request canceled.\n");

uwsgi.c

@@ -395,6 +395,7 @@ int main(int argc, char *argv[], char *envp[]) {
 		{"http", required_argument, 0, LONG_ARGS_HTTP},
 		{"http-only", no_argument, &uwsgi.http_only, 1},
 #endif
+		{"catch-exceptions", no_argument, &uwsgi.catch_exceptions, 1},
 		{"mode", required_argument, 0, LONG_ARGS_MODE},
 		{"env", required_argument, 0, LONG_ARGS_ENV},
 		{"version", no_argument, 0, LONG_ARGS_MODE},
@@ -1262,7 +1263,7 @@ int main(int argc, char *argv[], char *envp[]) {
 										PyTuple_SetItem(udp_callable_args, 0, PyString_FromString(udp_client_addr));
 										PyTuple_SetItem(udp_callable_args, 1, PyInt_FromLong(ntohs(udp_client.sin_port)));
 										PyTuple_SetItem(udp_callable_args, 2, PyString_FromStringAndSize(uwsgi.wsgi_req->buffer, rlen));
-										PyObject *udp_response = python_call(udp_callable, udp_callable_args);
+										PyObject *udp_response = python_call(udp_callable, udp_callable_args, 0);
 										if (udp_response) {
 											Py_DECREF(udp_response);
 										}

uwsgi.h

@@ -653,6 +653,7 @@ struct uwsgi_server {
 #endif
 
 	char *chdir2;
+	int catch_exceptions;
 };
 
 struct uwsgi_cluster_node {
@@ -923,7 +924,7 @@ PyObject *py_uwsgi_stackless(PyObject *, PyObject *) ;
 
 int manage_python_response(struct uwsgi_server *, struct wsgi_request *);
 int uwsgi_python_call(struct uwsgi_server *, struct wsgi_request *, PyObject *, PyObject *);
-PyObject *python_call(PyObject *, PyObject *);
+PyObject *python_call(PyObject *, PyObject *, int);
 
 #ifdef UWSGI_SENDFILE
 PyObject *py_uwsgi_sendfile(PyObject *, PyObject *) ;

uwsgiconfig.py

@@ -314,7 +314,7 @@ def parse_vars():
 		else:
 			libs.append(pcreconf)
 
-	if EVDIS:
+	if HTTP:
 		cflags.append("-DUWSGI_HTTP")
 		gcc_list.append('http')
 

wsgi_handlers.c

@@ -352,7 +352,7 @@ int uwsgi_request_wsgi(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req
 #ifdef UWSGI_PROFILER
 	if (uwsgi->enable_profiler == 1) {
 		PyDict_SetItem(wi->pymain_dict, PyString_FromFormat("uwsgi_environ__%d", wsgi_req->app_id), wsgi_req->async_environ);
-		wsgi_req->async_result = python_call(wi->wsgi_cprofile_run, wsgi_req->async_args);
+		wsgi_req->async_result = python_call(wi->wsgi_cprofile_run, wsgi_req->async_args, 0);
 		if (wsgi_req->async_result) {
 			wsgi_req->async_result = PyDict_GetItemString(wi->pymain_dict, "uwsgi_out");
 			Py_INCREF((PyObject*)wsgi_req->async_result);
@@ -364,7 +364,7 @@ int uwsgi_request_wsgi(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req
 
 
 		PyTuple_SetItem(wsgi_req->async_args, 0, wsgi_req->async_environ);
-		wsgi_req->async_result = python_call(wsgi_req->async_app, wsgi_req->async_args);
+		wsgi_req->async_result = python_call(wsgi_req->async_app, wsgi_req->async_args, uwsgi->catch_exceptions);
 
 #ifdef UWSGI_PROFILER
 	}
@@ -384,6 +384,36 @@ int uwsgi_request_wsgi(struct uwsgi_server *uwsgi, struct wsgi_request *wsgi_req
 
 
 	}
+	else if (uwsgi->catch_exceptions) {
+
+		wsgi_req->response_size += write(wsgi_req->poll.fd, wsgi_req->protocol, wsgi_req->protocol_len);
+		wsgi_req->response_size += write(wsgi_req->poll.fd, " 500 Internal Server Error\r\n", 28 );
+		wsgi_req->response_size += write(wsgi_req->poll.fd, "Content-type: text/plain\r\n\r\n", 28 );
+		wsgi_req->header_cnt = 1 ;
+		
+		/* 
+			sorry that is a hack to avoid the rewrite of PyErr_Print
+			temporarily map (using dup2) stderr to wsgi_req->poll.fd
+		*/
+		int tmp_stderr = dup(2);
+		if (tmp_stderr < 0) {
+			uwsgi_error("dup()");
+			goto clear;
+		}
+		// map 2 to wsgi_req
+		if (dup2(wsgi_req->poll.fd, 2) < 0) {
+			close(tmp_stderr);
+			uwsgi_error("dup2()");
+			goto clear;
+		}
+		// print the error
+		PyErr_Print();
+		// ...resume the original stderr, in case of error we are damaged forever !!!
+		if (dup2(tmp_stderr, 2) < 0) {
+			uwsgi_error("dup2()");
+		}
+		close(tmp_stderr);	
+	}
 
 clear: