Add q3py logging functions

Add q3py_log() and q3py_error() functions in preparation for issue #9

src/q3py.c

@@ -26,6 +26,15 @@ static syscallptr *q3_syscall = NULL;
 static PyObject *q3py_vmMain = NULL;
 
 
+static void q3py_log(const char* message) {
+	fprintf(stdout, "Q3PY: %s\n", message);
+}
+
+static void q3py_error(const char* message) {
+	fprintf(stderr, "Q3PY: %s\n", message);
+}
+
+
 /**
  * Tries to finalize Python, then exits.
  */
@@ -102,7 +111,7 @@ PyObject* PyInit_q3py() {
 
 	PyObject *module = PyModule_Create(&q3pymodule);
 	if (NULL == module) {
-		fprintf(stderr, "Failed to create module\n");
+		q3py_error("Failed to create module '" Q3PY_MODULE_NAME "'");
 		return NULL;
 	}
 
@@ -112,13 +121,14 @@ PyObject* PyInit_q3py() {
 	PyObject *capsule = PyCapsule_New((void *)Q3Py_API, Q3PY_MODULE_NAME "." Q3PY_CAPI_CAPSULE_NAME, NULL);
 	if (capsule != NULL) {
 		if (-1 == PyModule_AddObject(module, Q3PY_CAPI_CAPSULE_NAME, capsule)) {
-			fprintf(stderr, "Failed to add capsule to module\n");
+			q3py_error("Failed to add capsule '" Q3PY_CAPI_CAPSULE_NAME "' "
+			           "to module '" Q3PY_MODULE_NAME "'");
 			return NULL;
 		}
 	}
 	else {
 		PyErr_Print();
-		fprintf(stderr, "Could not create capsule\n");
+		q3py_error("Could not create capsule");
 		return NULL;
 	}
 
@@ -134,7 +144,7 @@ PyObject* PyInit_q3py() {
  */
 void check_vmMainPy() {
 	if (NULL == q3py_vmMain) {
-		fprintf(stderr, "vmMain Python method has not been set\n");
+		q3py_error("vmMain Python method has not been set");
 		q3py_exit();
 	}
 }
@@ -167,13 +177,13 @@ Q3_API intptr_t vmMain(int command, int arg0, int arg1, int arg2,
 			if (PyErr_Occurred()) {
 				PyErr_Print();
 			}
-			fprintf(stderr, "vmMain result is not a long\n");
+			q3py_error("vmMain result is not a long");
 			Py_XDECREF(result);
 		}
 	}
 	else {
 		PyErr_Print();
-		fprintf(stderr, "Failed building value for vmMain call\n");
+		q3py_error("Failed building value for vmMain call");
 	}
 
 	q3py_exit();
@@ -189,7 +199,7 @@ Q3_API intptr_t vmMain(int command, int arg0, int arg1, int arg2,
 static void init_python() {
 	const int inittab = PyImport_AppendInittab(Q3PY_MODULE_NAME, &PyInit_q3py);
 	if (-1 == inittab) {
-		fprintf(stderr, "Could not append Python module '%s'\n", Q3PY_MODULE_NAME);
+		q3py_error("Could not append Python module '" Q3PY_MODULE_NAME "'");
 		q3py_exit();
 	}
 
@@ -213,6 +223,9 @@ static void init_python() {
 	PyObject *module = PyImport_Import(moduleName);
 	Py_DECREF(moduleName);
 
+	/* Buffer for formatted error messages, size chosen arbitrarily */
+	char error_message_buffer[128];
+
 	if (module != NULL) {
 		PyObject *function = PyObject_GetAttrString(module, funcname);
 		if (function && PyCallable_Check(function)) {
@@ -225,15 +238,20 @@ static void init_python() {
 				Py_DECREF(module);
 
 				PyErr_Print();
-				fprintf(stderr, "Calling init function '%s' failed\n", funcname);
+				snprintf(error_message_buffer, sizeof(error_message_buffer),
+						"Calling init method '%s' failed", funcname);
+				q3py_error(error_message_buffer);
 				q3py_exit();
 			}
 		}
 		else {
 			if (PyErr_Occurred()) {
 				PyErr_Print();
 			}
-			fprintf(stderr, "Cannot find function '%s'\n", funcname);
+			snprintf(error_message_buffer, sizeof(error_message_buffer),
+					"Can not find method '%s' in module '%s'",
+					funcname, modname);
+			q3py_error(error_message_buffer);
 			q3py_exit();
 		}
 
@@ -242,19 +260,25 @@ static void init_python() {
 	}
 	else {
 		PyErr_Print();
-		fprintf(stderr, "Failed to load module '%s'\n", modname);
+		snprintf(error_message_buffer, sizeof(error_message_buffer),
+				"Failed to load module '%s'", modname);
+		q3py_error(error_message_buffer);
 		q3py_exit();
 	}
 }
 
 Q3_API void dllEntry(const syscallptr * const syscallptr) {
 	/* A NULL pointer is the only invalid value we can check for */
 	if (NULL == syscallptr) {
-		fprintf(stderr, "NULL syscall pointer\n");
+		q3py_error("NULL syscall pointer");
 		q3py_exit();
 	}
 
 	q3_syscall = syscallptr;
+	char message_buffer[128];
+	snprintf(message_buffer, sizeof(message_buffer),
+			"dllEntry called with syscall %p", syscallptr);
+	q3py_log(message_buffer);
 
 	init_python();
 	/* TODO: Split initialization of Python and dllEntry? */