Introduce Gattlib logging backend

CMakeLists.txt

@@ -58,6 +58,11 @@ else()
   set(GATTLIB_DBUS TRUE)
 endif()
 
+# With 'syslog' backend, we enable all logs (ie: up to level debug) and we leave the
+# application to set the level using 'setlogmask()'
+set(GATTLIB_LOG_LEVEL 3 CACHE STRING "Define the minimum logging level for Gattlib (0=error, 1=warning, 2=info, 3=debug)")
+set(GATTLIB_LOG_BACKEND syslog CACHE STRING "Define logging backend: syslog, printf (default: syslog)")
+
 if (GATTLIB_DBUS)
   # Build dbus-based gattlib
   add_subdirectory(dbus)

bluez/CMakeLists.txt

@@ -77,7 +77,8 @@ set(gattlib_SRCS gattlib_adapter.c
                  gattlib_discover.c
                  gattlib_read_write.c
                  ${CMAKE_SOURCE_DIR}/common/gattlib_common.c
-                 ${CMAKE_SOURCE_DIR}/common/gattlib_eddystone.c)
+                 ${CMAKE_SOURCE_DIR}/common/gattlib_eddystone.c
+                 ${CMAKE_SOURCE_DIR}/common/logging_backend/${GATTLIB_LOG_BACKEND}/gattlib_logging.c)
 
 # Added Glib support
 pkg_search_module(GLIB REQUIRED glib-2.0)
@@ -99,6 +100,11 @@ else()
 endif()
 
 # gattlib
+target_compile_definitions(gattlib PUBLIC -DGATTLIB_LOG_LEVEL=${GATTLIB_LOG_LEVEL})
+if (GATTLIB_LOG_BACKEND STREQUAL "syslog")
+	target_compile_definitions(gattlib PUBLIC -DGATTLIB_LOG_BACKEND_SYSLOG)
+endif()
+
 include(GNUInstallDirs)
 if(GATTLIB_SHARED_LIB)
   add_library(gattlib SHARED ${gattlib_SRCS})

bluez/gattlib_discover.c

@@ -84,7 +84,7 @@ int gattlib_discover_primary(gatt_connection_t* connection, gattlib_primary_serv
 	gattlib_context_t* conn_context = connection->context;
 	ret = gatt_discover_primary(conn_context->attrib, NULL, primary_all_cb, &user_data);
 	if (ret == 0) {
-		fprintf(stderr, "Fail to discover primary services.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Fail to discover primary services.");
 		return GATTLIB_ERROR_BLUEZ;
 	}
 
@@ -156,7 +156,7 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 	gattlib_context_t* conn_context = connection->context;
 	ret = gatt_discover_char(conn_context->attrib, start, end, NULL, characteristic_cb, &user_data);
 	if (ret == 0) {
-		fprintf(stderr, "Fail to discover characteristics.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Fail to discover characteristics.");
 		return GATTLIB_ERROR_BLUEZ;
 	}
 

common/gattlib_common.c

@@ -80,7 +80,7 @@ void gattlib_call_notification_handler(struct gattlib_handler *handler, const uu
 	}
 #endif
 	else {
-		fprintf(stderr, "Invalid notification handler.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Invalid notification handler.");
 	}
 }
 
@@ -100,7 +100,7 @@ void gattlib_call_disconnection_handler(struct gattlib_handler *handler) {
 	}
 #endif
 	else {
-		fprintf(stderr, "Invalid disconnection handler.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Invalid disconnection handler.");
 	}
 }
 

common/gattlib_eddystone.c

@@ -57,7 +57,7 @@ int gattlib_adapter_scan_eddystone(void *adapter, int16_t rssi_threshold, uint32
 
 	ret = gattlib_string_to_uuid(EDDYSTONE_SERVICE_UUID, strlen(EDDYSTONE_SERVICE_UUID) + 1, &eddystone_uuid);
 	if (ret != 0) {
-		fprintf(stderr, "Fail to convert characteristic TX to UUID.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Fail to convert characteristic TX to UUID.");
 		return GATTLIB_ERROR_INTERNAL;
 	}
 

common/logging_backend/printf/gattlib_logging.c

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-or-later
+ *
+ * Copyright (c) 2021, Olivier Martin <[email protected]>
+ */
+
+#include "gattlib_internal.h"
+
+void gattlib_log(int level, const char *format, ...) {
+	va_list args;
+	FILE *stream = stdout;
+
+	if (level == GATTLIB_ERROR) {
+		stream = stderr;
+	}
+
+	va_start(args, format);
+	vfprintf(stream, format, args);
+	fprintf(stream, "\n");
+	va_end(args);
+}

common/logging_backend/syslog/gattlib_logging.c

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-or-later
+ *
+ * Copyright (c) 2021, Olivier Martin <[email protected]>
+ */
+
+#include <syslog.h>
+
+#include "gattlib_internal.h"
+
+static const int m_gattlib_log_level_to_syslog[] = {
+	LOG_ERR, LOG_WARNING, LOG_INFO, LOG_DEBUG
+};
+
+void gattlib_log(int level, const char *format, ...) {
+	va_list args;
+
+	va_start(args, format);
+	vsyslog(m_gattlib_log_level_to_syslog[level], format, args);
+	va_end(args);
+}

dbus/CMakeLists.txt

@@ -74,6 +74,7 @@ set(gattlib_SRCS gattlib.c
                  bluez5/lib/uuid.c
                  ${CMAKE_CURRENT_LIST_DIR}/../common/gattlib_common.c
                  ${CMAKE_CURRENT_LIST_DIR}/../common/gattlib_eddystone.c
+                 ${CMAKE_CURRENT_LIST_DIR}/../common/logging_backend/${GATTLIB_LOG_BACKEND}/gattlib_logging.c
                  ${CMAKE_CURRENT_BINARY_DIR}/org-bluez-adaptater1.c
                  ${CMAKE_CURRENT_BINARY_DIR}/org-bluez-device1.c
                  ${CMAKE_CURRENT_BINARY_DIR}/org-bluez-gattcharacteristic1.c
@@ -111,6 +112,11 @@ else()
   add_library(gattlib ${gattlib_SRCS})
 endif()
 
+target_compile_definitions(gattlib PUBLIC -DGATTLIB_LOG_LEVEL=${GATTLIB_LOG_LEVEL})
+if (GATTLIB_LOG_BACKEND STREQUAL "syslog")
+	target_compile_definitions(gattlib PUBLIC -DGATTLIB_LOG_BACKEND_SYSLOG)
+endif()
+
 target_include_directories(gattlib PUBLIC ../include)
 target_link_libraries(gattlib ${gattlib_LIBS})
 

dbus/gattlib.c

@@ -38,6 +38,7 @@ gboolean on_handle_device_property_change(
 
 		g_variant_get (arg_changed_properties, "a{sv}", &iter);
 		while (g_variant_iter_loop (iter, "{&sv}", &key, &value)) {
+			GATTLIB_LOG(GATTLIB_DEBUG, "DBUS: device_property_change: %s: %s", key, g_variant_print(value, TRUE));
 			if (strcmp(key, "Connected") == 0) {
 				if (!g_variant_get_boolean(value)) {
 					// Disconnection case
@@ -154,7 +155,7 @@ gatt_connection_t *gattlib_connect(void* adapter, const char *dst, unsigned long
 			&error);
 	if (device == NULL) {
 		if (error) {
-			fprintf(stderr, "Failed to connect to DBus Bluez Device: %s\n", error->message);
+			GATTLIB_LOG(GATTLIB_ERROR, "Failed to connect to DBus Bluez Device: %s", error->message);
 			g_error_free(error);
 		}
 		goto FREE_CONNECTION;
@@ -175,9 +176,9 @@ gatt_connection_t *gattlib_connect(void* adapter, const char *dst, unsigned long
 		if (strncmp(error->message, m_dbus_error_unknown_object, strlen(m_dbus_error_unknown_object)) == 0) {
 			// You might have this error if the computer has not scanned or has not already had
 			// pairing information about the targetted device.
-			fprintf(stderr, "Device '%s' cannot be found\n", dst);
+			GATTLIB_LOG(GATTLIB_ERROR, "Device '%s' cannot be found", dst);
 		}  else {
-			fprintf(stderr, "Device connected error (device:%s): %s\n",
+			GATTLIB_LOG(GATTLIB_ERROR, "Device connected error (device:%s): %s",
 				conn_context->device_object_path,
 				error->message);
 		}
@@ -239,7 +240,7 @@ int gattlib_disconnect(gatt_connection_t* connection) {
 
 	org_bluez_device1_call_disconnect_sync(conn_context->device, NULL, &error);
 	if (error) {
-		fprintf(stderr, "Failed to disconnect DBus Bluez Device: %s\n", error->message);
+		GATTLIB_LOG(GATTLIB_ERROR, "Failed to disconnect DBus Bluez Device: %s", error->message);
 		g_error_free(error);
 	}
 
@@ -301,10 +302,10 @@ int gattlib_discover_primary(gatt_connection_t* connection, gattlib_primary_serv
 				&error);
 		if (service_proxy == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open service '%s': %s\n", *service_str, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s': %s", *service_str, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open service '%s'.\n", *service_str);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s'.", *service_str);
 			}
 			continue;
 		}
@@ -343,7 +344,7 @@ int gattlib_discover_primary(gatt_connection_t* connection, gattlib_primary_serv
 	const gchar* const* service_strs = org_bluez_device1_get_uuids(device);
 
 	if (device_manager == NULL) {
-		fprintf(stderr, "Gattlib context not initialized.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Gattlib context not initialized.");
 		return GATTLIB_INVALID_PARAMETER;
 	}
 
@@ -390,10 +391,10 @@ int gattlib_discover_primary(gatt_connection_t* connection, gattlib_primary_serv
 				&error);
 		if (service_proxy == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open service '%s': %s\n", object_path, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s': %s", object_path, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open service '%s'.\n", object_path);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s'.", object_path);
 			}
 			continue;
 		}
@@ -492,10 +493,10 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 				&error);
 		if (service_proxy == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open services '%s': %s\n", *service_str, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open services '%s': %s", *service_str, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open services '%s'.\n", *service_str);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open services '%s'.", *service_str);
 			}
 			continue;
 		}
@@ -539,10 +540,10 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 				&error);
 		if (service_proxy == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open service '%s': %s\n", *service_str, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s': %s", *service_str, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open service '%s'.\n", *service_str);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s'.", *service_str);
 			}
 			continue;
 		}
@@ -572,10 +573,10 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 					&error);
 			if (characteristic_proxy == NULL) {
 				if (error) {
-					fprintf(stderr, "Failed to open characteristic '%s': %s\n", characteristic_str, error->message);
+					GATTLIB_LOG(GATTLIB_ERROR, "Failed to open characteristic '%s': %s", characteristic_str, error->message);
 					g_error_free(error);
 				} else {
-					fprintf(stderr, "Failed to open characteristic '%s'.\n", characteristic_str);
+					GATTLIB_LOG(GATTLIB_ERROR, "Failed to open characteristic '%s'.", characteristic_str);
 				}
 				continue;
 			} else {
@@ -642,10 +643,10 @@ static void add_characteristics_from_service(gattlib_context_t* conn_context, GD
 				&error);
 		if (characteristic == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open characteristic '%s': %s\n", object_path, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open characteristic '%s': %s", object_path, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open characteristic '%s'.\n", object_path);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open characteristic '%s'.", object_path);
 			}
 			continue;
 		}
@@ -704,7 +705,7 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 	GList *l;
 
 	if (device_manager == NULL) {
-		fprintf(stderr, "Gattlib context not initialized.\n");
+		GATTLIB_LOG(GATTLIB_ERROR, "Gattlib context not initialized.");
 		return GATTLIB_INVALID_PARAMETER;
 	}
 
@@ -750,10 +751,10 @@ int gattlib_discover_char_range(gatt_connection_t* connection, int start, int en
 				&error);
 		if (service_proxy == NULL) {
 			if (error) {
-				fprintf(stderr, "Failed to open service '%s': %s\n", object_path, error->message);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s': %s", object_path, error->message);
 				g_error_free(error);
 			} else {
-				fprintf(stderr, "Failed to open service '%s'.\n", object_path);
+				GATTLIB_LOG(GATTLIB_ERROR, "Failed to open service '%s'.", object_path);
 			}
 			continue;
 		}
@@ -808,7 +809,7 @@ int get_bluez_device_from_mac(struct gattlib_adapter *adapter, const char *mac_a
 			NULL,
 			&error);
 	if (error) {
-		fprintf(stderr, "Failed to connection to new DBus Bluez Device: %s\n", error->message);
+		GATTLIB_LOG(GATTLIB_ERROR, "Failed to connection to new DBus Bluez Device: %s", error->message);
 		g_error_free(error);
 		return GATTLIB_ERROR_DBUS;
 	}

dbus/gattlib_adapter.c

@@ -30,10 +30,10 @@ int gattlib_adapter_open(const char* adapter_name, void** adapter) {
 			NULL, &error);
 	if (adapter_proxy == NULL) {
 		if (error) {
-			fprintf(stderr, "Failed to get adapter %s: %s\n", object_path, error->message);
+			GATTLIB_LOG(GATTLIB_ERROR, "Failed to get adapter %s: %s", object_path, error->message);
 			g_error_free(error);
 		} else {
-			fprintf(stderr, "Failed to get adapter %s\n", object_path);
+			GATTLIB_LOG(GATTLIB_ERROR, "Failed to get adapter %s", object_path);
 		}
 		return GATTLIB_ERROR_DBUS;
 	}
@@ -87,10 +87,10 @@ GDBusObjectManager *get_device_manager_from_adapter(struct gattlib_adapter *gatt
 			&error);
 	if (gattlib_adapter->device_manager == NULL) {
 		if (error) {
-			fprintf(stderr, "Failed to get Bluez Device Manager: %s\n", error->message);
+			GATTLIB_LOG(GATTLIB_ERROR, "Failed to get Bluez Device Manager: %s", error->message);
 			g_error_free(error);
 		} else {
-			fprintf(stderr, "Failed to get Bluez Device Manager.\n");
+			GATTLIB_LOG(GATTLIB_ERROR, "Failed to get Bluez Device Manager.");
 		}
 		return NULL;
 	}
@@ -120,7 +120,7 @@ static void device_manager_on_device1_signal(const char* device1_path, struct di
 			NULL,
 			&error);
 	if (error) {
-		fprintf(stderr, "Failed to connection to new DBus Bluez Device: %s\n",
+		GATTLIB_LOG(GATTLIB_ERROR, "Failed to connection to new DBus Bluez Device: %s",
 			error->message);
 		g_error_free(error);
 	}
@@ -159,11 +159,15 @@ static void on_dbus_object_added(GDBusObjectManager *device_manager,
                      gpointer            user_data)
 {
 	const char* object_path = g_dbus_object_get_object_path(G_DBUS_OBJECT(object));
+
 	GDBusInterface *interface = g_dbus_object_manager_get_interface(device_manager, object_path, "org.bluez.Device1");
 	if (!interface) {
+		GATTLIB_LOG(GATTLIB_DEBUG, "DBUS: on_object_added: %s (not 'org.bluez.Device1')", object_path);
 		return;
 	}
 
+	GATTLIB_LOG(GATTLIB_DEBUG, "DBUS: on_object_added: %s (has 'org.bluez.Device1')", object_path);
+
 	// It is a 'org.bluez.Device1'
 	device_manager_on_device1_signal(object_path, user_data);
 
@@ -178,6 +182,11 @@ on_interface_proxy_properties_changed (GDBusObjectManagerClient *device_manager,
                                        const gchar *const       *invalidated_properties,
                                        gpointer                  user_data)
 {
+	GATTLIB_LOG(GATTLIB_DEBUG, "DBUS: on_interface_proxy_properties_changed: interface:%s changed_properties:%s invalidated_properties:%s",
+			g_dbus_proxy_get_interface_name(interface_proxy),
+			g_variant_print(changed_properties, TRUE),
+			invalidated_properties);
+
 	// Check if the object is a 'org.bluez.Device1'
 	if (strcmp(g_dbus_proxy_get_interface_name(interface_proxy), "org.bluez.Device1") != 0) {
 		return;
@@ -228,8 +237,8 @@ int gattlib_adapter_scan_enable_with_filter(void *adapter, uuid_t **uuid_list, i
 	}
 
 	if (error) {
-		printf("error: %d.%d\n", error->domain, error->code);
-		fprintf(stderr, "Failed to set discovery filter: %s\n", error->message);
+		GATTLIB_LOG(GATTLIB_ERROR, "Failed to set discovery filter: %s (%d.%d)",
+				error->message, error->domain, error->code);
 		g_error_free(error);
 		return GATTLIB_ERROR_DBUS;
 	}
@@ -267,7 +276,7 @@ int gattlib_adapter_scan_enable_with_filter(void *adapter, uuid_t **uuid_list, i
 	// Now, start BLE discovery
 	org_bluez_adapter1_call_start_discovery_sync(gattlib_adapter->adapter_proxy, NULL, &error);
 	if (error) {
-		fprintf(stderr, "Failed to start discovery: %s\n", error->message);
+		GATTLIB_LOG(GATTLIB_ERROR, "Failed to start discovery: %s", error->message);
 		g_error_free(error);
 		return GATTLIB_ERROR_DBUS;
 	}

dbus/gattlib_advertisement.c

@@ -40,8 +40,8 @@ int get_advertisement_data_from_device(OrgBluezDevice1 *bluez_device1,
 	manufacturer_data_variant = org_bluez_device1_get_manufacturer_data(bluez_device1);
 	if (manufacturer_data_variant != NULL) {
 		if (g_variant_n_children(manufacturer_data_variant) != 1) {
-			fprintf(stderr, "Warning: Manufacturer Data with multiple children: %s\n",
-				g_variant_print(manufacturer_data_variant, TRUE));
+			GATTLIB_LOG(GATTLIB_WARNING, "Manufacturer Data with multiple children: %s",
+					g_variant_print(manufacturer_data_variant, TRUE));
 			return GATTLIB_NOT_SUPPORTED;
 		}
 		GVariant* manufacturer_data_dict = g_variant_get_child_value(manufacturer_data_variant, 0);