Compile code using bluez gatt api

Question

I am currently implementing a BLE server using GATT api from bluez5 in C. I need to use my own service with custom characteristics.

Problem is that bluez5 does not install all header of GATT api. Same problem in libbluetooth with does not provide all external GATTapi.

Am I using the wrong api ? What is the tips to compile my code ? Current dirty solution is to replace btgatt-server.c in tools directory of bluez source by my own code to be able to dev/test my implementation.

EDIT : I am using the last stable version of bluez : 5.32

headers from bluez that I need to compile my code :

#include "lib/bluetooth.h"
#include "lib/hci.h"
#include "lib/hci_lib.h"
#include "lib/l2cap.h"
#include "lib/uuid.h"

#include "src/shared/mainloop.h"
#include "src/shared/util.h"
#include "src/shared/att.h"
#include "src/shared/queue.h"
#include "src/shared/timeout.h"
#include "src/shared/gatt-db.h"
#include "src/shared/gatt-server.h"

functions :

[arthur ] make 2>&1 | grep gatt_ | grep implicit
tools/btgatt-server.c:32:2: error: implicit declaration of function ‘gatt_db_attribute_read_result’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:60:2: error: implicit declaration of function ‘gatt_db_add_service’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:67:2: error: implicit declaration of function ‘gatt_db_service_add_characteristic’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:94:2: error: implicit declaration of function ‘gatt_db_service_set_active’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:110:2: error: implicit declaration of function ‘bt_gatt_server_unref’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:111:2: error: implicit declaration of function ‘gatt_db_unref’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:186:2: error: implicit declaration of function ‘gatt_db_new’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:192:2: error: implicit declaration of function ‘bt_gatt_server_new’ [-Werror=implicit-function-declaration]
tools/btgatt-server.c:202:2: error: implicit declaration of function ‘bt_gatt_server_set_debug’ [-Werror=implicit-function-declaration]

These includes are not install by the Makefile of bluez on my system. And the library file does not include the function that I need either.

Answer 1

I will probably used dbus API later. But right now I am always using low c API from bluez5 (path of example from bluez5 : bluez5_utils-5.31/tools/btgatt-server.c). To compile this standalone code outside bluez5 source directory I am using some include/library from bluez5 :

• libshared-mainloop.a
• libbluetooth-internal.a

In my case I am working with buildroot. So I add some piece of code in bluez5 mk file to get this missing library :

define BLUEZ5_UTILS_EXTERNALIZE_GATT
    mkdir -p $(STAGING_DIR)/usr/local/bluez5/gatt
    cp $(BLUEZ5_UTILS_SRCDIR)/src/uuid-helper.o $(STAGING_DIR)/usr/local/bluez5/gatt/.
    cp $(BLUEZ5_UTILS_SRCDIR)/src/.libs/libshared-mainloop.a $(STAGING_DIR)/usr/local/bluez5/gatt/.
    cp $(BLUEZ5_UTILS_SRCDIR)/lib/.libs/libbluetooth-internal.a $(STAGING_DIR)/usr/local/bluez5/gatt/.

    $(INSTALL) -D -m 0755 $(@D)/tools/btmgmt $(STAGING_DIR)/usr/bin/btmgmt
    $(INSTALL) -D -m 0755 $(@D)/tools/btmgmt $(TARGET_DIR)/usr/bin/btmgmt
endef

Then in my Makefile I just need to link with these libraries + add -I to find missing header file which are in bluez5 source directory :

# find bluez5 header
HEADER += -I$(BLUEZ_PATH)

# link bluez5 libraries
BLUEZ5_LIB = $(STAGING_DIR)/usr/local/bluez5/gatt/libshared-mainloop.a BLUEZ5_LIB += $(STAGING_DIR)/usr/local/bluez5/gatt/libbluetooth-internal.a

Anyway this is probably not the best way to do it but it is working great. Moreover you don't need to do anything if you upgrade your bluez5 version. I find some other solution like fork bluez5 and put some modification in Makefile to build a static library which contain all stuff that I need. But this solution is really painfully and you need to update your work at each new bluez5 release.