scan: Fix default backends list containing disabled backends

Use CMake to give us a list of the backends available for scanning. This
makes sure that the context scan won't fail by trying to scan from a
backend that wasn't enabled.

Fixes #794.

Signed-off-by: Paul Cercueil <[email protected]>

Author: pcercuei

CMakeLists.txt

@@ -150,6 +150,7 @@ if (WITH_USB_BACKEND)
 		message(SEND_ERROR "Unable to find libusb-1.0 dependency.\n"
 			"If you want to disable the USB backend, set WITH_USB_BACKEND=OFF.")
 	else()
+		list(APPEND LIBIIO_SCAN_BACKENDS usb)
 		set(IIOD_CLIENT 1)
 		set(NEED_LIBXML2 1)
 		set(NEED_THREADS 1)
@@ -250,6 +251,8 @@ if(WITH_LOCAL_BACKEND)
 
 	option(WITH_LOCAL_MMAP_API "Use the mmap API provided in Analog Devices' kernel (not upstream)" ON)
 	option(WITH_HWMON "Add compatibility with the hardware monitoring (hwmon) subsystem" OFF)
+
+	list(APPEND LIBIIO_SCAN_BACKENDS local)
 endif()
 
 option(WITH_SERIAL_BACKEND "Enable the serial backend" OFF)
@@ -358,6 +361,10 @@ if(WITH_NETWORK_BACKEND)
 		list(APPEND LIBS_TO_LINK ${AVAHI_LIBRARIES})
 	endif()
 
+	if (HAVE_DNS_SD)
+		list(APPEND LIBIIO_SCAN_BACKENDS ip)
+	endif()
+
 	set(NEED_THREADS 1)
 	set(IIOD_CLIENT 1)
 	set(NEED_LIBXML2 1)
@@ -612,6 +619,8 @@ if (WITH_USB_BACKEND AND CMAKE_SYSTEM_NAME MATCHES "^Linux")
 	endif()
 endif()
 
+string(REPLACE ";" "," LIBIIO_SCAN_BACKENDS "${LIBIIO_SCAN_BACKENDS}")
+
 configure_file(iio-config.h.cmakein ${CMAKE_CURRENT_BINARY_DIR}/iio-config.h @ONLY)
 
 list(APPEND IIO_FEATURES_${WITH_XML_BACKEND} xml)

iio-config.h.cmakein

@@ -7,6 +7,8 @@
 
 #define LOG_LEVEL @LOG_LEVEL@_L
 
+#define LIBIIO_SCAN_BACKENDS	"@LIBIIO_SCAN_BACKENDS@"
+
 #cmakedefine01 WITH_LOCAL_BACKEND
 #cmakedefine01 WITH_XML_BACKEND
 #cmakedefine01 WITH_NETWORK_BACKEND

scan.c

@@ -155,7 +155,7 @@ struct iio_scan_context * iio_create_scan_context(
 		return NULL;
 	}
 
-	ctx->backendopts = iio_strndup(backend ? backend : "local,usb,ip", PATH_MAX);
+	ctx->backendopts = iio_strndup(backend ? backend : LIBIIO_SCAN_BACKENDS, PATH_MAX);
 	if (!ctx->backendopts) {
 		free(ctx);
 		errno = ENOMEM;