Add stub routines for mocking libusb

This is to be used for running automated tests on libx52 and associated
libraries and/or programs

Makefile.am

@@ -1,6 +1,6 @@
 ACLOCAL_AMFLAGS = -I m4
 
-SUBDIRS = libx52 test cli util
+SUBDIRS = libx52 cli util libusbx52 test
 
 # Extra files that need to be in the distribution
 EXTRA_DIST = README.md LICENSE

configure.ac

@@ -30,8 +30,9 @@ AC_SUBST([X52_CORE_LIB], [../libx52/libx52.la])
 AC_CONFIG_FILES([
     Makefile
     libx52/Makefile
-    test/Makefile
+    libusbx52/Makefile
     cli/Makefile
     util/Makefile
+    test/Makefile
 ])
 AC_OUTPUT

libusbx52/Makefile.am

@@ -0,0 +1,8 @@
+ACLOCAL_AMFLAGS = -I m4
+
+# libusb stub library for use by test programs
+check_LTLIBRARIES = libusbx52.la
+
+libusbx52_la_SOURCES = usb_x52_stub.c
+
+EXTRA_DIST = README.md

libusbx52/README.md

@@ -0,0 +1,15 @@
+LibUSB mocker library
+=====================
+
+This folder contains a convenience library to mock the API of libusb. This is
+intended to be used as an LD_PRELOAD library when used by automated tests to
+verify the library without needing actual hardware to verify the tests.
+
+While a manual test using real hardware is valuable, running some automated
+tests in an environment where the hardware is not available is equally valuable,
+especially if the source code is changing frequently.
+
+Note that the API exported by the mocker is limited to the API used by libx52,
+as writing a complete USB simulator stack in software is not an easy job, nor is
+it necessary for the purposes of this project.
+

libusbx52/usb_x52_stub.c

@@ -0,0 +1,71 @@
+/*
+ * LibUSB stub driver for testing the Saitek X52/X52 Pro
+ *
+ * Copyright (C) 2017 Nirenjan Krishnan (nirenjan@nirenjan.org)
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License as
+ *  published by the Free Software Foundation, version 2.
+ *
+ */
+
+#include <libusb-1.0/libusb.h>
+
+
+int libusb_init(libusb_context **ctx)
+{
+    // TODO
+    return 0;
+}
+
+void libusb_exit(libusb_context *ctx)
+{
+    // TODO
+}
+
+void libusb_set_debug(libusb_context *ctx, int level)
+{
+    // TODO
+}
+
+ssize_t libusb_get_device_list(libusb_context *ctx, libusb_device ***list)
+{
+    // TODO
+    return 0;
+}
+
+void libusb_free_device_list(libusb_device **list, int unref_devices)
+{
+    // TODO
+}
+
+int libusb_get_device_descriptor(libusb_device *dev,
+                                 struct libusb_device_descriptor *desc)
+{
+    // TODO
+    return 0;
+}
+
+int libusb_open(libusb_device *dev, libusb_device_handle **handle)
+{
+    // TODO
+    return 0;
+}
+
+void libusb_close(libusb_device_handle *dev_handle)
+{
+    // TODO
+}
+
+int libusb_control_transfer(libusb_device_handle *dev_handle,
+                            uint8_t request_type,
+                            uint8_t bRequest,
+                            uint16_t wValue,
+                            uint16_t wIndex,
+                            unsigned char *data,
+                            uint16_t wLength,
+                            unsigned int timeout)
+{
+    // TODO
+    return 0;
+}