Add hotplug support.

The internal API is changing as follows:
 - Adding two new functions. usbi_connect_device, and usbi_disconnect_device.
   Backends must call these functions to add them to the context's device list
   at one of two places: initial enumeration (done at init), and on device
   attach and removal. These functions need to be called once per context.
 - Backends that support hotplug should not provide a get_device_list funtion.
   This function is now deprecated and will likely be removed once all backends
   support hotplug.

The external API is changing as follows:
 - Two new functions have been added to register and deregister callbacks for
   hotplug notification: libusb_hotplug_register_callback(),
   libusb_hotplug_deregister_callback(). Hotplug callbacks are called by
   libusb_handle_events(). Details of the new API can be found in libusb.h.
 - A new capability check has been added to check for hotplug support. See
   LIBUSB_CAP_HAS_HOTPLUG.

Aa suggested by Xiaofan add new example has been added to show how to use
the new external hotplug API. See examples/hotplugtest.c.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>

2 files changed, 97 insertions, 1 deletions

diff --git a/examples/Makefile.am b/examples/Makefile.am
index a28a300..380e13f 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -1,7 +1,7 @@
 AM_CPPFLAGS = -I$(top_srcdir)/libusb
 LDADD = ../libusb/libusb-1.0.la
 
-noinst_PROGRAMS = listdevs xusb fxload
+noinst_PROGRAMS = listdevs xusb fxload hotplugtest
 
 if HAVE_SIGACTION
 noinst_PROGRAMS += dpfp
diff --git a/examples/hotplugtest.c b/examples/hotplugtest.c
new file mode 100644
index 0000000..6f16827
--- /dev/null
+++ b/examples/hotplugtest.c
@@ -0,0 +1,96 @@
+/*
+ * libusb example program for hotplug API
+ * Copyright © 2012-2013 Nathan Hjelm <hjelmn@mac.ccom>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "libusb.h"
+
+int done = 0;
+libusb_device_handle *handle;
+
+static int LIBUSB_CALL hotplug_callback(libusb_context *ctx, libusb_device *dev, libusb_hotplug_event event, void *user_data)
+{
+	struct libusb_device_descriptor desc;
+	int rc;
+
+	rc = libusb_get_device_descriptor(dev, &desc);
+	if (LIBUSB_SUCCESS != rc) {
+		fprintf (stderr, "Error getting device descriptor\n");
+	}
+
+	printf ("Device attached: %04x:%04x\n", desc.idVendor, desc.idProduct);
+
+	libusb_open (dev, &handle);
+
+	done++;
+
+	return 0;
+}
+
+static int LIBUSB_CALL hotplug_callback_detach(libusb_context *ctx, libusb_device *dev, libusb_hotplug_event event, void *user_data)
+{
+	printf ("Device detached\n");
+
+	libusb_close (handle);
+
+	done++;
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	libusb_hotplug_callback_handle hp[2];
+	int product_id, vendor_id, class_id;
+	int rc;
+
+	vendor_id  = (argc > 1) ? strtol (argv[1], NULL, 0) : 0x045a;
+	product_id = (argc > 2) ? strtol (argv[2], NULL, 0) : 0x5005;
+	class_id   = (argc > 3) ? strtol (argv[3], NULL, 0) : LIBUSB_HOTPLUG_MATCH_ANY;
+
+	libusb_init (NULL);
+
+	if (!libusb_has_capability (LIBUSB_CAP_HAS_HOTPLUG)) {
+		printf ("Hotplug capabilites are not supported on this platform\n");
+		libusb_exit (NULL);
+		return EXIT_FAILURE;
+	}
+
+	rc = libusb_hotplug_register_callback (NULL, LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED, 0, vendor_id,
+		product_id, class_id, hotplug_callback, NULL, &hp[0]);
+	if (LIBUSB_SUCCESS != rc) {
+		fprintf (stderr, "Error registering callback 0\n");
+		libusb_exit (NULL);
+		return EXIT_FAILURE;
+	}
+
+	rc = libusb_hotplug_register_callback (NULL, LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT, 0, vendor_id,
+		product_id,class_id, hotplug_callback_detach, NULL, &hp[1]);
+	if (LIBUSB_SUCCESS != rc) {
+		fprintf (stderr, "Error registering callback 1\n");
+		libusb_exit (NULL);
+		return EXIT_FAILURE;
+	}
+
+	while (done < 2) {
+		libusb_handle_events (NULL);
+	}
+
+	libusb_exit (NULL);
+}