Minimal test program for libusb leaks on Windows. Relates to https://github.com/libusb/libusb/pull/64

winleak.c

/* Quick sample to demonstrate Windows device leaks from libusb_get_device_list when reusing instances */
#include <stdio.h>
#include "libusb.h"
#include <assert.h>

/* Set to zero to stop after 100 iterations, for running under drmemory/other */
const int RUN_INFINITE = 0;

static libusb_device **stored = NULL;

static void release_stored_devices(void);

static void store_devices(libusb_device **devs, int cnt)
{
	int i =0;
	if(stored)
		release_stored_devices();
	stored = calloc(cnt+1, sizeof(libusb_device *));
	fprintf(stderr, "storing references to device list...\n");
	for(i = 0; devs[i]; i++) {
		stored[i] = devs[i];
		libusb_ref_device(stored[i]);
	}
	fprintf(stderr, "stored %d device references\n", i);
}

static void release_stored_devices(void)
{
	int i = 0;
	if(!stored)
		return; /* nothing stored */
	fprintf(stderr, "dropping references to previously stored stored device refs...\n");
	for(i = 0; stored[i]; i++)
		libusb_unref_device(stored[i]);
	fprintf(stderr, "dropped %d stored refs\n", i);
	free(stored);
	stored = 0;
}

int main(void)
{
	libusb_device **devs;

	int r;
	ssize_t cnt;

	r = libusb_init(NULL);
	if (r < 0) {
		fprintf(stderr, "libusb_init failed %d\n", r);
		return r;
	}

	libusb_set_debug(NULL, 4);

	/* First, read one list of devices and store referenced
	   pointers to them before freeing the device list itself.
	*/
	cnt = libusb_get_device_list(NULL, &devs);
	assert(cnt >= 0);
	store_devices(devs, cnt);
	libusb_free_device_list(devs, 1);

	/* Now, loop around getting and freeing subsequent device lists */
	int loops = 0;
	while(RUN_INFINITE || loops < 100) {
		cnt = libusb_get_device_list(NULL, &devs);
		assert(cnt >= 0);
		libusb_free_device_list(devs, 1);
		fprintf(stderr, "Completed %d loops\n", ++loops);
	}

	fprintf(stderr, "dropping stored devices before stopping (all devices should be freed)\n");
	release_stored_devices();

	libusb_exit(NULL);
	return 0;
}