+/* we traverse usbfs without knowing how many devices we are going to find.
+ * so we create this discovered_devs model which is similar to a linked-list
+ * which grows when required. it can be freed once discovery has completed,
+ * eliminating the need for a list node in the libusb_device structure
+ * itself. */
+#define DISCOVERED_DEVICES_SIZE_STEP 8
+struct discovered_devs {
+ size_t len;
+ size_t capacity;
+ struct libusb_device *devices[0];
+};
+
+static struct discovered_devs *discovered_devs_alloc(void)
+{
+ struct discovered_devs *ret =
+ malloc(sizeof(*ret) + (sizeof(void *) * DISCOVERED_DEVICES_SIZE_STEP));
+
+ if (ret) {
+ ret->len = 0;
+ ret->capacity = DISCOVERED_DEVICES_SIZE_STEP;
+ }
+ return ret;
+}
+
+/* append a device to the discovered devices collection. may realloc itself,
+ * returning new discdevs. returns NULL on realloc failure. */
+static struct discovered_devs *discovered_devs_append(
+ struct discovered_devs *discdevs, struct libusb_device *dev)
+{
+ size_t len = discdevs->len;
+ size_t capacity;
+
+ /* if there is space, just append the device */
+ if (len < discdevs->capacity) {
+ discdevs->devices[len] = dev;
+ discdevs->len++;
+ return discdevs;
+ }
+
+ /* exceeded capacity, need to grow */
+ usbi_dbg("need to increase capacity");
+ capacity = discdevs->capacity + DISCOVERED_DEVICES_SIZE_STEP;
+ discdevs = realloc(discdevs,
+ sizeof(*discdevs) + (sizeof(void *) * capacity));
+ if (discdevs) {
+ discdevs->capacity = capacity;
+ discdevs->devices[len] = dev;
+ discdevs->len++;
+ }
+
+ return discdevs;
+}
+
+static void discovered_devs_free(struct discovered_devs *discdevs)
+{
+ size_t i;
+
+ for (i = 0; i < discdevs->len; i++)
+ libusb_device_unref(discdevs->devices[i]);
+
+ free(discdevs);
+}
+
+/* open a device file, set up the libusb_device structure for it, and add it to
+ * discdevs. on failure (non-zero return) the pre-existing discdevs should
+ * be destroyed (and devices freed). on success, the new discdevs pointer
+ * should be used it may have been moved. */
+static int scan_device(struct discovered_devs **_discdevs,
+ char *busdir, const char *devnum)