third_party/libusb/open-fd.patch

diff --git a/third_party/libusb/src/libusb/core.c b/third_party/libusb/src/libusb/core.c
index e816284..abc4f89 100644
--- a/third_party/libusb/src/libusb/core.c
+++ b/third_party/libusb/src/libusb/core.c
@@ -1129,6 +1129,83 @@ int API_EXPORTED libusb_open(libusb_device *dev,
 }
 
 /** \ingroup dev
+ * Open a device and obtain a device handle. A handle allows you to perform
+ * I/O on the device in question.
+ *
+ * Instead of opening the device itself this function accepts an open file
+ * descriptor that it will take ownership of.
+ *
+ * Internally, this function adds a reference to the device and makes it
+ * available to you through libusb_get_device(). This reference is removed
+ * during libusb_close().
+ *
+ * This is a non-blocking function; no requests are sent over the bus.
+ *
+ * \param dev the device to open
+ * \param fd open file handle to the device
+ * \param handle output location for the returned device handle pointer. Only
+ * populated when the return code is 0.
+ * \returns 0 on success
+ * \returns LIBUSB_ERROR_NO_MEM on memory allocation failure
+ * \returns LIBUSB_ERROR_ACCESS if the user has insufficient permissions
+ * \returns LIBUSB_ERROR_NO_DEVICE if the device has been disconnected
+ * \returns another LIBUSB_ERROR code on other failure
+ */
+int API_EXPORTED libusb_open_fd(libusb_device *dev,
+  int fd,
+  libusb_device_handle **handle)
+{
+  struct libusb_context *ctx = DEVICE_CTX(dev);
+  struct libusb_device_handle *_handle;
+  size_t priv_size = usbi_backend->device_handle_priv_size;
+  int r;
+  usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);
+
+  if (!dev->attached) {
+    return LIBUSB_ERROR_NO_DEVICE;
+  }
+
+  _handle = malloc(sizeof(*_handle) + priv_size);
+  if (!_handle)
+    return LIBUSB_ERROR_NO_MEM;
+
+  r = usbi_mutex_init(&_handle->lock, NULL);
+  if (r) {
+    free(_handle);
+    return LIBUSB_ERROR_OTHER;
+  }
+
+  _handle->dev = libusb_ref_device(dev);
+  _handle->auto_detach_kernel_driver = 0;
+  _handle->claimed_interfaces = 0;
+  memset(&_handle->os_priv, 0, priv_size);
+
+  r = usbi_backend->open_fd(_handle, fd);
+  if (r < 0) {
+    usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
+    libusb_unref_device(dev);
+    usbi_mutex_destroy(&_handle->lock);
+    free(_handle);
+    return r;
+  }
+
+  usbi_mutex_lock(&ctx->open_devs_lock);
+  list_add(&_handle->list, &ctx->open_devs);
+  usbi_mutex_unlock(&ctx->open_devs_lock);
+  *handle = _handle;
+
+  /* At this point, we want to interrupt any existing event handlers so
+   * that they realise the addition of the new device's poll fd. One
+   * example when this is desirable is if the user is running a separate
+   * dedicated libusbx events handling thread, which is running with a long
+   * or infinite timeout. We want to interrupt that iteration of the loop,
+   * so that it picks up the new fd, and then continues. */
+  usbi_fd_notification(ctx);
+
+  return 0;
+}
+
+/** \ingroup dev
  * Convenience function for finding a device with a particular
  * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
  * for those scenarios where you are using libusbx to knock up a quick test
diff --git a/third_party/libusb/src/libusb/libusb.h b/third_party/libusb/src/libusb/libusb.h
index d144b3e..5d60951 100644
--- a/third_party/libusb/src/libusb/libusb.h
+++ b/third_party/libusb/src/libusb/libusb.h
@@ -1371,6 +1371,8 @@ int LIBUSB_CALL libusb_get_max_iso_packet_size(libusb_device *dev,
 	unsigned char endpoint);
 
 int LIBUSB_CALL libusb_open(libusb_device *dev, libusb_device_handle **handle);
+int LIBUSB_CALL libusb_open_fd(libusb_device *dev, int fd,
+	libusb_device_handle **handle);
 void LIBUSB_CALL libusb_close(libusb_device_handle *dev_handle);
 libusb_device * LIBUSB_CALL libusb_get_device(libusb_device_handle *dev_handle);
 
diff --git a/third_party/libusb/src/libusb/libusbi.h b/third_party/libusb/src/libusb/libusbi.h
index bc608b92..eb2f0e6 100644
--- a/third_party/libusb/src/libusb/libusbi.h
+++ b/third_party/libusb/src/libusb/libusbi.h
@@ -615,6 +615,11 @@ struct usbi_os_backend {
 	 */
 	int (*open)(struct libusb_device_handle *handle);
 
+	/* Like open() above but uses the file descriptor provided instead of opening
+	 * one on its own.
+	 */
+	int (*open_fd)(struct libusb_device_handle *handle, int fd);
+
 	/* Close a device such that the handle cannot be used again. Your backend
 	 * should destroy any resources that were allocated in the open path.
 	 * This may also be a good place to call usbi_remove_pollfd() to inform
diff --git a/third_party/libusb/src/libusb/os/darwin_usb.c b/third_party/libusb/src/libusb/os/darwin_usb.c
index f95706a..f6b397e 100644
--- a/third_party/libusb/src/libusb/os/darwin_usb.c
+++ b/third_party/libusb/src/libusb/os/darwin_usb.c
@@ -1877,6 +1877,7 @@ const struct usbi_os_backend darwin_backend = {
         .get_config_descriptor = darwin_get_config_descriptor,
 
         .open = darwin_open,
+        .open_fd = NULL, /* not implemented */
         .close = darwin_close,
         .get_configuration = darwin_get_configuration,
         .set_configuration = darwin_set_configuration,
diff --git a/third_party/libusb/src/libusb/os/linux_usbfs.c b/third_party/libusb/src/libusb/os/linux_usbfs.c
index 142fa2b..e965856 100644
--- a/third_party/libusb/src/libusb/os/linux_usbfs.c
+++ b/third_party/libusb/src/libusb/os/linux_usbfs.c
@@ -1259,26 +1259,12 @@ static int linux_default_scan_devices (struct libusb_context *ctx)
 }
 #endif
 
-static int op_open(struct libusb_device_handle *handle)
+static int op_open_fd(struct libusb_device_handle *handle, int fd)
 {
 	struct linux_device_handle_priv *hpriv = _device_handle_priv(handle);
 	int r;
 
-	hpriv->fd = _get_usbfs_fd(handle->dev, O_RDWR, 0);
-	if (hpriv->fd < 0) {
-		if (hpriv->fd == LIBUSB_ERROR_NO_DEVICE) {
-			/* device will still be marked as attached if hotplug monitor thread
-			 * hasn't processed remove event yet */
-			usbi_mutex_static_lock(&linux_hotplug_lock);
-			if (handle->dev->attached) {
-				usbi_dbg("open failed with no device, but device still attached");
-				linux_device_disconnected(handle->dev->bus_number,
-						handle->dev->device_address, NULL);
-			}
-			usbi_mutex_static_unlock(&linux_hotplug_lock);
-		}
-		return hpriv->fd;
-	}
+	hpriv->fd = fd;
 
 	r = ioctl(hpriv->fd, IOCTL_USBFS_GET_CAPABILITIES, &hpriv->caps);
 	if (r < 0) {
@@ -1296,6 +1282,29 @@ static int op_open(struct libusb_device_handle *handle)
 	return usbi_add_pollfd(HANDLE_CTX(handle), hpriv->fd, POLLOUT);
 }
 
+static int op_open(struct libusb_device_handle *handle)
+{
+	struct linux_device_handle_priv *hpriv = _device_handle_priv(handle);
+	int fd = _get_usbfs_fd(handle->dev, O_RDWR, 0);
+
+	if (fd < 0) {
+		if (fd == LIBUSB_ERROR_NO_DEVICE) {
+			/* device will still be marked as attached if hotplug monitor thread
+			 * hasn't processed remove event yet */
+			usbi_mutex_static_lock(&linux_hotplug_lock);
+			if (handle->dev->attached) {
+				usbi_dbg("open failed with no device, but device still attached");
+				linux_device_disconnected(handle->dev->bus_number,
+						handle->dev->device_address, NULL);
+			}
+			usbi_mutex_static_unlock(&linux_hotplug_lock);
+		}
+		return fd;
+	}
+
+	return op_open_fd(handle, fd);
+}
+
 static void op_close(struct libusb_device_handle *dev_handle)
 {
 	int fd = _device_handle_priv(dev_handle)->fd;
@@ -2570,6 +2579,7 @@ const struct usbi_os_backend linux_usbfs_backend = {
 	.get_config_descriptor_by_value = op_get_config_descriptor_by_value,
 
 	.open = op_open,
+	.open_fd = op_open_fd,
 	.close = op_close,
 	.get_configuration = op_get_configuration,
 	.set_configuration = op_set_configuration,
diff --git a/third_party/libusb/src/libusb/os/openbsd_usb.c b/third_party/libusb/src/libusb/os/openbsd_usb.c
index 2997e53..2d24f2c 100644
--- a/third_party/libusb/src/libusb/os/openbsd_usb.c
+++ b/third_party/libusb/src/libusb/os/openbsd_usb.c
@@ -98,6 +98,7 @@ const struct usbi_os_backend openbsd_backend = {
 	obsd_get_device_list,
 	NULL,				/* hotplug_poll */
 	obsd_open,
+	NULL,       /* open_fd */
 	obsd_close,
 
 	obsd_get_device_descriptor,
diff --git a/third_party/libusb/src/libusb/os/wince_usb.c b/third_party/libusb/src/libusb/os/wince_usb.c
index 90c129b..c069c56 100644
--- a/third_party/libusb/src/libusb/os/wince_usb.c
+++ b/third_party/libusb/src/libusb/os/wince_usb.c
@@ -990,6 +990,7 @@ const struct usbi_os_backend wince_backend = {
         wince_get_device_list,
 	NULL,				/* hotplug_poll */
         wince_open,
+        NULL, /* open_fd */
         wince_close,
 
         wince_get_device_descriptor,
diff --git a/third_party/libusb/src/libusb/os/windows_usb.c b/third_party/libusb/src/libusb/os/windows_usb.c
index 4469992..bc4def6 100644
--- a/third_party/libusb/src/libusb/os/windows_usb.c
+++ b/third_party/libusb/src/libusb/os/windows_usb.c
@@ -2290,6 +2290,7 @@ const struct usbi_os_backend windows_backend = {
 	windows_get_device_list,
 	NULL,				/* hotplug_poll */
 	windows_open,
+	NULL,       /* open_fd */
 	windows_close,
 
 	windows_get_device_descriptor,