dev-libs/libusb/files/libusb-1.0.21-open-fd.patch

From bcda70ea60b19e0226ebd8d2368de17185eb63b2 Mon Sep 17 00:00:00 2001
From: Jingkui Wang <jkwang@google.com>
Date: Tue, 30 Oct 2018 15:29:02 -0700
Subject: [PATCH] add libusb_open_fd

libusb_open_fd will take an external fd to construct device handle. This will
all sandboxing libusb.

This patch is adapted from chromium repo:
    src/third_party/libusb/open-fd.patch
---
 libusb/core.c           | 69 +++++++++++++++++++++++++++++++++++++++++
 libusb/libusb.h         |  2 ++
 libusb/libusbi.h        |  5 +++
 libusb/os/linux_usbfs.c | 62 +++++++++++++++++++++++-------------
 4 files changed, 117 insertions(+), 21 deletions(-)

diff --git a/libusb/core.c b/libusb/core.c
index 99aab7b..8c9b8e9 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -1282,6 +1282,75 @@ int API_EXPORTED libusb_open(libusb_device *dev,
 	return 0;
 }
 
+/** \ingroup libusb_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);
+  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;
+
+  return 0;
+}
+
 /** \ingroup libusb_dev
  * Convenience function for finding a device with a particular
  * <tt>idVendor</tt>/<tt>idProduct</tt> combination. This function is intended
diff --git a/libusb/libusb.h b/libusb/libusb.h
index f73e31c..34d0784 100644
--- a/libusb/libusb.h
+++ b/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 **dev_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/libusb/libusbi.h b/libusb/libusbi.h
index cc0906c..ca5e86a 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -712,6 +712,11 @@ struct usbi_os_backend {
 	 */
 	int (*open)(struct libusb_device_handle *dev_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/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 9cbeb80..89102ef 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -187,6 +187,11 @@ static int _get_usbfs_fd(struct libusb_device *dev, mode_t mode, int silent)
 	int fd;
 	int delay = 10000;
 
+	if (!usbfs_path) {
+		usbi_err(ctx, "could not find usbfs");
+		return LIBUSB_ERROR_OTHER;
+	}
+
 	if (usbdev_names)
 		snprintf(path, PATH_MAX, "%s/usbdev%d.%d",
 			usbfs_path, dev->bus_number, dev->device_address);
@@ -379,10 +384,6 @@ static int op_init(struct libusb_context *ctx)
 	int r;
 
 	usbfs_path = find_usbfs_path();
-	if (!usbfs_path) {
-		usbi_err(ctx, "could not find usbfs");
-		return LIBUSB_ERROR_OTHER;
-	}
 
 	if (monotonic_clkid == -1)
 		monotonic_clkid = find_monotonic_clock();
@@ -1138,6 +1139,11 @@ static int usbfs_scan_busdir(struct libusb_context *ctx, uint8_t busnum)
 	struct dirent *entry;
 	int r = LIBUSB_ERROR_IO;
 
+	if (!usbfs_path) {
+		usbi_err(ctx, "could not find usbfs");
+		return LIBUSB_ERROR_OTHER;
+	}
+
 	snprintf(dirpath, PATH_MAX, "%s/%03d", usbfs_path, busnum);
 	usbi_dbg("%s", dirpath);
 	dir = opendir(dirpath);
@@ -1175,6 +1181,12 @@ static int usbfs_scan_busdir(struct libusb_context *ctx, uint8_t busnum)
 static int usbfs_get_device_list(struct libusb_context *ctx)
 {
 	struct dirent *entry;
+
+	if (!usbfs_path) {
+		usbi_err(ctx, "could not find usbfs");
+		return LIBUSB_ERROR_OTHER;
+	}
+
 	DIR *buses = opendir(usbfs_path);
 	int r = 0;
 
@@ -1280,26 +1292,12 @@ 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);
-			}
-			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) {
@@ -1317,10 +1315,31 @@ static int op_open(struct libusb_device_handle *handle)
 	r = usbi_add_pollfd(HANDLE_CTX(handle), hpriv->fd, POLLOUT);
 	if (r < 0)
 		close(hpriv->fd);
-
 	return r;
 }
 
+static int op_open(struct libusb_device_handle *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);
+			}
+			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)
 {
 	struct linux_device_handle_priv *hpriv = _device_handle_priv(dev_handle);
@@ -2696,6 +2715,7 @@ 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,
-- 
2.20.0.rc0.387.gc7a69e6b6c-goog