usbip: tools: fix GCC8 warning for strncpy

GCC8 started emitting warning about using strncpy with number of bytes
exactly equal destination size which could lead to non-zero terminated
string being copied. Use "SYSFS_PATH_MAX - 1" & "SYSFS_BUS_ID_SIZE - 1"
as number of bytes to ensure name is always zero-terminated.
Signed-off-by: Changcheng Liu <changcheng.liu@aliyun.com>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20190725132209.GA27590@jerryopenixSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/usb/usbip/libsrc/usbip_common.c

@@ -226,8 +226,10 @@ int read_usb_device(struct udev_device *sdev, struct usbip_usb_device *udev)
 	path = udev_device_get_syspath(sdev);
 	name = udev_device_get_sysname(sdev);
 
-	strncpy(udev->path,  path,  SYSFS_PATH_MAX);
-	strncpy(udev->busid, name, SYSFS_BUS_ID_SIZE);
+	strncpy(udev->path,  path,  SYSFS_PATH_MAX - 1);
+	udev->path[SYSFS_PATH_MAX - 1] = '\0';
+	strncpy(udev->busid, name, SYSFS_BUS_ID_SIZE - 1);
+	udev->busid[SYSFS_BUS_ID_SIZE - 1] = '\0';
 
 	sscanf(name, "%u-%u", &busnum, &devnum);
 	udev->busnum = busnum;

tools/usb/usbip/libsrc/usbip_device_driver.c

@@ -91,7 +91,8 @@ int read_usb_vudc_device(struct udev_device *sdev, struct usbip_usb_device *dev)
 	copy_descr_attr16(dev, &descr, idProduct);
 	copy_descr_attr16(dev, &descr, bcdDevice);
 
-	strncpy(dev->path, path, SYSFS_PATH_MAX);
+	strncpy(dev->path, path, SYSFS_PATH_MAX - 1);
+	dev->path[SYSFS_PATH_MAX - 1] = '\0';
 
 	dev->speed = USB_SPEED_UNKNOWN;
 	speed = udev_device_get_sysattr_value(sdev, "current_speed");
@@ -110,7 +111,8 @@ int read_usb_vudc_device(struct udev_device *sdev, struct usbip_usb_device *dev)
 	dev->busnum = 0;
 
 	name = udev_device_get_sysname(plat);
-	strncpy(dev->busid, name, SYSFS_BUS_ID_SIZE);
+	strncpy(dev->busid, name, SYSFS_BUS_ID_SIZE - 1);
+	dev->busid[SYSFS_BUS_ID_SIZE - 1] = '\0';
 	return 0;
 err:
 	fclose(fd);