Currently applications for devices which only are accessed from userspace
can use claim / release interface to make sure they don't get in each others
way. The same however does not work for applications which first need to detach
a "native" / in kernel driver, as this detach will not only detach native
drivers but also the usbfs driver, thus stealing the device from another
userspace / libusbx app.
This patch fixes libusb_detach_kernel_driver to only detach "real" kernel
drivers and not the special usbfs driver used for userspace access to
USB devices. If the usbfs driver is found LIBUSB_ERROR_NOT_FOUND will be
returned to indicate no driver was detached.
Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
libusb/core.c | 4 ++++
libusb/os/linux_usbfs.c | 6 ++++++
2 files changed, 10 insertions(+)
diff --git a/libusb/core.c b/libusb/core.c
index 7c2f4d7..4c513f7 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -1513,6 +1513,10 @@ int API_EXPORTED
libusb_kernel_driver_active(libusb_device_handle *dev,
*
* This functionality is not available on Darwin or Windows.
*
+ * Note that libusb itself also talks to the device through a special kernel
+ * driver, if this driver is already attached to the device, this call will
+ * not detach it and return LIBUSB_ERROR_NOT_FOUND.
+ *
* \param dev a device handle
* \param interface_number the interface to detach the driver from
* \returns 0 on success
diff --git a/libusb/os/linux_usbfs.c b/libusb/os/linux_usbfs.c
index 839ebde..1407866 100644
--- a/libusb/os/linux_usbfs.c
+++ b/libusb/os/linux_usbfs.c
@@ -1538,12 +1538,18 @@ static int op_detach_kernel_driver(struct
libusb_device_handle *handle,
{
int fd = _device_handle_priv(handle)->fd;
struct usbfs_ioctl command;
+ struct usbfs_getdriver getdrv;
int r;
command.ifno = interface;
command.ioctl_code = IOCTL_USBFS_DISCONNECT;
command.data = NULL;
+ getdrv.interface = interface;
+ r = ioctl(fd, IOCTL_USBFS_GETDRIVER, &getdrv);
+ if (r == 0 && strcmp(getdrv.driver, "usbfs") == 0)
+ return LIBUSB_ERROR_NOT_FOUND;
+
r = ioctl(fd, IOCTL_USBFS_IOCTL, &command);
if (r) {
if (errno == ENODATA)
--
1.7.11.4
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