Author: hselasky
Date: Tue Jun 26 16:00:16 2018
New Revision: 335669
URL: https://svnweb.freebsd.org/changeset/base/335669
Log:
Improve the userspace USB string reading function in LibUSB.
Some USB devices does not allow a partial descriptor readout.
Found by: bz @
MFC after: 1 week
Sponsored by: Mellanox Technologies
Modified:
head/lib/libusb/libusb20.c
Modified: head/lib/libusb/libusb20.c
==============================================================================
--- head/lib/libusb/libusb20.c Tue Jun 26 15:00:54 2018 (r335668)
+++ head/lib/libusb/libusb20.c Tue Jun 26 16:00:16 2018 (r335669)
@@ -814,6 +814,7 @@ libusb20_dev_req_string_sync(struct libusb20_device *p
{
struct LIBUSB20_CONTROL_SETUP_DECODED req;
int error;
+ int flags;
/* make sure memory is initialised */
memset(ptr, 0, len);
@@ -840,22 +841,24 @@ libusb20_dev_req_string_sync(struct libusb20_device *p
error = libusb20_dev_request_sync(pdev, &req,
ptr, NULL, 1000, LIBUSB20_TRANSFER_SINGLE_SHORT_NOT_OK);
if (error) {
- return (error);
+ /* try to request full string */
+ req.wLength = 255;
+ flags = 0;
+ } else {
+ /* extract length and request full string */
+ req.wLength = *(uint8_t *)ptr;
+ flags = LIBUSB20_TRANSFER_SINGLE_SHORT_NOT_OK;
}
- req.wLength = *(uint8_t *)ptr; /* bytes */
if (req.wLength > len) {
/* partial string read */
req.wLength = len;
}
- error = libusb20_dev_request_sync(pdev, &req,
- ptr, NULL, 1000, LIBUSB20_TRANSFER_SINGLE_SHORT_NOT_OK);
-
- if (error) {
+ error = libusb20_dev_request_sync(pdev, &req, ptr, NULL, 1000, flags);
+ if (error)
return (error);
- }
- if (((uint8_t *)ptr)[1] != LIBUSB20_DT_STRING) {
+
+ if (((uint8_t *)ptr)[1] != LIBUSB20_DT_STRING)
return (LIBUSB20_ERROR_OTHER);
- }
return (0); /* success */
}
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