Problem with libusb20_dev_get_port_path()

[Uffe Jakobsen]

On 2015-01-20 05:35, Hans Petter Selasky wrote:
> On 01/20/15 00:33, Uffe Jakobsen wrote:
>>
>> I seem to be having a problem with libusb20_dev_get_port_path()
>>
>> I iterate through all usb devices in the system.
>> libusb20_dev_get_port_path() returns 0 for all my usb devices.
>>
>> Any hints ?
>>
>> Seen on FreeBSD 10.1 (amd64) with latest patches
>
> Did you do a:
>
> libusb20_dev_open()
>
> first?
>

yes - without that I get an error (negative return code)

Running as root does not change anything (I didn't expect that - but I 
had to try)

Stripped sample code below produces the following output:

# ./a.out
BEGIN
device descriptor: 'ugen0.1: <UHCI root HUB Intel> at usbus0'
get_port_path: 0

device descriptor: 'ugen2.1: <UHCI root HUB Intel> at usbus2'
get_port_path: 0

device descriptor: 'ugen1.1: <UHCI root HUB Intel> at usbus1'
get_port_path: 0

device descriptor: 'ugen4.1: <EHCI root HUB Intel> at usbus4'
get_port_path: 0

device descriptor: 'ugen3.1: <UHCI root HUB Intel> at usbus3'
get_port_path: 0

device descriptor: 'ugen3.2: <USB CAT5 vendor 0x0d3d> at usbus3'
get_port_path: 0

END


//
// Compile: cc tst.c -lusb
//

#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <limits.h>
#include <stdio.h>

#include <libusb20.h>


int main(int argc, char** argv)
{
   int rc;
   struct libusb20_backend* pbe;
   struct libusb20_device* pdev_curr;
   struct libusb20_device* pdev_last;
   uint8_t usb_ports[UINT8_MAX];
   char sbuf[FILENAME_MAX];
   char *p_str;

   printf("BEGIN\n");
   pbe = libusb20_be_alloc_default();
   pdev_curr = pdev_last = NULL;
   do {
     pdev_curr = libusb20_be_device_foreach(pbe, pdev_last);
     if (pdev_curr == NULL) {
       break;
     }
     libusb20_dev_open(pdev_curr, 0);
     p_str = (char*)libusb20_dev_get_desc(pdev_curr);
     printf("device descriptor: '%s'\n", p_str);
     rc = libusb20_dev_get_port_path(pdev_curr, (uint8_t*)&usb_ports, 
UINT8_MAX);
     printf("get_port_path: %d\n", rc);
     printf("\n");
     libusb20_dev_close(pdev_curr);

     pdev_last = pdev_curr;
   } while (pdev_curr != NULL);

   libusb20_be_free(pbe);
   printf("END\n");
   return 0;
}


//
// EOF
//


/Uffe