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/*
* find all usb-device interfaces, and make them available in a single string
*
* Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#define USB_DT_DEVICE 0x01
#define USB_DT_INTERFACE 0x04
static int devinfo(const char *syspath)
{
char filename[1024];
int fd;
ssize_t size;
unsigned char buf[18 + 65535];
unsigned int pos;
struct usb_interface_descriptor {
u_int8_t bLength;
u_int8_t bDescriptorType;
u_int8_t bInterfaceNumber;
u_int8_t bAlternateSetting;
u_int8_t bNumEndpoints;
u_int8_t bInterfaceClass;
u_int8_t bInterfaceSubClass;
u_int8_t bInterfaceProtocol;
u_int8_t iInterface;
};
strcpy(filename, "/sys");
strcat(filename, syspath);
strcat(filename, "/descriptors");
fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "error opening USB device 'descriptors' file\n");
return -1;
}
size = read(fd, buf, sizeof(buf));
close(fd);
if (size < 18 || size == sizeof(buf))
return -1;
printf("ID_USB_INTERFACES=:");
pos = 0;
while (pos < sizeof(buf)) {
struct usb_interface_descriptor *desc;
desc = (struct usb_interface_descriptor *) &buf[pos];
if (desc->bLength < 3)
break;
if (desc->bDescriptorType == USB_DT_INTERFACE)
printf("%02x%02x%02x:", desc->bInterfaceClass, desc->bInterfaceSubClass, desc->bInterfaceProtocol);
pos += desc->bLength;
}
printf("\n");
return 0;
}
int main(int argc, char *argv[])
{
const char *devpath = argv[1];
if (devpath == NULL) {
fprintf(stderr, "Usage: usbdev_id <devpath>\n");
return 1;
}
devinfo(devpath);
return 0;
}
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