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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Helpers for querying USB properties from sysfs
*
* Copied from name.c which is:
* Copyright (C) 1999, 2000 Thomas Sailer (sailer@ife.ee.ethz.ch)
* Copyright (C) 2013 Tom Gundersen (teg@jklm.no)
*/
#include <stdint.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <linux/limits.h>
#include <libusb.h>
#include "sysfs.h"
/*
* The documentation of libusb_get_port_numbers() says "As per the USB 3.0
* specs, the current maximum limit for the depth is 7."
*/
#define USB_MAX_DEPTH 7
#define SYSFS_DEV_ATTR_PATH "/sys/bus/usb/devices/%s/%s"
int get_sysfs_name(char *buf, size_t size, libusb_device *dev)
{
int len = 0;
uint8_t bnum = libusb_get_bus_number(dev);
uint8_t pnums[USB_MAX_DEPTH];
int num_pnums;
buf[0] = '\0';
num_pnums = libusb_get_port_numbers(dev, pnums, sizeof(pnums));
if (num_pnums == LIBUSB_ERROR_OVERFLOW) {
return -1;
} else if (num_pnums == 0) {
/* Special-case root devices */
return snprintf(buf, size, "usb%d", bnum);
}
len += snprintf(buf, size, "%d-", bnum);
for (int i = 0; i < num_pnums; i++) {
int n = snprintf(buf + len, size - len, i ? ".%d" : "%d", pnums[i]);
if ((n < 0) || (n >= (int)(size - len)))
break;
len += n;
}
return len;
}
int read_sysfs_prop(char *buf, size_t size, const char *sysfs_name, const char *propname)
{
int n, fd;
char path[PATH_MAX];
buf[0] = '\0';
snprintf(path, sizeof(path), SYSFS_DEV_ATTR_PATH, sysfs_name, propname);
fd = open(path, O_RDONLY);
if (fd == -1)
return 0;
n = read(fd, buf, size);
if (n > 0)
buf[n-1] = '\0'; // Turn newline into null terminator
close(fd);
return n;
}
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