blob: 5716323ce6545f69bf6ee1937d0f53a60a85b28d [file] [log] [blame]
* Copyright (C) 2015 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include "diagnose_usb.h"
#include <errno.h>
#include <unistd.h>
#include <algorithm>
#include <string>
#include <vector>
#include <android-base/stringprintf.h>
#if defined(__linux__)
#include <grp.h>
#include <pwd.h>
static const char kPermissionsHelpUrl[] = "";
// Returns a message describing any potential problems we find with udev, or an empty string if we
// can't find plugdev information (i.e. udev is not installed).
static std::string GetUdevProblem() {
#if defined(__linux__) && !defined(__BIONIC__)
errno = 0;
group* plugdev_group = getgrnam("plugdev");
if (plugdev_group == nullptr) {
if (errno != 0) {
perror("failed to read plugdev group info");
// We can't give any generally useful advice here, just let the caller print the help URL.
return "";
int ngroups = getgroups(0, nullptr);
if (ngroups < 0) {
perror("failed to get groups list size");
return "";
std::vector<gid_t> groups(ngroups);
ngroups = getgroups(groups.size(),;
if (ngroups < 0) {
perror("failed to get groups list");
return "";
// getgroups(2) indicates that the egid may not be included so we check it additionally just
// to be sure.
if (std::find(groups.begin(), groups.end(), plugdev_group->gr_gid) != groups.end() ||
getegid() == plugdev_group->gr_gid) {
// The user is in plugdev so the problem is likely with the udev rules.
return "missing udev rules? user is in the plugdev group";
passwd* pwd = getpwuid(getuid());
return android::base::StringPrintf("user %s is not in the plugdev group",
pwd ? pwd->pw_name : "?");
return "";
// Short help text must be a single line, and will look something like:
// no permissions (reason); see [URL]
std::string UsbNoPermissionsShortHelpText() {
std::string help_text = "no permissions";
std::string problem(GetUdevProblem());
if (!problem.empty()) help_text += " (" + problem + ")";
return android::base::StringPrintf("%s; see [%s]", help_text.c_str(), kPermissionsHelpUrl);
// Long help text can span multiple lines but doesn't currently provide more detailed information:
// insufficient permissions for device: reason
// See [URL] for more information
std::string UsbNoPermissionsLongHelpText() {
std::string header = "insufficient permissions for device";
std::string problem(GetUdevProblem());
if (!problem.empty()) header += ": " + problem;
return android::base::StringPrintf("%s\nSee [%s] for more information", header.c_str(),