1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "diagnose_usb.h" 18 19 #include <errno.h> 20 #include <unistd.h> 21 22 #include <string> 23 24 #include <android-base/stringprintf.h> 25 26 #if defined(__linux__) 27 #include <grp.h> 28 #endif 29 30 static const char kPermissionsHelpUrl[] = "http://developer.android.com/tools/device.html"; 31 32 // Returns a message describing any potential problems we find with udev, or nullptr if we can't 33 // find plugdev information (i.e. udev is not installed). 34 static const char* GetUdevProblem() { 35 #if defined(__linux__) 36 errno = 0; 37 group* plugdev_group = getgrnam("plugdev"); 38 39 if (plugdev_group == nullptr) { 40 if (errno != 0) { 41 perror("failed to read plugdev group info"); 42 } 43 // We can't give any generally useful advice here, just let the caller print the help URL. 44 return nullptr; 45 } 46 47 // getgroups(2) indicates that the group_member() may not check the egid so we check it 48 // additionally just to be sure. 49 if (group_member(plugdev_group->gr_gid) || getegid() == plugdev_group->gr_gid) { 50 // The user is in plugdev so the problem is likely with the udev rules. 51 return "verify udev rules"; 52 } 53 return "udev requires plugdev group membership"; 54 #else 55 return nullptr; 56 #endif 57 } 58 59 // Short help text must be a single line, and will look something like: 60 // no permissions (reason); see <URL> 61 std::string UsbNoPermissionsShortHelpText() { 62 std::string help_text = "no permissions"; 63 64 const char* problem = GetUdevProblem(); 65 if (problem != nullptr) { 66 help_text += android::base::StringPrintf(" (%s)", problem); 67 } 68 69 return android::base::StringPrintf("%s; see [%s]", help_text.c_str(), kPermissionsHelpUrl); 70 } 71 72 // Long help text can span multiple lines and should provide more detailed information. 73 std::string UsbNoPermissionsLongHelpText() { 74 std::string header = "insufficient permissions for device"; 75 76 const char* problem = GetUdevProblem(); 77 if (problem != nullptr) { 78 header += android::base::StringPrintf(": %s", problem); 79 } 80 81 return android::base::StringPrintf("%s.\nSee [%s] for more information.", 82 header.c_str(), kPermissionsHelpUrl); 83 } 84
