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).
GetUdevProblem()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>
UsbNoPermissionsShortHelpText()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.
UsbNoPermissionsLongHelpText()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