1 /*
2 * Copyright (C) 2018 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 "server_configurable_flags/disaster_recovery.h"
18 #include "server_configurable_flags/get_flags.h"
19
20 #if defined(__BIONIC__)
21 #include <cutils/properties.h>
22 #endif // __BIONIC__
23 #include <regex>
24 #include <string>
25
26 #include "android-base/file.h"
27 #include "android-base/logging.h"
28 #include "android-base/properties.h"
29 #include "android-base/strings.h"
30 #include "android-base/unique_fd.h"
31
32 #define SYSTEM_PROPERTY_PREFIX "persist.device_config."
33
34 #define ATTEMPTED_BOOT_COUNT_PROPERTY "persist.device_config.attempted_boot_count"
35
36 #define RESET_PERFORMED_PROPERTY "device_config.reset_performed"
37
38 #define RESET_FLAGS_FILE_PATH "/data/server_configurable_flags/reset_flags"
39
40 #define ATTEMPTED_BOOT_COUNT_THRESHOLD 4
41
42 namespace server_configurable_flags {
43
44 static const std::regex NAME_VALID_CHARACTER_REGIX("^[\\w\\.\\-@:]*$");
45
MakeSystemPropertyName(const std::string & experiment_category_name,const std::string & experiment_flag_name)46 static std::string MakeSystemPropertyName(const std::string& experiment_category_name,
47 const std::string& experiment_flag_name) {
48 return SYSTEM_PROPERTY_PREFIX + experiment_category_name + "." + experiment_flag_name;
49 }
50
ValidateExperimentSegment(const std::string & segment)51 static bool ValidateExperimentSegment(const std::string& segment) {
52 return std::regex_match(segment, NAME_VALID_CHARACTER_REGIX) && segment.find(".") != 0 &&
53 segment.find(".") != segment.size() - 1;
54 }
55
56 #if defined(__BIONIC__)
ResetFlag(const char * key,const char * value,void * cookie)57 static void ResetFlag(const char* key, const char* value, void* cookie) {
58 if (strcmp(ATTEMPTED_BOOT_COUNT_PROPERTY, key) &&
59 android::base::StartsWith(key, SYSTEM_PROPERTY_PREFIX) && strlen(value) > 0 &&
60 android::base::SetProperty(key, "")) {
61 std::string* reset_flags = static_cast<std::string*>(cookie);
62 if (reset_flags->length() > 0) {
63 reset_flags->append(";");
64 }
65 reset_flags->append(key);
66 android::base::SetProperty(RESET_PERFORMED_PROPERTY, "true");
67 }
68 }
69
70 // Reset all system properties used as flags into empty value,
71 // and record reset flags' names in /data/server_configurable_flags/reset_flags
ResetAllFlags()72 static void ResetAllFlags() {
73 std::string reset_flags;
74 property_list(ResetFlag, &reset_flags);
75
76 if (reset_flags.length() > 0) {
77 android::base::unique_fd fd(
78 TEMP_FAILURE_RETRY(open(RESET_FLAGS_FILE_PATH, O_RDWR | O_CREAT | O_TRUNC, 0666)));
79 if (fd == -1) {
80 LOG(INFO) << __FUNCTION__ << " failed to open file " << RESET_FLAGS_FILE_PATH;
81 } else if (!WriteStringToFd(reset_flags, fd)) {
82 LOG(INFO) << __FUNCTION__ << " failed to write file " << RESET_FLAGS_FILE_PATH;
83 } else {
84 LOG(INFO) << __FUNCTION__ << " successfully write to file " << RESET_FLAGS_FILE_PATH;
85 }
86 }
87 }
88 #endif // __BIONIC__
89
ServerConfigurableFlagsReset(ResetMode reset_mode)90 void ServerConfigurableFlagsReset(ResetMode reset_mode) {
91 LOG(INFO) << __FUNCTION__ << " reset_mode value: " << reset_mode;
92 #if defined(__BIONIC__)
93 if (reset_mode == BOOT_FAILURE) {
94 int fail_count = android::base::GetIntProperty(ATTEMPTED_BOOT_COUNT_PROPERTY, 0);
95 if (fail_count < ATTEMPTED_BOOT_COUNT_THRESHOLD) {
96 LOG(INFO) << __FUNCTION__ << " attempted boot count is under threshold, skipping reset.";
97
98 // ATTEMPTED_BOOT_COUNT_PROPERTY will be reset to 0 when sys.boot_completed is set to 1.
99 // The code lives in flags_health_check.rc.
100 android::base::SetProperty(ATTEMPTED_BOOT_COUNT_PROPERTY, std::to_string(fail_count + 1));
101 } else {
102 LOG(INFO) << __FUNCTION__ << " attempted boot count reaches threshold, resetting flags.";
103 ResetAllFlags();
104 }
105 } else if (reset_mode == UPDATABLE_CRASHING) {
106 LOG(INFO) << __FUNCTION__ << " updatable crashing detected, resetting flags.";
107 ResetAllFlags();
108 } else {
109 LOG(ERROR) << __FUNCTION__ << " invalid reset_mode, skipping reset.";
110 }
111 #else
112 LOG(ERROR) << __FUNCTION__ << " ServerConfigurableFlagsReset is not available for this build.";
113 #endif // __BIONIC__
114 }
115
GetServerConfigurableFlag(const std::string & experiment_category_name,const std::string & experiment_flag_name,const std::string & default_value)116 std::string GetServerConfigurableFlag(const std::string& experiment_category_name,
117 const std::string& experiment_flag_name,
118 const std::string& default_value) {
119 if (!ValidateExperimentSegment(experiment_category_name)) {
120 LOG(ERROR) << __FUNCTION__ << " invalid category name " << experiment_category_name;
121 return default_value;
122 }
123 if (!ValidateExperimentSegment(experiment_flag_name)) {
124 LOG(ERROR) << __FUNCTION__ << " invalid flag name " << experiment_flag_name;
125 return default_value;
126 }
127 return android::base::GetProperty(
128 MakeSystemPropertyName(experiment_category_name, experiment_flag_name), default_value);
129 }
130
131 } // namespace server_configurable_flags
132