1 /**
2  * Copyright © 2019 IBM Corporation
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 #include "log_id.hpp"
17 
18 #include "paths.hpp"
19 
20 #include <chrono>
21 #include <filesystem>
22 #include <fstream>
23 #include <phosphor-logging/log.hpp>
24 
25 namespace openpower
26 {
27 namespace pels
28 {
29 
30 namespace fs = std::filesystem;
31 using namespace phosphor::logging;
32 
33 constexpr uint32_t startingLogID = 1;
34 constexpr uint32_t bmcLogIDPrefix = 0x50000000;
35 
36 namespace detail
37 {
38 
39 uint32_t addLogIDPrefix(uint32_t id)
40 {
41     // If redundant BMCs are ever a thing, may need a different prefix.
42     return (id & 0x00FFFFFF) | bmcLogIDPrefix;
43 }
44 
45 uint32_t getTimeBasedLogID()
46 {
47     using namespace std::chrono;
48 
49     // Use 3 bytes of the nanosecond count since the epoch.
50     uint32_t id =
51         duration_cast<nanoseconds>(system_clock::now().time_since_epoch())
52             .count();
53 
54     return addLogIDPrefix(id);
55 }
56 
57 } // namespace detail
58 
59 uint32_t generatePELID()
60 {
61     // Note: there isn't a need to be thread safe.
62 
63     static std::string idFilename;
64     if (idFilename.empty())
65     {
66         idFilename = getPELIDFile();
67     }
68 
69     uint32_t id = 0;
70 
71     if (!fs::exists(idFilename))
72     {
73         auto path = fs::path(idFilename).parent_path();
74         if (!fs::exists(path))
75         {
76             fs::create_directories(path);
77         }
78 
79         id = startingLogID;
80     }
81     else
82     {
83         std::ifstream idFile{idFilename};
84         idFile >> id;
85         if (idFile.fail())
86         {
87             // Just make up an ID
88             log<level::ERR>("Unable to read PEL ID File!");
89             return detail::getTimeBasedLogID();
90         }
91     }
92 
93     // Wrapping shouldn't be a problem, but check anyway
94     if (id == 0x00FFFFFF)
95     {
96         id = startingLogID;
97     }
98 
99     std::ofstream idFile{idFilename};
100     idFile << (id + 1);
101     if (idFile.fail())
102     {
103         // Just make up an ID so we don't reuse one next time
104         log<level::ERR>("Unable to write PEL ID File!");
105         return detail::getTimeBasedLogID();
106     }
107 
108     return detail::addLogIDPrefix(id);
109 }
110 
111 } // namespace pels
112 } // namespace openpower
113