1 /**
2  * Copyright © 2020 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 
17 #include "journal.hpp"
18 
19 #include <errno.h>
20 #include <stdint.h>
21 #include <string.h>
22 #include <time.h>
23 
24 #include <chrono>
25 #include <stdexcept>
26 #include <thread>
27 
28 namespace phosphor::power::regulators
29 {
30 
31 /**
32  * @class JournalCloser
33  *
34  * Automatically closes the journal when the object goes out of scope.
35  */
36 class JournalCloser
37 {
38   public:
39     // Specify which compiler-generated methods we want
40     JournalCloser() = delete;
41     JournalCloser(const JournalCloser&) = delete;
42     JournalCloser(JournalCloser&&) = delete;
43     JournalCloser& operator=(const JournalCloser&) = delete;
44     JournalCloser& operator=(JournalCloser&&) = delete;
45 
46     explicit JournalCloser(sd_journal* journal) : journal{journal} {}
47 
48     ~JournalCloser()
49     {
50         sd_journal_close(journal);
51     }
52 
53   private:
54     sd_journal* journal{nullptr};
55 };
56 
57 std::vector<std::string> SystemdJournal::getMessages(
58     const std::string& field, const std::string& fieldValue, unsigned int max)
59 {
60     // Sleep 100ms; otherwise recent journal entries sometimes not available
61     using namespace std::chrono_literals;
62     std::this_thread::sleep_for(100ms);
63 
64     // Open the journal
65     sd_journal* journal;
66     int rc = sd_journal_open(&journal, SD_JOURNAL_LOCAL_ONLY);
67     if (rc < 0)
68     {
69         throw std::runtime_error{
70             std::string{"Failed to open journal: "} + strerror(-rc)};
71     }
72 
73     // Create object to automatically close journal
74     JournalCloser closer{journal};
75 
76     // Add match so we only loop over entries with specified field value
77     std::string match{field + '=' + fieldValue};
78     rc = sd_journal_add_match(journal, match.c_str(), 0);
79     if (rc < 0)
80     {
81         throw std::runtime_error{
82             std::string{"Failed to add journal match: "} + strerror(-rc)};
83     }
84 
85     // Loop through matching entries from newest to oldest
86     std::vector<std::string> messages;
87     messages.reserve((max != 0) ? max : 10);
88     std::string syslogID, pid, message, timeStamp, line;
89     SD_JOURNAL_FOREACH_BACKWARDS(journal)
90     {
91         // Get relevant journal entry fields
92         timeStamp = getTimeStamp(journal);
93         syslogID = getFieldValue(journal, "SYSLOG_IDENTIFIER");
94         pid = getFieldValue(journal, "_PID");
95         message = getFieldValue(journal, "MESSAGE");
96 
97         // Build one line string containing field values
98         line = timeStamp + " " + syslogID + "[" + pid + "]: " + message;
99         messages.emplace(messages.begin(), line);
100 
101         // Stop looping if a max was specified and we have reached it
102         if ((max != 0) && (messages.size() >= max))
103         {
104             break;
105         }
106     }
107 
108     return messages;
109 }
110 
111 std::string SystemdJournal::getFieldValue(sd_journal* journal,
112                                           const std::string& field)
113 {
114     std::string value{};
115 
116     // Get field data from current journal entry
117     const void* data{nullptr};
118     size_t length{0};
119     int rc = sd_journal_get_data(journal, field.c_str(), &data, &length);
120     if (rc < 0)
121     {
122         if (-rc == ENOENT)
123         {
124             // Current entry does not include this field; return empty value
125             return value;
126         }
127         else
128         {
129             throw std::runtime_error{
130                 std::string{"Failed to read journal entry field: "} +
131                 strerror(-rc)};
132         }
133     }
134 
135     // Get value from field data.  Field data in format "FIELD=value".
136     std::string dataString{static_cast<const char*>(data), length};
137     std::string::size_type pos = dataString.find('=');
138     if ((pos != std::string::npos) && ((pos + 1) < dataString.size()))
139     {
140         // Value is substring after the '='
141         value = dataString.substr(pos + 1);
142     }
143 
144     return value;
145 }
146 
147 std::string SystemdJournal::getTimeStamp(sd_journal* journal)
148 {
149     // Get realtime (wallclock) timestamp of current journal entry.  The
150     // timestamp is in microseconds since the epoch.
151     uint64_t usec{0};
152     int rc = sd_journal_get_realtime_usec(journal, &usec);
153     if (rc < 0)
154     {
155         throw std::runtime_error{
156             std::string{"Failed to get journal entry timestamp: "} +
157             strerror(-rc)};
158     }
159 
160     // Convert to number of seconds since the epoch
161     time_t secs = usec / 1000000;
162 
163     // Convert seconds to tm struct required by strftime()
164     struct tm* timeStruct = localtime(&secs);
165     if (timeStruct == nullptr)
166     {
167         throw std::runtime_error{
168             std::string{"Invalid journal entry timestamp: "} + strerror(errno)};
169     }
170 
171     // Convert tm struct into a date/time string
172     char timeStamp[80];
173     strftime(timeStamp, sizeof(timeStamp), "%b %d %H:%M:%S", timeStruct);
174 
175     return timeStamp;
176 }
177 
178 } // namespace phosphor::power::regulators
179