1/*
2 * Copyright (C) 2007 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
17package android.util;
18
19import java.io.BufferedReader;
20import java.io.FileReader;
21import java.io.IOException;
22import java.io.UnsupportedEncodingException;
23import java.nio.BufferUnderflowException;
24import java.nio.ByteBuffer;
25import java.nio.ByteOrder;
26import java.util.Collection;
27import java.util.HashMap;
28import java.util.regex.Matcher;
29import java.util.regex.Pattern;
30
31/**
32 * Access to the system diagnostic event record.  System diagnostic events are
33 * used to record certain system-level events (such as garbage collection,
34 * activity manager state, system watchdogs, and other low level activity),
35 * which may be automatically collected and analyzed during system development.
36 *
37 * <p>This is <b>not</b> the main "logcat" debugging log ({@link android.util.Log})!
38 * These diagnostic events are for system integrators, not application authors.
39 *
40 * <p>Events use integer tag codes corresponding to /system/etc/event-log-tags.
41 * They carry a payload of one or more int, long, or String values.  The
42 * event-log-tags file defines the payload contents for each type code.
43 */
44public class EventLog {
45    /** @hide */ public EventLog() {}
46
47    private static final String TAG = "EventLog";
48
49    private static final String TAGS_FILE = "/system/etc/event-log-tags";
50    private static final String COMMENT_PATTERN = "^\\s*(#.*)?$";
51    private static final String TAG_PATTERN = "^\\s*(\\d+)\\s+(\\w+)\\s*(\\(.*\\))?\\s*$";
52    private static HashMap<String, Integer> sTagCodes = null;
53    private static HashMap<Integer, String> sTagNames = null;
54
55    /** A previously logged event read from the logs. */
56    public static final class Event {
57        private final ByteBuffer mBuffer;
58
59        // Layout of event log entry received from kernel.
60        private static final int LENGTH_OFFSET = 0;
61        private static final int PROCESS_OFFSET = 4;
62        private static final int THREAD_OFFSET = 8;
63        private static final int SECONDS_OFFSET = 12;
64        private static final int NANOSECONDS_OFFSET = 16;
65
66        private static final int PAYLOAD_START = 20;
67        private static final int TAG_OFFSET = 20;
68        private static final int DATA_START = 24;
69
70        // Value types
71        private static final byte INT_TYPE    = 0;
72        private static final byte LONG_TYPE   = 1;
73        private static final byte STRING_TYPE = 2;
74        private static final byte LIST_TYPE   = 3;
75
76        /** @param data containing event, read from the system */
77        /*package*/ Event(byte[] data) {
78            mBuffer = ByteBuffer.wrap(data);
79            mBuffer.order(ByteOrder.nativeOrder());
80        }
81
82        /** @return the process ID which wrote the log entry */
83        public int getProcessId() {
84            return mBuffer.getInt(PROCESS_OFFSET);
85        }
86
87        /** @return the thread ID which wrote the log entry */
88        public int getThreadId() {
89            return mBuffer.getInt(THREAD_OFFSET);
90        }
91
92        /** @return the wall clock time when the entry was written */
93        public long getTimeNanos() {
94            return mBuffer.getInt(SECONDS_OFFSET) * 1000000000l
95                    + mBuffer.getInt(NANOSECONDS_OFFSET);
96        }
97
98        /** @return the type tag code of the entry */
99        public int getTag() {
100            return mBuffer.getInt(TAG_OFFSET);
101        }
102
103        /** @return one of Integer, Long, String, null, or Object[] of same. */
104        public synchronized Object getData() {
105            try {
106                mBuffer.limit(PAYLOAD_START + mBuffer.getShort(LENGTH_OFFSET));
107                mBuffer.position(DATA_START);  // Just after the tag.
108                return decodeObject();
109            } catch (IllegalArgumentException e) {
110                Log.wtf(TAG, "Illegal entry payload: tag=" + getTag(), e);
111                return null;
112            } catch (BufferUnderflowException e) {
113                Log.wtf(TAG, "Truncated entry payload: tag=" + getTag(), e);
114                return null;
115            }
116        }
117
118        /** @return the loggable item at the current position in mBuffer. */
119        private Object decodeObject() {
120            byte type = mBuffer.get();
121            switch (type) {
122            case INT_TYPE:
123                return (Integer) mBuffer.getInt();
124
125            case LONG_TYPE:
126                return (Long) mBuffer.getLong();
127
128            case STRING_TYPE:
129                try {
130                    int length = mBuffer.getInt();
131                    int start = mBuffer.position();
132                    mBuffer.position(start + length);
133                    return new String(mBuffer.array(), start, length, "UTF-8");
134                } catch (UnsupportedEncodingException e) {
135                    Log.wtf(TAG, "UTF-8 is not supported", e);
136                    return null;
137                }
138
139            case LIST_TYPE:
140                int length = mBuffer.get();
141                if (length < 0) length += 256;  // treat as signed byte
142                Object[] array = new Object[length];
143                for (int i = 0; i < length; ++i) array[i] = decodeObject();
144                return array;
145
146            default:
147                throw new IllegalArgumentException("Unknown entry type: " + type);
148            }
149        }
150    }
151
152    // We assume that the native methods deal with any concurrency issues.
153
154    /**
155     * Record an event log message.
156     * @param tag The event type tag code
157     * @param value A value to log
158     * @return The number of bytes written
159     */
160    public static native int writeEvent(int tag, int value);
161
162    /**
163     * Record an event log message.
164     * @param tag The event type tag code
165     * @param value A value to log
166     * @return The number of bytes written
167     */
168    public static native int writeEvent(int tag, long value);
169
170    /**
171     * Record an event log message.
172     * @param tag The event type tag code
173     * @param str A value to log
174     * @return The number of bytes written
175     */
176    public static native int writeEvent(int tag, String str);
177
178    /**
179     * Record an event log message.
180     * @param tag The event type tag code
181     * @param list A list of values to log
182     * @return The number of bytes written
183     */
184    public static native int writeEvent(int tag, Object... list);
185
186    /**
187     * Read events from the log, filtered by type.
188     * @param tags to search for
189     * @param output container to add events into
190     * @throws IOException if something goes wrong reading events
191     */
192    public static native void readEvents(int[] tags, Collection<Event> output)
193            throws IOException;
194
195    /**
196     * Get the name associated with an event type tag code.
197     * @param tag code to look up
198     * @return the name of the tag, or null if no tag has that number
199     */
200    public static String getTagName(int tag) {
201        readTagsFile();
202        return sTagNames.get(tag);
203    }
204
205    /**
206     * Get the event type tag code associated with an event name.
207     * @param name of event to look up
208     * @return the tag code, or -1 if no tag has that name
209     */
210    public static int getTagCode(String name) {
211        readTagsFile();
212        Integer code = sTagCodes.get(name);
213        return code != null ? code : -1;
214    }
215
216    /**
217     * Read TAGS_FILE, populating sTagCodes and sTagNames, if not already done.
218     */
219    private static synchronized void readTagsFile() {
220        if (sTagCodes != null && sTagNames != null) return;
221
222        sTagCodes = new HashMap<String, Integer>();
223        sTagNames = new HashMap<Integer, String>();
224
225        Pattern comment = Pattern.compile(COMMENT_PATTERN);
226        Pattern tag = Pattern.compile(TAG_PATTERN);
227        BufferedReader reader = null;
228        String line;
229
230        try {
231            reader = new BufferedReader(new FileReader(TAGS_FILE), 256);
232            while ((line = reader.readLine()) != null) {
233                if (comment.matcher(line).matches()) continue;
234
235                Matcher m = tag.matcher(line);
236                if (!m.matches()) {
237                    Log.wtf(TAG, "Bad entry in " + TAGS_FILE + ": " + line);
238                    continue;
239                }
240
241                try {
242                    int num = Integer.parseInt(m.group(1));
243                    String name = m.group(2);
244                    sTagCodes.put(name, num);
245                    sTagNames.put(num, name);
246                } catch (NumberFormatException e) {
247                    Log.wtf(TAG, "Error in " + TAGS_FILE + ": " + line, e);
248                }
249            }
250        } catch (IOException e) {
251            Log.wtf(TAG, "Error reading " + TAGS_FILE, e);
252            // Leave the maps existing but unpopulated
253        } finally {
254            try { if (reader != null) reader.close(); } catch (IOException e) {}
255        }
256    }
257}
258