5e001776f4
--wrap flag in logcat translates directly to the mTimeout inside logd, the value set is ANDROID_LOG_WRAP_DEFAULT_TIMEOUT defined in <log/log_read.h> as 7200 or 2 hours. For a non blocking read with a selected timeout, the logger waits until either the log buffer is about to 'wrap' and prune the log entry, or at the specified timeout. Non blocking in the logger context means that when there are no more log entries, the socket is closed. clock_gettime(CLOCK_REALTIME) is UTC 1970 epoch *NIX time. Is only affected for time updates, not timezone or daylight savings time. If there is a large user initiated time change, both the log entries and the timeout mentioned above really get called into question, so we trigger a release of the logs for clarity. This is so that the log reader can handle the disruptively updated time, and can immediately check the local time if necessary. The logger has a 5 second window for entries to land in time sorted order into the logging list. This should offer the log reader some differentiation between logging order sequence for monotonically increasing time, and sequence order in the face of user initiated time adjustments that break monotonicity. This change is about major time adjustments that can cause Fear, Uncertainty or Doubt about log entries. By returning, immediate action can be taken, rather than having to comb through the logs with less details about the time disruptions in hand. The least it can do is record what we have, and restart the call with a new tail time and timeout. Test: gTest liblog-unit-tests logcat-unit-test logd-unit-tests Bug: 35373582 Change-Id: I92cac83be99d68634ffd4ebd2f3a3067cfd0e942
112 lines
3.7 KiB
C++
112 lines
3.7 KiB
C++
/*
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* Copyright (C) 2012-2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <stdlib.h>
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#include <private/android_filesystem_config.h>
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#include "FlushCommand.h"
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#include "LogBuffer.h"
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#include "LogBufferElement.h"
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#include "LogCommand.h"
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#include "LogReader.h"
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#include "LogTimes.h"
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#include "LogUtils.h"
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FlushCommand::FlushCommand(LogReader& reader, bool nonBlock, unsigned long tail,
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unsigned int logMask, pid_t pid, log_time start,
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uint64_t timeout)
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: mReader(reader),
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mNonBlock(nonBlock),
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mTail(tail),
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mLogMask(logMask),
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mPid(pid),
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mStart(start),
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mTimeout((start != log_time::EPOCH) ? timeout : 0) {
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}
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// runSocketCommand is called once for every open client on the
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// log reader socket. Here we manage and associated the reader
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// client tracking and log region locks LastLogTimes list of
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// LogTimeEntrys, and spawn a transitory per-client thread to
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// work at filing data to the socket.
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//
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// global LogTimeEntry::lock() is used to protect access,
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// reference counts are used to ensure that individual
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// LogTimeEntry lifetime is managed when not protected.
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void FlushCommand::runSocketCommand(SocketClient* client) {
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LogTimeEntry* entry = NULL;
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LastLogTimes& times = mReader.logbuf().mTimes;
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LogTimeEntry::lock();
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LastLogTimes::iterator it = times.begin();
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while (it != times.end()) {
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entry = (*it);
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if (entry->mClient == client) {
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if (entry->mTimeout.tv_sec || entry->mTimeout.tv_nsec) {
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if (mReader.logbuf().isMonotonic()) {
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LogTimeEntry::unlock();
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return;
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}
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// If the user changes the time in a gross manner that
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// invalidates the timeout, fall through and trigger.
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log_time now(CLOCK_REALTIME);
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if (((entry->mEnd + entry->mTimeout) > now) &&
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(now > entry->mEnd)) {
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LogTimeEntry::unlock();
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return;
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}
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}
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entry->triggerReader_Locked();
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if (entry->runningReader_Locked()) {
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LogTimeEntry::unlock();
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return;
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}
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entry->incRef_Locked();
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break;
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}
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it++;
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}
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if (it == times.end()) {
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// Create LogTimeEntry in notifyNewLog() ?
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if (mTail == (unsigned long)-1) {
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LogTimeEntry::unlock();
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return;
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}
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entry = new LogTimeEntry(mReader, client, mNonBlock, mTail, mLogMask,
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mPid, mStart, mTimeout);
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times.push_front(entry);
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}
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client->incRef();
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// release client and entry reference counts once done
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entry->startReader_Locked();
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LogTimeEntry::unlock();
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}
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bool FlushCommand::hasReadLogs(SocketClient* client) {
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return clientHasLogCredentials(client);
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}
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static bool clientHasSecurityCredentials(SocketClient* client) {
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return (client->getUid() == AID_SYSTEM) || (client->getGid() == AID_SYSTEM);
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}
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bool FlushCommand::hasSecurityLogs(SocketClient* client) {
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return clientHasSecurityCredentials(client);
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}
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