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      1 /*
      2  * Copyright (C) 2012-2014 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 <stdlib.h>
     18 
     19 #include <private/android_filesystem_config.h>
     20 
     21 #include "FlushCommand.h"
     22 #include "LogBuffer.h"
     23 #include "LogBufferElement.h"
     24 #include "LogCommand.h"
     25 #include "LogReader.h"
     26 #include "LogTimes.h"
     27 #include "LogUtils.h"
     28 
     29 FlushCommand::FlushCommand(LogReader& reader, bool nonBlock, unsigned long tail,
     30                            unsigned int logMask, pid_t pid, log_time start,
     31                            uint64_t timeout)
     32     : mReader(reader),
     33       mNonBlock(nonBlock),
     34       mTail(tail),
     35       mLogMask(logMask),
     36       mPid(pid),
     37       mStart(start),
     38       mTimeout((start != log_time::EPOCH) ? timeout : 0) {
     39 }
     40 
     41 // runSocketCommand is called once for every open client on the
     42 // log reader socket. Here we manage and associated the reader
     43 // client tracking and log region locks LastLogTimes list of
     44 // LogTimeEntrys, and spawn a transitory per-client thread to
     45 // work at filing data to the  socket.
     46 //
     47 // global LogTimeEntry::wrlock() is used to protect access,
     48 // reference counts are used to ensure that individual
     49 // LogTimeEntry lifetime is managed when not protected.
     50 void FlushCommand::runSocketCommand(SocketClient* client) {
     51     LogTimeEntry* entry = NULL;
     52     LastLogTimes& times = mReader.logbuf().mTimes;
     53 
     54     LogTimeEntry::wrlock();
     55     LastLogTimes::iterator it = times.begin();
     56     while (it != times.end()) {
     57         entry = (*it);
     58         if (entry->mClient == client) {
     59             if (entry->mTimeout.tv_sec || entry->mTimeout.tv_nsec) {
     60                 if (mReader.logbuf().isMonotonic()) {
     61                     LogTimeEntry::unlock();
     62                     return;
     63                 }
     64                 // If the user changes the time in a gross manner that
     65                 // invalidates the timeout, fall through and trigger.
     66                 log_time now(CLOCK_REALTIME);
     67                 if (((entry->mEnd + entry->mTimeout) > now) &&
     68                     (now > entry->mEnd)) {
     69                     LogTimeEntry::unlock();
     70                     return;
     71                 }
     72             }
     73             entry->triggerReader_Locked();
     74             if (entry->runningReader_Locked()) {
     75                 LogTimeEntry::unlock();
     76                 return;
     77             }
     78             entry->incRef_Locked();
     79             break;
     80         }
     81         it++;
     82     }
     83 
     84     if (it == times.end()) {
     85         // Create LogTimeEntry in notifyNewLog() ?
     86         if (mTail == (unsigned long)-1) {
     87             LogTimeEntry::unlock();
     88             return;
     89         }
     90         entry = new LogTimeEntry(mReader, client, mNonBlock, mTail, mLogMask,
     91                                  mPid, mStart, mTimeout);
     92         times.push_front(entry);
     93     }
     94 
     95     client->incRef();
     96 
     97     // release client and entry reference counts once done
     98     entry->startReader_Locked();
     99     LogTimeEntry::unlock();
    100 }
    101 
    102 bool FlushCommand::hasReadLogs(SocketClient* client) {
    103     return clientHasLogCredentials(client);
    104 }
    105 
    106 static bool clientHasSecurityCredentials(SocketClient* client) {
    107     return (client->getUid() == AID_SYSTEM) || (client->getGid() == AID_SYSTEM);
    108 }
    109 
    110 bool FlushCommand::hasSecurityLogs(SocketClient* client) {
    111     return clientHasSecurityCredentials(client);
    112 }
    113