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      1 /*
      2  * Copyright 2018, 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 "commander.h"
     18 
     19 #include "commands/command.h"
     20 #include "log.h"
     21 
     22 #include <errno.h>
     23 #pragma clang diagnostic push
     24 #pragma clang diagnostic ignored "-Wunused-function"
     25 #include <qemu_pipe.h>
     26 #pragma clang diagnostic pop
     27 #include <string.h>
     28 #include <sys/socket.h>
     29 #include <sys/types.h>
     30 
     31 static const char kQemuPipeName[] = "qemud:network";
     32 
     33 // How much space to use for each command received
     34 static const size_t kReceiveSpace = 1024;
     35 // The maximum amount of bytes to keep in the receive buffer for a single
     36 // command before dropping data.
     37 static const size_t kMaxReceiveBufferSize = 65536;
     38 
     39 Commander::Commander() : mPipeFd(-1) {
     40 }
     41 
     42 Commander::~Commander() {
     43     closePipe();
     44 }
     45 
     46 Result Commander::init() {
     47     if (mPipeFd != -1) {
     48         return Result::error("Commander already initialized");
     49     }
     50 
     51     openPipe();
     52 
     53     return Result::success();
     54 }
     55 
     56 void Commander::registerCommand(const char* commandStr, Command* command) {
     57     mCommands[commandStr] = command;
     58 }
     59 
     60 void Commander::getPollData(std::vector<pollfd>* fds) const {
     61     if (mPipeFd != -1) {
     62         fds->push_back(pollfd{mPipeFd, POLLIN, 0});
     63     }
     64 }
     65 
     66 Pollable::Timestamp Commander::getTimeout() const {
     67     return mDeadline;
     68 }
     69 
     70 bool Commander::onReadAvailable(int /*fd*/, int* /*status*/) {
     71     size_t offset = mReceiveBuffer.size();
     72     mReceiveBuffer.resize(offset + kReceiveSpace);
     73     if (mReceiveBuffer.size() > kMaxReceiveBufferSize) {
     74         // We have buffered too much data, this should never happen but as a
     75         // seurity measure let's just drop everything we have and keep
     76         // receiving. Maybe the situation will improve.
     77         mReceiveBuffer.resize(kReceiveSpace);
     78         offset = 0;
     79     }
     80     while (true) {
     81         int status = ::read(mPipeFd, &mReceiveBuffer[offset], kReceiveSpace);
     82 
     83         if (status < 0) {
     84             if (errno == EINTR) {
     85                 // We got an interrupt, try again
     86                 continue;
     87             }
     88             LOGE("Commander failed to receive on pipe: %s", strerror(errno));
     89             // Don't exit the looper because of this, keep trying
     90             return true;
     91         }
     92         size_t length = static_cast<size_t>(status);
     93         mReceiveBuffer.resize(offset + length);
     94 
     95         while (true) {
     96             auto endline = std::find(mReceiveBuffer.begin(),
     97                                      mReceiveBuffer.end(),
     98                                      '\n');
     99             if (endline == mReceiveBuffer.end()) {
    100                 // No endline in sight, keep waiting and buffering
    101                 return true;
    102             }
    103 
    104             *endline = '\0';
    105 
    106             char* args = ::strchr(mReceiveBuffer.data(), ' ');
    107             if (args) {
    108                 *args++ = '\0';
    109             }
    110             auto command = mCommands.find(mReceiveBuffer.data());
    111 
    112             if (command != mCommands.end()) {
    113                 command->second->onCommand(mReceiveBuffer.data(), args);
    114             }
    115             // Now that we have processed this line let's remove it from the
    116             // receive buffer
    117             ++endline;
    118             if (endline == mReceiveBuffer.end()) {
    119                 mReceiveBuffer.clear();
    120                 // There can be nothing left, just return
    121                 return true;
    122             } else {
    123                 mReceiveBuffer.erase(mReceiveBuffer.begin(), endline + 1);
    124                 // There may be another line in there so keep looping and look
    125                 // for more
    126             }
    127         }
    128         return true;
    129     }
    130 }
    131 
    132 bool Commander::onClose(int /*fd*/, int* /*status*/) {
    133     // Pipe was closed from the other end, close it on our side and re-open
    134     closePipe();
    135     openPipe();
    136     return true;
    137 }
    138 
    139 bool Commander::onTimeout(int* /*status*/) {
    140     if (mPipeFd == -1) {
    141         openPipe();
    142     }
    143     return true;
    144 }
    145 
    146 void Commander::openPipe() {
    147     mPipeFd = qemu_pipe_open(kQemuPipeName);
    148     if (mPipeFd == -1) {
    149         LOGE("Failed to open QEMU pipe '%s': %s",
    150              kQemuPipeName,
    151              strerror(errno));
    152         // Try again in the future
    153         mDeadline = Pollable::Clock::now() + std::chrono::minutes(1);
    154     } else {
    155         mDeadline = Pollable::Timestamp::max();
    156     }
    157 }
    158 
    159 void Commander::closePipe() {
    160     if (mPipeFd != -1) {
    161         ::close(mPipeFd);
    162         mPipeFd = -1;
    163     }
    164 }
    165