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      1 /*
      2  * Copyright (C) 2015 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 "shell_service.h"
     18 
     19 #include <string.h>
     20 
     21 #include <algorithm>
     22 
     23 #include "adb_io.h"
     24 
     25 ShellProtocol::ShellProtocol(int fd) : fd_(fd) {
     26     buffer_[0] = kIdInvalid;
     27 }
     28 
     29 ShellProtocol::~ShellProtocol() {
     30 }
     31 
     32 bool ShellProtocol::Read() {
     33     // Only read a new header if we've finished the last packet.
     34     if (!bytes_left_) {
     35         if (!ReadFdExactly(fd_, buffer_, kHeaderSize)) {
     36             return false;
     37         }
     38 
     39         length_t packet_length;
     40         memcpy(&packet_length, &buffer_[1], sizeof(packet_length));
     41         bytes_left_ = packet_length;
     42         data_length_ = 0;
     43     }
     44 
     45     size_t read_length = std::min(bytes_left_, data_capacity());
     46     if (read_length && !ReadFdExactly(fd_, data(), read_length)) {
     47         return false;
     48     }
     49 
     50     bytes_left_ -= read_length;
     51     data_length_ = read_length;
     52 
     53     return true;
     54 }
     55 
     56 bool ShellProtocol::Write(Id id, size_t length) {
     57     buffer_[0] = id;
     58     length_t typed_length = length;
     59     memcpy(&buffer_[1], &typed_length, sizeof(typed_length));
     60 
     61     return WriteFdExactly(fd_, buffer_, kHeaderSize + length);
     62 }
     63