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_protocol.h"
18 
19 #include <string.h>
20 
21 #include <algorithm>
22 
23 #include "adb_io.h"
24 
25 ShellProtocol::ShellProtocol(borrowed_fd 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