119 lines
3.8 KiB
C++
119 lines
3.8 KiB
C++
/*
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* Copyright (C) 2015 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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#pragma once
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#include <stdint.h>
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#include <android-base/macros.h>
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#include "adb.h"
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#include "adb_unique_fd.h"
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// Class to send and receive shell protocol packets.
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//
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// To keep things simple and predictable, reads and writes block until an entire
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// packet is complete.
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//
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// Example: read raw data from |fd| and send it in a packet.
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// ShellProtocol* p = new ShellProtocol(protocol_fd);
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// int len = adb_read(stdout_fd, p->data(), p->data_capacity());
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// packet->WritePacket(ShellProtocol::kIdStdout, len);
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//
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// Example: read a packet and print it to |stdout|.
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// ShellProtocol* p = new ShellProtocol(protocol_fd);
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// if (p->ReadPacket() && p->id() == kIdStdout) {
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// fwrite(p->data(), 1, p->data_length(), stdout);
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// }
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class ShellProtocol {
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public:
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// This is an unscoped enum to make it easier to compare against raw bytes.
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enum Id : uint8_t {
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kIdStdin = 0,
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kIdStdout = 1,
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kIdStderr = 2,
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kIdExit = 3,
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// Close subprocess stdin if possible.
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kIdCloseStdin = 4,
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// Window size change (an ASCII version of struct winsize).
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kIdWindowSizeChange = 5,
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// Indicates an invalid or unknown packet.
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kIdInvalid = 255,
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};
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// ShellPackets will probably be too large to allocate on the stack so they
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// should be dynamically allocated on the heap instead.
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//
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// |fd| is an open file descriptor to be used to send or receive packets.
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explicit ShellProtocol(borrowed_fd fd);
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virtual ~ShellProtocol();
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// Returns a pointer to the data buffer.
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const char* data() const { return buffer_ + kHeaderSize; }
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char* data() { return buffer_ + kHeaderSize; }
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// Returns the total capacity of the data buffer.
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size_t data_capacity() const { return buffer_end_ - data(); }
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// Reads a packet from the FD.
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//
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// If a packet is too big to fit in the buffer then Read() will split the
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// packet across multiple calls. For example, reading a 50-byte packet into
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// a 20-byte buffer would read 20 bytes, 20 bytes, then 10 bytes.
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//
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// Returns false if the FD closed or errored.
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bool Read();
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// Returns the ID of the packet in the buffer.
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int id() const { return buffer_[0]; }
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// Returns the number of bytes that have been read into the data buffer.
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size_t data_length() const { return data_length_; }
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// Writes the packet currently in the buffer to the FD.
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//
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// Returns false if the FD closed or errored.
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bool Write(Id id, size_t length);
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private:
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// Packets support 4-byte lengths.
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typedef uint32_t length_t;
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enum {
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// It's OK if MAX_PAYLOAD doesn't match on the sending and receiving
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// end, reading will split larger packets into multiple smaller ones.
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kBufferSize = MAX_PAYLOAD,
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// Header is 1 byte ID + 4 bytes length.
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kHeaderSize = sizeof(Id) + sizeof(length_t)
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};
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borrowed_fd fd_;
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char buffer_[kBufferSize];
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size_t data_length_ = 0, bytes_left_ = 0;
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// We need to be able to modify this value for testing purposes, but it
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// will stay constant during actual program use.
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char* buffer_end_ = buffer_ + sizeof(buffer_);
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friend class ShellProtocolTest;
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DISALLOW_COPY_AND_ASSIGN(ShellProtocol);
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};
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