351ecd15b2
Background ========== On Windows, if you run "adb shell exit" in a loop in two windows, eventually the adb client will be unable to connect to the adb server. I think connect() is returning WSAEADDRINUSE: "Only one usage of each socket address (protocol/network address/port) is normally permitted. (10048)". The Windows System Event Log may also show Event 4227, Tcpip. Netstat output is filled with: # for the adb server TCP 127.0.0.1:5037 127.0.0.1:65523 TIME_WAIT # for the adb client TCP 127.0.0.1:65523 127.0.0.1:5037 TIME_WAIT The error probably means that the client is running out of free address:port pairs. The first netstat line is unavoidable, but the second line exists because the adb client is not waiting for orderly/graceful shutdown of the socket, and that is apparently required on Windows to get rid of the second line. For more info, see https://github.com/CompareAndSwap/SocketCloseTest . This is exacerbated by the fact that "adb shell exit" makes 4 socket connections to the adb server: 1) host:version, 2) host:features, 3) host:version (again), 4) shell:exit. Also exacerbating is the fact that the adb protocol is length-prefixed so the client typically does not have to 'read() until zero' which effectively waits for orderly/graceful shutdown. The Fix ======= Introduce a function, ReadOrderlyShutdown(), that should be called in the adb client to wait for the server to close its socket, before closing the client socket. I reviewed all code where the adb client makes a connection to the adb server and added ReadOrderlyShutdown() when it made sense. I wasn't able to add it to the following: * interactive_shell: this doesn't matter because this is interactive and thus can't be run fast enough to use up ports. * adb sideload: I couldn't get enough test coverage and I don't think this is being called frequently enough to be a problem. * send_shell_command, backup, adb_connect_command, adb shell, adb exec-out, install_multiple_app, adb_send_emulator_command: These already wait for server socket shutdown since they already call recv() until zero. * restore, adb exec-in: protocol design can't have the server close first. * adb start-server: no fd is actually returned * create_local_service_socket, local_connect_arbitrary_ports, connect_device: probably called rarely enough not to be a problem. Also in this change =================== * Clarify comments in when adb_shutdown() is called before exit(). * add some missing adb_close() in adb sideload. * Fixup error handling and comments in adb_send_emulator_command(). * Make SyncConnection::SendQuit return a success boolean. * Add unittest for adb emu kill command. This gets code coverage over this very careful piece of code. Change-Id: Iad0b1336f5b74186af2cd35f7ea827d0fa77a17c Signed-off-by: Spencer Low <CompareAndSwap@gmail.com>
76 lines
3 KiB
C++
76 lines
3 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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#ifndef ADB_IO_H
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#define ADB_IO_H
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#include <sys/types.h>
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#include <string>
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// Sends the protocol "OKAY" message.
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bool SendOkay(int fd);
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// Sends the protocol "FAIL" message, with the given failure reason.
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bool SendFail(int fd, const std::string& reason);
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// Writes a protocol-format string; a four hex digit length followed by the string data.
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bool SendProtocolString(int fd, const std::string& s);
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// Reads a protocol-format string; a four hex digit length followed by the string data.
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bool ReadProtocolString(int fd, std::string* s, std::string* error);
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// Reads exactly len bytes from fd into buf.
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//
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// Returns false if there is an error or if EOF was reached before len bytes
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// were read. If EOF was found, errno will be set to 0.
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//
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// If this function fails, the contents of buf are undefined.
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bool ReadFdExactly(int fd, void* buf, size_t len);
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// Given a client socket, wait for orderly/graceful shutdown. Call this:
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//
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// * Before closing a client socket.
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// * Only when no more data is expected to come in.
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// * Only when the server is not waiting for data from the client (because then
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// the client and server will deadlock waiting for each other).
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// * Only when the server is expected to close its socket right now.
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// * Don't call shutdown(SHUT_WR) before calling this because that will shutdown
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// the client socket early, defeating the purpose of calling this.
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//
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// Waiting for orderly/graceful shutdown of the server socket will cause the
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// server socket to close before the client socket. That prevents the client
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// socket from staying in TIME_WAIT which eventually causes subsequent
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// connect()s from the client to fail with WSAEADDRINUSE on Windows.
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// Returns true if it is sure that orderly/graceful shutdown has occurred with
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// no additional data read from the server.
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bool ReadOrderlyShutdown(int fd);
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// Writes exactly len bytes from buf to fd.
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//
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// Returns false if there is an error or if the fd was closed before the write
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// completed. If the other end of the fd (such as in a socket, pipe, or fifo),
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// is closed, errno will be set to 0.
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bool WriteFdExactly(int fd, const void* buf, size_t len);
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// Same as above, but for strings.
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bool WriteFdExactly(int fd, const char* s);
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bool WriteFdExactly(int fd, const std::string& s);
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// Same as above, but formats the string to send.
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bool WriteFdFmt(int fd, const char* fmt, ...) __attribute__((__format__(__printf__, 2, 3)));
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#endif /* ADB_IO_H */
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