194 lines
7.0 KiB
Java
194 lines
7.0 KiB
Java
/*
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* Copyright (C) 2012 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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package com.android.utils;
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import com.android.annotations.NonNull;
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import com.android.annotations.Nullable;
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import com.google.common.io.Closeables;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.InputStreamReader;
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public class GrabProcessOutput {
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public enum Wait {
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/**
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* Doesn't wait for the exec to complete.
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* This still monitors the output but does not wait for the process to finish.
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* In this mode the process return code is unknown and always 0.
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*/
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ASYNC,
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/**
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* This waits for the process to finish.
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* In this mode, {@link GrabProcessOutput#grabProcessOutput} returns the
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* error code from the process.
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* In some rare cases and depending on the OS, the process might not have
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* finished dumping data into stdout/stderr.
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* <p/>
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* Use this when you don't particularly care for the output but instead
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* care for the return code of the executed process.
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*/
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WAIT_FOR_PROCESS,
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/**
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* This waits for the process to finish <em>and</em> for the stdout/stderr
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* threads to complete.
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* In this mode, {@link GrabProcessOutput#grabProcessOutput} returns the
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* error code from the process.
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* <p/>
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* Use this one when capturing all the output from the process is important.
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*/
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WAIT_FOR_READERS,
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}
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public interface IProcessOutput {
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/**
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* Processes an stdout message line.
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* @param line The stdout message line. Null when the reader reached the end of stdout.
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*/
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void out(@Nullable String line);
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/**
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* Processes an stderr message line.
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* @param line The stderr message line. Null when the reader reached the end of stderr.
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*/
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void err(@Nullable String line);
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}
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/**
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* Get the stderr/stdout outputs of a process and return when the process is done.
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* Both <b>must</b> be read or the process will block on windows.
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*
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* @param process The process to get the output from.
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* @param output Optional object to capture stdout/stderr.
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* Note that on Windows capturing the output is not optional. If output is null
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* the stdout/stderr will be captured and discarded.
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* @param waitMode Whether to wait for the process and/or the readers to finish.
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* @return the process return code.
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* @throws InterruptedException if {@link Process#waitFor()} was interrupted.
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*/
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public static int grabProcessOutput(
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@NonNull final Process process,
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Wait waitMode,
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@Nullable final IProcessOutput output) throws InterruptedException {
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// read the lines as they come. if null is returned, it's
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// because the process finished
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Thread threadErr = new Thread("stderr") {
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@Override
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public void run() {
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// create a buffer to read the stderr output
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InputStream is = process.getErrorStream();
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InputStreamReader isr = new InputStreamReader(is);
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BufferedReader errReader = new BufferedReader(isr);
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try {
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while (true) {
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String line = errReader.readLine();
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if (output != null) {
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output.err(line);
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}
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if (line == null) {
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break;
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}
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}
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} catch (IOException e) {
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// do nothing.
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} finally {
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try {
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Closeables.close(is, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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try {
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Closeables.close(isr, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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try {
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Closeables.close(errReader, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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}
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}
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};
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Thread threadOut = new Thread("stdout") {
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@Override
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public void run() {
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InputStream is = process.getInputStream();
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InputStreamReader isr = new InputStreamReader(is);
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BufferedReader outReader = new BufferedReader(isr);
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try {
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while (true) {
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String line = outReader.readLine();
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if (output != null) {
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output.out(line);
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}
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if (line == null) {
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break;
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}
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}
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} catch (IOException e) {
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// do nothing.
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} finally {
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try {
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Closeables.close(is, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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try {
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Closeables.close(isr, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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try {
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Closeables.close(outReader, true /* swallowIOException */);
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} catch (IOException e) {
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// cannot happen
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}
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}
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}
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};
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threadErr.start();
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threadOut.start();
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if (waitMode == Wait.ASYNC) {
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return 0;
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}
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// it looks like on windows process#waitFor() can return
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// before the thread have filled the arrays, so we wait for both threads and the
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// process itself.
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if (waitMode == Wait.WAIT_FOR_READERS) {
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try {
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threadErr.join();
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} catch (InterruptedException e) {
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}
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try {
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threadOut.join();
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} catch (InterruptedException e) {
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}
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}
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// get the return code from the process
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return process.waitFor();
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}
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}
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