// Copyright 2014 The Bazel Authors. All rights reserved. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. package com.google.devtools.build.lib.shell; import com.google.common.collect.ImmutableList; import com.google.devtools.build.lib.shell.SubprocessBuilder.StreamAction; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.List; import java.util.Map; import java.util.logging.Level; import java.util.logging.Logger; /** *

Represents an executable command, including its arguments and * runtime environment (environment variables, working directory). This class * lets a caller execute a command, get its results, and optionally try to kill * the task during execution.

* *

The use of "shell" in the full name of this class is a misnomer. In * terms of the way its arguments are interpreted, this class is closer to * {@code execve(2)} than to {@code system(3)}. No Bourne shell is executed. * *

The most basic use-case for this class is as follows: *

 *   String[] args = { "/bin/du", "-s", directory };
 *   CommandResult result = new Command(args).execute();
 *   String output = new String(result.getStdout());
 * 
* which writes the output of the {@code du(1)} command into {@code output}. * More complex cases might inspect the stderr stream, kill the subprocess * asynchronously, feed input to its standard input, handle the exceptions * thrown if the command fails, or print the termination status (exit code or * signal name). * *

Invoking the Bourne shell

* *

Perhaps the most common command invoked programmatically is the UNIX * shell, {@code /bin/sh}. Because the shell is a general-purpose programming * language, care must be taken to ensure that variable parts of the shell * command (e.g. strings entered by the user) do not contain shell * metacharacters, as this poses a correctness and/or security risk. * *

To execute a shell command directly, use the following pattern: *

 *   String[] args = { "/bin/sh", "-c", shellCommand };
 *   CommandResult result = new Command(args).execute();
 * 
* {@code shellCommand} is a complete Bourne shell program, possibly containing * all kinds of unescaped metacharacters. For example, here's a shell command * that enumerates the working directories of all processes named "foo": *
ps auxx | grep foo | awk '{print $1}' |
 *      while read pid; do readlink /proc/$pid/cwd; done
* It is the responsibility of the caller to ensure that this string means what * they intend. * *

Consider the risk posed by allowing the "foo" part of the previous * command to be some arbitrary (untrusted) string called {@code processName}: *

 *  // WARNING: unsafe!
 *  String shellCommand = "ps auxx | grep " + processName + " | awk '{print $1}' | "
 *  + "while read pid; do readlink /proc/$pid/cwd; done";
* * Passing this string to {@link Command} is unsafe because if the string * {@processName} contains shell metacharacters, the meaning of the command can * be arbitrarily changed; consider: *
String processName = ". ; rm -fr $HOME & ";
* *

To defend against this possibility, it is essential to properly quote the * variable portions of the shell command so that shell metacharacters are * escaped. Use {@link ShellUtils#shellEscape} for this purpose: *

 *  // Safe.
 *  String shellCommand = "ps auxx | grep " + ShellUtils.shellEscape(processName)
 *      + " | awk '{print $1}' | while read pid; do readlink /proc/$pid/cwd; done";
 * 
* *

Tip: if you are only invoking a single known command, and no shell * features (e.g. $PATH lookup, output redirection, pipelines, etc) are needed, * call it directly without using a shell, as in the {@code du(1)} example * above. * *

Other features

* *

A caller can optionally specify bytes to be written to the process's * "stdin". The returned {@link CommandResult} object gives the caller access to * the exit status, as well as output from "stdout" and "stderr". To use * this class with processes that generate very large amounts of input/output, * consider * {@link #execute(InputStream, KillableObserver, OutputStream, OutputStream)} * and * {@link #execute(byte[], KillableObserver, OutputStream, OutputStream)}. *

* *

This class ensures that stdout and stderr streams are read promptly, * avoiding potential deadlock if the output is large. See When * Runtime.exec() won't.

* *

This class is immutable and therefore thread-safe.

*/ public final class Command { private static final Logger log = Logger.getLogger("com.google.devtools.build.lib.shell.Command"); /** * Pass this value to {@link #execute(byte[])} to indicate that no input * should be written to stdin. */ public static final byte[] NO_INPUT = new byte[0]; /** * Pass this to {@link #execute(byte[], KillableObserver, boolean)} to * indicate that you do not wish to observe / kill the underlying * process. */ public static final KillableObserver NO_OBSERVER = new KillableObserver() { @Override public void startObserving(final Killable killable) { // do nothing } @Override public void stopObserving(final Killable killable) { // do nothing } }; private final SubprocessBuilder subprocessBuilder; // Start of public API ----------------------------------------------------- /** /** * Creates a new {@link Command} for the given command line elements. The * command line is executed exactly as given, without a shell. * Subsequent calls to {@link #execute()} will use the JVM's working * directory and environment. * * @param commandLineElements elements of raw command line to execute * @throws IllegalArgumentException if commandLine is null or empty */ /* TODO(bazel-team): Use varargs here */ public Command(final String[] commandLineElements) { this(commandLineElements, null, null); } /** * Just like {@link Command(String, Map, File, long), but without a timeout. */ public Command( String[] commandLineElements, Map environmentVariables, File workingDirectory) { this(commandLineElements, environmentVariables, workingDirectory, -1); } /** * Creates a new {@link Command} for the given command line elements. The * command line is executed without a shell. * * The given environment variables and working directory are used in subsequent * calls to {@link #execute()}. * * This command treats the 0-th element of {@code commandLineElement} * (the name of an executable to run) specially. * * * @param commandLineElements elements of raw command line to execute * @param environmentVariables environment variables to replace JVM's * environment variables; may be null * @param workingDirectory working directory for execution; if null, current * working directory is used * @param timeoutMillis timeout in milliseconds. Only supported on Windows. * @throws IllegalArgumentException if commandLine is null or empty */ public Command( String[] commandLineElements, Map environmentVariables, File workingDirectory, long timeoutMillis) { if (commandLineElements == null || commandLineElements.length == 0) { throw new IllegalArgumentException("command line is null or empty"); } File executable = new File(commandLineElements[0]); if (!executable.isAbsolute() && executable.getParent() != null) { commandLineElements = commandLineElements.clone(); commandLineElements[0] = new File(workingDirectory, commandLineElements[0]).getAbsolutePath(); } this.subprocessBuilder = new SubprocessBuilder(); subprocessBuilder.setArgv(ImmutableList.copyOf(commandLineElements)); subprocessBuilder.setEnv(environmentVariables); subprocessBuilder.setWorkingDirectory(workingDirectory); subprocessBuilder.setTimeoutMillis(timeoutMillis); } /** * @return raw command line elements to be executed */ public String[] getCommandLineElements() { final List elements = subprocessBuilder.getArgv(); return elements.toArray(new String[elements.size()]); } /** * @return (unmodifiable) {@link Map} view of command's environment variables */ public Map getEnvironmentVariables() { return subprocessBuilder.getEnv(); } /** * @return working directory used for execution, or null if the current * working directory is used */ public File getWorkingDirectory() { return subprocessBuilder.getWorkingDirectory(); } /** * Execute this command with no input to stdin. This call will block until the * process completes or an error occurs. * * @return {@link CommandResult} representing result of the execution * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if an {@link IOException} is * encountered while reading from the process, or the process was terminated * due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status */ public CommandResult execute() throws CommandException { return execute(NO_INPUT); } /** * Execute this command with given input to stdin. This call will block until * the process completes or an error occurs. * * @param stdinInput bytes to be written to process's stdin * @return {@link CommandResult} representing result of the execution * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if an {@link IOException} is * encountered while reading from the process, or the process was terminated * due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status * @throws NullPointerException if stdin is null */ public CommandResult execute(final byte[] stdinInput) throws CommandException { nullCheck(stdinInput, "stdinInput"); return doExecute(new ByteArrayInputSource(stdinInput), NO_OBSERVER, Consumers.createAccumulatingConsumers(), /*killSubprocess=*/false, /*closeOutput=*/false).get(); } /** *

Execute this command with given input to stdin. This call will block * until the process completes or an error occurs. Caller may specify * whether the method should ignore stdout/stderr output. If the * given number of milliseconds elapses before the command has * completed, this method will attempt to kill the command.

* * @param stdinInput bytes to be written to process's stdin, or * {@link #NO_INPUT} if no bytes should be written * @param timeout number of milliseconds to wait for command completion * before attempting to kill the command * @param ignoreOutput if true, method will ignore stdout/stderr output * and return value will not contain this data * @return {@link CommandResult} representing result of the execution * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if an {@link IOException} is * encountered while reading from the process, or the process was terminated * due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status * @throws NullPointerException if stdin is null */ public CommandResult execute(final byte[] stdinInput, final long timeout, final boolean ignoreOutput) throws CommandException { return execute(stdinInput, new TimeoutKillableObserver(timeout), ignoreOutput); } /** *

Execute this command with given input to stdin. This call will block * until the process completes or an error occurs. Caller may specify * whether the method should ignore stdout/stderr output. The given {@link * KillableObserver} may also terminate the process early while running.

* * @param stdinInput bytes to be written to process's stdin, or * {@link #NO_INPUT} if no bytes should be written * @param observer {@link KillableObserver} that should observe the running * process, or {@link #NO_OBSERVER} if caller does not wish to kill * the process * @param ignoreOutput if true, method will ignore stdout/stderr output * and return value will not contain this data * @return {@link CommandResult} representing result of the execution * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if the process is interrupted (or * killed) before completion, if an {@link IOException} is encountered while * reading from the process, or the process was terminated due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status * @throws NullPointerException if stdin is null */ public CommandResult execute(final byte[] stdinInput, final KillableObserver observer, final boolean ignoreOutput) throws CommandException { // supporting "null" here for backwards compatibility final KillableObserver theObserver = observer == null ? NO_OBSERVER : observer; return doExecute(new ByteArrayInputSource(stdinInput), theObserver, ignoreOutput ? Consumers.createDiscardingConsumers() : Consumers.createAccumulatingConsumers(), /*killSubprocess=*/false, /*closeOutput=*/false).get(); } /** *

Execute this command with given input to stdin. This call blocks * until the process completes or an error occurs. The caller provides * {@link OutputStream} instances into which the process writes its * stdout/stderr output; these streams are not closed when the * process terminates. The given {@link KillableObserver} may also * terminate the process early while running.

* *

Note that stdout and stderr are written concurrently. If these are * aliased to each other, it is the caller's duty to ensure thread safety. *

* * @param stdinInput bytes to be written to process's stdin, or * {@link #NO_INPUT} if no bytes should be written * @param observer {@link KillableObserver} that should observe the running * process, or {@link #NO_OBSERVER} if caller does not wish to kill the * process * @param stdOut the process will write its standard output into this stream. * E.g., you could pass {@link System#out} as stdOut. * @param stdErr the process will write its standard error into this stream. * E.g., you could pass {@link System#err} as stdErr. * @return {@link CommandResult} representing result of the execution. Note * that {@link CommandResult#getStdout()} and * {@link CommandResult#getStderr()} will yield {@link IllegalStateException} * in this case, as the output is written to stdOut/stdErr * instead. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if the process is interrupted (or * killed) before completion, if an {@link IOException} is encountered while * reading from the process, or the process was terminated due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status * @throws NullPointerException if any argument is null. */ public CommandResult execute(final byte[] stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr) throws CommandException { return execute(stdinInput, observer, stdOut, stdErr, false); } /** * Like {@link #execute(byte[], KillableObserver, OutputStream, OutputStream)} * but enables setting of the killSubprocessOnInterrupt attribute. * * @param killSubprocessOnInterrupt if set to true, the execution of * this command is interruptible: in other words, if this thread is * interrupted during a call to execute, the subprocess will be terminated * and the call will return in a timely manner. If false, the subprocess * will run to completion; this is the default value use by all other * constructors. The thread's interrupted status is preserved in all cases, * however. */ public CommandResult execute(final byte[] stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr, final boolean killSubprocessOnInterrupt) throws CommandException { nullCheck(stdinInput, "stdinInput"); nullCheck(observer, "observer"); nullCheck(stdOut, "stdOut"); nullCheck(stdErr, "stdErr"); return doExecute(new ByteArrayInputSource(stdinInput), observer, Consumers.createStreamingConsumers(stdOut, stdErr), killSubprocessOnInterrupt, false).get(); } /** * Execute this command with given input to stdin; this stream is closed when the process * terminates, and exceptions raised when closing this stream are ignored. This call blocks until * the process completes or an error occurs. The caller provides {@link OutputStream} instances * into which the process writes its stdout/stderr output; these streams are not closed * when the process terminates. The given {@link KillableObserver} may also terminate the process * early while running. * *

If stdOut or stdErr is {@code null}, it will be redirected to /dev/null. */ public CommandResult execute( final byte[] stdinInput, final KillableObserver observer, final File stdOut, final File stdErr, final boolean killSubprocessOnInterrupt) throws CommandException { nullCheck(stdinInput, "stdinInput"); nullCheck(observer, "observer"); if (stdOut == null) { subprocessBuilder.setStdout(StreamAction.DISCARD); } else { subprocessBuilder.setStdout(stdOut); } if (stdErr == null) { subprocessBuilder.setStderr(StreamAction.DISCARD); } else { subprocessBuilder.setStderr(stdErr); } return doExecute( new ByteArrayInputSource(stdinInput), observer, null, killSubprocessOnInterrupt, false) .get(); } /** * Execute this command with given input to stdin; this stream is closed when the process * terminates, and exceptions raised when closing this stream are ignored. This call blocks until * the process completes or an error occurs. The caller provides {@link OutputStream} instances * into which the process writes its stdout/stderr output; these streams are not closed * when the process terminates. The given {@link KillableObserver} may also terminate the process * early while running. * * @param stdinInput The input to this process's stdin * @param observer {@link KillableObserver} that should observe the running process, or {@link * #NO_OBSERVER} if caller does not wish to kill the process * @param stdOut the process will write its standard output into this stream. E.g., you could pass * {@link System#out} as stdOut. * @param stdErr the process will write its standard error into this stream. E.g., you could pass * {@link System#err} as stdErr. * @return {@link CommandResult} representing result of the execution. Note that {@link * CommandResult#getStdout()} and {@link CommandResult#getStderr()} will yield {@link * IllegalStateException} in this case, as the output is written to stdOut/stdErr * instead. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any reason * @throws AbnormalTerminationException if the process is interrupted (or killed) before * completion, if an {@link IOException} is encountered while reading from the process, or the * process was terminated due to a signal. * @throws BadExitStatusException if the process exits with a non-zero status * @throws NullPointerException if any argument is null. */ public CommandResult execute( final InputStream stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr) throws CommandException { nullCheck(stdinInput, "stdinInput"); nullCheck(observer, "observer"); nullCheck(stdOut, "stdOut"); nullCheck(stdErr, "stdErr"); return doExecute(new InputStreamInputSource(stdinInput), observer, Consumers.createStreamingConsumers(stdOut, stdErr), /*killSubprocess=*/false, /*closeOutput=*/false).get(); } /** *

Execute this command with given input to stdin; this stream is closed * when the process terminates, and exceptions raised when closing this * stream are ignored. This call blocks * until the process completes or an error occurs. The caller provides * {@link OutputStream} instances into which the process writes its * stdout/stderr output; these streams are closed when the process terminates * if closeOut is set. The given {@link KillableObserver} may also * terminate the process early while running.

* * @param stdinInput The input to this process's stdin * @param observer {@link KillableObserver} that should observe the running * process, or {@link #NO_OBSERVER} if caller does not wish to kill the * process * @param stdOut the process will write its standard output into this stream. * E.g., you could pass {@link System#out} as stdOut. * @param stdErr the process will write its standard error into this stream. * E.g., you could pass {@link System#err} as stdErr. * @param closeOut whether to close the output streams when the subprocess * terminates. * @return {@link CommandResult} representing result of the execution. Note * that {@link CommandResult#getStdout()} and * {@link CommandResult#getStderr()} will yield {@link IllegalStateException} * in this case, as the output is written to stdOut/stdErr * instead. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws AbnormalTerminationException if the process is interrupted (or * killed) before completion, if an {@link IOException} is encountered while * reading from the process, or the process was terminated due to a signal. * @throws BadExitStatusException if the process exits with a * non-zero status * @throws NullPointerException if any argument is null. */ public CommandResult execute(final InputStream stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr, boolean closeOut) throws CommandException { nullCheck(stdinInput, "stdinInput"); nullCheck(observer, "observer"); nullCheck(stdOut, "stdOut"); nullCheck(stdErr, "stdErr"); return doExecute(new InputStreamInputSource(stdinInput), observer, Consumers.createStreamingConsumers(stdOut, stdErr), false, closeOut).get(); } /** * Executes this command with the given stdinInput, but does not wait for it to complete. The * caller may choose to observe the status of the launched process by calling methods on the * returned object. * * @param stdinInput bytes to be written to process's stdin, or {@link #NO_INPUT} if no bytes * should be written * @return An object that can be used to check if the process terminated and obtain the process * results. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any reason * @throws NullPointerException if stdin is null */ public FutureCommandResult executeAsynchronously(final byte[] stdinInput) throws CommandException { return executeAsynchronously(stdinInput, NO_OBSERVER); } /** *

Executes this command with the given input to stdin, but does * not wait for it to complete. The caller may choose to observe the * status of the launched process by calling methods on the returned * object. This method performs the minimum cleanup after the * process terminates: It closes the input stream, and it ignores * exceptions that result from closing it. The given {@link * KillableObserver} may also terminate the process early while * running.

* *

Note that in this case the {@link KillableObserver} will be assigned * to start observing the process via * {@link KillableObserver#startObserving(Killable)} but will only be * unassigned via {@link KillableObserver#stopObserving(Killable)}, if * {@link FutureCommandResult#get()} is called. If the * {@link KillableObserver} implementation used with this method will * not work correctly without calls to * {@link KillableObserver#stopObserving(Killable)} then a new instance * should be used for each call to this method.

* * @param stdinInput bytes to be written to process's stdin, or * {@link #NO_INPUT} if no bytes should be written * @param observer {@link KillableObserver} that should observe the running * process, or {@link #NO_OBSERVER} if caller does not wish to kill * the process * @return An object that can be used to check if the process terminated and * obtain the process results. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws NullPointerException if stdin is null */ public FutureCommandResult executeAsynchronously(final byte[] stdinInput, final KillableObserver observer) throws CommandException { // supporting "null" here for backwards compatibility final KillableObserver theObserver = observer == null ? NO_OBSERVER : observer; nullCheck(stdinInput, "stdinInput"); return doExecute(new ByteArrayInputSource(stdinInput), theObserver, Consumers.createDiscardingConsumers(), /*killSubprocess=*/false, /*closeOutput=*/false); } /** *

Executes this command with the given input to stdin, but does * not wait for it to complete. The caller may choose to observe the * status of the launched process by calling methods on the returned * object. This method performs the minimum cleanup after the * process terminates: It closes the input stream, and it ignores * exceptions that result from closing it. The caller provides * {@link OutputStream} instances into which the process writes its * stdout/stderr output; these streams are not closed when * the process terminates. The given {@link KillableObserver} may * also terminate the process early while running.

* *

Note that stdout and stderr are written concurrently. If these are * aliased to each other, or if the caller continues to write to these * streams, it is the caller's duty to ensure thread safety. *

* *

Note that in this case the {@link KillableObserver} will be assigned * to start observing the process via * {@link KillableObserver#startObserving(Killable)} but will only be * unassigned via {@link KillableObserver#stopObserving(Killable)}, if * {@link FutureCommandResult#get()} is called. If the * {@link KillableObserver} implementation used with this method will * not work correctly without calls to * {@link KillableObserver#stopObserving(Killable)} then a new instance * should be used for each call to this method.

* * @param stdinInput The input to this process's stdin * @param observer {@link KillableObserver} that should observe the running * process, or {@link #NO_OBSERVER} if caller does not wish to kill * the process * @param stdOut the process will write its standard output into this stream. * E.g., you could pass {@link System#out} as stdOut. * @param stdErr the process will write its standard error into this stream. * E.g., you could pass {@link System#err} as stdErr. * @param killSubprocessOnInterrupt whether or not to kill the created process on interrupt * @param closeOutput whether to close stdout / stderr when the process closes its output streams. * @return An object that can be used to check if the process terminated and * obtain the process results. * @throws ExecFailedException if {@link Runtime#exec(String[])} fails for any * reason * @throws NullPointerException if stdin is null */ public FutureCommandResult executeAsynchronously(final InputStream stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr, final boolean killSubprocessOnInterrupt, final boolean closeOutput) throws CommandException { // supporting "null" here for backwards compatibility final KillableObserver theObserver = observer == null ? NO_OBSERVER : observer; nullCheck(stdinInput, "stdinInput"); return doExecute(new InputStreamInputSource(stdinInput), theObserver, Consumers.createStreamingConsumers(stdOut, stdErr), killSubprocessOnInterrupt, closeOutput); } public FutureCommandResult executeAsynchronously(final InputStream stdinInput, final KillableObserver observer, final OutputStream stdOut, final OutputStream stdErr) throws CommandException { return executeAsynchronously( stdinInput, observer, stdOut, stdErr, /*killSubprocess=*/ false, /*closeOutput=*/ false); } // End of public API ------------------------------------------------------- private void nullCheck(Object argument, String argumentName) { if (argument == null) { String message = argumentName + " argument must not be null."; throw new NullPointerException(message); } } private FutureCommandResult doExecute(final InputSource stdinInput, final KillableObserver observer, final Consumers.OutErrConsumers outErrConsumers, final boolean killSubprocessOnInterrupt, final boolean closeOutputStreams) throws CommandException { logCommand(); final Subprocess process = startProcess(); outErrConsumers.logConsumptionStrategy(); outErrConsumers.registerInputs( process.getInputStream(), process.getErrorStream(), closeOutputStreams); processInput(stdinInput, process); // TODO(bazel-team): if the input stream is unbounded, observers will not get start // notification in a timely manner! final Killable processKillable = observeProcess(process, observer); return new FutureCommandResult() { @Override public CommandResult get() throws AbnormalTerminationException { return waitForProcessToComplete(process, observer, processKillable, outErrConsumers, killSubprocessOnInterrupt); } @Override public boolean isDone() { return process.finished(); } }; } private Subprocess startProcess() throws ExecFailedException { try { return subprocessBuilder.start(); } catch (IOException ioe) { throw new ExecFailedException(this, ioe); } } private static interface InputSource { void copyTo(OutputStream out) throws IOException; boolean isEmpty(); String toLogString(String sourceName); } private static class ByteArrayInputSource implements InputSource { private byte[] bytes; ByteArrayInputSource(byte[] bytes){ this.bytes = bytes; } @Override public void copyTo(OutputStream out) throws IOException { out.write(bytes); out.flush(); } @Override public boolean isEmpty() { return bytes.length == 0; } @Override public String toLogString(String sourceName) { if (isEmpty()) { return "No input to " + sourceName; } else { return "Input to " + sourceName + ": " + LogUtil.toTruncatedString(bytes); } } } private static class InputStreamInputSource implements InputSource { private InputStream inputStream; InputStreamInputSource(InputStream inputStream){ this.inputStream = inputStream; } @Override public void copyTo(OutputStream out) throws IOException { byte[] buf = new byte[4096]; int r; while ((r = inputStream.read(buf)) != -1) { out.write(buf, 0, r); out.flush(); } } @Override public boolean isEmpty() { return false; } @Override public String toLogString(String sourceName) { return "Input to " + sourceName + " is a stream."; } } private static void processInput(InputSource stdinInput, Subprocess process) { if (log.isLoggable(Level.FINER)) { log.finer(stdinInput.toLogString("stdin")); } try { if (stdinInput.isEmpty()) { return; } stdinInput.copyTo(process.getOutputStream()); } catch (IOException ioe) { // Note: this is not an error! Perhaps the command just isn't hungry for // our input and exited with success. Process.waitFor (later) will tell // us. // // (Unlike out/err streams, which are read asynchronously, the input stream is written // synchronously, in its entirety, before processInput returns. If the input is // infinite, and is passed through e.g. "cat" subprocess and back into the // ByteArrayOutputStream, that will eventually run out of memory, causing the output stream // to be closed, "cat" to terminate with SIGPIPE, and processInput to receive an IOException. } finally { // if this statement is ever deleted, the process's outputStream // must be closed elsewhere -- it is not closed automatically Command.silentClose(process.getOutputStream()); } } private static Killable observeProcess(Subprocess process, final KillableObserver observer) { final Killable processKillable = new ProcessKillable(process); observer.startObserving(processKillable); return processKillable; } private CommandResult waitForProcessToComplete( final Subprocess process, final KillableObserver observer, final Killable processKillable, final Consumers.OutErrConsumers outErr, final boolean killSubprocessOnInterrupt) throws AbnormalTerminationException { log.finer("Waiting for process..."); TerminationStatus status = waitForProcess(process, killSubprocessOnInterrupt); observer.stopObserving(processKillable); log.finer(status.toString()); try { if (Thread.currentThread().isInterrupted()) { outErr.cancel(); } else { outErr.waitForCompletion(); } } catch (IOException ioe) { CommandResult noOutputResult = new CommandResult(CommandResult.EMPTY_OUTPUT, CommandResult.EMPTY_OUTPUT, status); if (status.success()) { // If command was otherwise successful, throw an exception about this throw new AbnormalTerminationException(this, noOutputResult, ioe); } else { // Otherwise, throw the more important exception -- command // was not successful String message = status + "; also encountered an error while attempting to retrieve output"; throw status.exited() ? new BadExitStatusException(this, noOutputResult, message, ioe) : new AbnormalTerminationException(this, noOutputResult, message, ioe); } } finally { // #close() must be called after the #stopObserving() so that a badly-timed timeout does not // try to destroy a process that is already closed, and after outErr is completed, // so that it has a chance to read the entire output is captured. process.close(); } CommandResult result = new CommandResult(outErr.getAccumulatedOut(), outErr.getAccumulatedErr(), status); result.logThis(); if (status.success()) { return result; } else if (status.exited()) { throw new BadExitStatusException(this, result, status.toString()); } else { throw new AbnormalTerminationException(this, result, status.toString()); } } private static TerminationStatus waitForProcess(Subprocess process, boolean killSubprocessOnInterrupt) { boolean wasInterrupted = false; try { while (true) { try { process.waitFor(); return new TerminationStatus(process.exitValue(), process.timedout()); } catch (InterruptedException ie) { wasInterrupted = true; if (killSubprocessOnInterrupt) { process.destroy(); } } } } finally { // Read this for detailed explanation: http://www.ibm.com/developerworks/library/j-jtp05236/ if (wasInterrupted) { Thread.currentThread().interrupt(); // preserve interrupted status } } } private void logCommand() { if (!log.isLoggable(Level.FINE)) { return; } log.fine(toDebugString()); } /** * A string representation of this command object which includes * the arguments, the environment, and the working directory. Avoid * relying on the specifics of this format. Note that the size * of the result string will reflect the size of the command. */ public String toDebugString() { StringBuilder message = new StringBuilder(128); message.append("Executing (without brackets):"); for (String arg : subprocessBuilder.getArgv()) { message.append(" ["); message.append(arg); message.append(']'); } message.append("; environment: "); message.append(subprocessBuilder.getEnv()); message.append("; working dir: "); File workingDirectory = subprocessBuilder.getWorkingDirectory(); message.append(workingDirectory == null ? "(current)" : workingDirectory.toString()); return message.toString(); } /** * Close the out stream and log a warning if anything happens. */ private static void silentClose(final OutputStream out) { try { out.close(); } catch (IOException ioe) { String message = "Unexpected exception while closing output stream"; log.log(Level.WARNING, message, ioe); } } }