File: Exec.cs
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Project: ..\..\..\src\Tasks\Microsoft.Build.Tasks.csproj (Microsoft.Build.Tasks.Core)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using Microsoft.Build.Framework;
using Microsoft.Build.Shared;
using Microsoft.Build.Shared.FileSystem;
using Microsoft.Build.Utilities;
 
#nullable disable
 
namespace Microsoft.Build.Tasks
{
    /// <summary>
    /// This class defines an "Exec" MSBuild task, which simply invokes the specified process with the specified arguments, waits
    /// for it to complete, and then returns True if the process completed successfully, and False if an error occurred.
    /// </summary>
    // UNDONE: ToolTask has a "UseCommandProcessor" flag that duplicates much of the code in this class. Remove the duplication.
    public class Exec : ToolTaskExtension
    {
        #region Constructors
 
        /// <summary>
        /// Default constructor.
        /// </summary>
        public Exec()
        {
            Command = string.Empty;
 
            // Console-based output uses the current system OEM code page by default. Note that we should not use Console.OutputEncoding
            // here since processes we run don't really have much to do with our console window (and also Console.OutputEncoding
            // doesn't return the OEM code page if the running application that hosts MSBuild is not a console application).
            // If the cmd file contains non-ANSI characters encoding may change.
            _standardOutputEncoding = EncodingUtilities.CurrentSystemOemEncoding;
            _standardErrorEncoding = EncodingUtilities.CurrentSystemOemEncoding;
        }
 
        #endregion
 
        #region Fields
 
        // Are the encodings for StdErr and StdOut streams valid
        private bool _encodingParametersValid = true;
        private string _workingDirectory;
        private ITaskItem[] _outputs;
        internal bool workingDirectoryIsUNC; // internal for unit testing
        private string _batchFile;
        private string _customErrorRegex;
        private string _customWarningRegex;
        private readonly List<ITaskItem> _nonEmptyOutput = new List<ITaskItem>();
        private Encoding _standardErrorEncoding;
        private Encoding _standardOutputEncoding;
        private string _command;
 
        // '^' before _any_ character escapes that character, don't escape it.
        private static readonly char[] _charactersToEscape = { '(', ')', '=', ';', '!', ',', '&', ' ' };
 
        #endregion
 
        #region Properties
 
        [Required]
        public string Command
        {
            get => _command;
            set
            {
                _command = value;
                if (NativeMethodsShared.IsUnixLike)
                {
                    _command = _command.Replace("\r\n", "\n");
                }
            }
        }
 
        public string WorkingDirectory { get; set; }
 
        public bool IgnoreExitCode { get; set; }
 
        /// <summary>
        /// Enable the pipe of the standard out to an item (StandardOutput).
        /// </summary>
        /// <Remarks>
        /// Even thought this is called a pipe, it is in fact a Tee.  Use StandardOutputImportance to adjust the visibility of the stdout.
        /// </Remarks>
        public bool ConsoleToMSBuild { get; set; }
 
        /// <summary>
        /// Users can supply a regular expression that we should
        /// use to spot error lines in the tool output. This is
        /// useful for tools that produce unusually formatted output
        /// </summary>
        public string CustomErrorRegularExpression
        {
            get => _customErrorRegex;
            set => _customErrorRegex = value;
        }
 
        /// <summary>
        /// Users can supply a regular expression that we should
        /// use to spot warning lines in the tool output. This is
        /// useful for tools that produce unusually formatted output
        /// </summary>
        public string CustomWarningRegularExpression
        {
            get => _customWarningRegex;
            set => _customWarningRegex = value;
        }
 
        /// <summary>
        /// Whether to use pick out lines in the output that match
        /// the standard error/warning format, and log them as errors/warnings.
        /// Defaults to false.
        /// </summary>
        public bool IgnoreStandardErrorWarningFormat { get; set; }
 
        /// <summary>
        /// Property specifying the encoding of the captured task standard output stream
        /// </summary>
        protected override Encoding StandardOutputEncoding => _standardOutputEncoding;
 
        /// <summary>
        /// Property specifying the encoding of the captured task standard error stream
        /// </summary>
        protected override Encoding StandardErrorEncoding => _standardErrorEncoding;
 
        /// <summary>
        /// Project visible property specifying the encoding of the captured task standard output stream
        /// </summary>
        [Output]
        public string StdOutEncoding
        {
            get => StandardOutputEncoding.EncodingName;
            set
            {
                try
                {
                    _standardOutputEncoding = Encoding.GetEncoding(value);
                }
                catch (ArgumentException)
                {
                    Log.LogErrorWithCodeFromResources("General.InvalidValue", "StdOutEncoding", "Exec");
                    _encodingParametersValid = false;
                }
            }
        }
 
        /// <summary>
        /// Project visible property specifying the encoding of the captured task standard error stream
        /// </summary>
        [Output]
        public string StdErrEncoding
        {
            get => StandardErrorEncoding.EncodingName;
            set
            {
                try
                {
                    _standardErrorEncoding = Encoding.GetEncoding(value);
                }
                catch (ArgumentException)
                {
                    Log.LogErrorWithCodeFromResources("General.InvalidValue", "StdErrEncoding", "Exec");
                    _encodingParametersValid = false;
                }
            }
        }
 
        [Output]
        public ITaskItem[] Outputs
        {
            get => _outputs ?? Array.Empty<ITaskItem>();
            set => _outputs = value;
        }
 
        /// <summary>
        /// Returns the output as an Item.  Whitespace are trimmed.
        /// ConsoleOutput is enabled when ConsoleToMSBuild is true.  This avoids holding lines in memory
        /// if they aren't used.  ConsoleOutput is a combination of stdout and stderr.
        /// </summary>
        [Output]
        public ITaskItem[] ConsoleOutput => !ConsoleToMSBuild ? Array.Empty<ITaskItem>() : _nonEmptyOutput.ToArray();
 
        #endregion
 
        #region Methods
        /// <summary>
        /// Write out a temporary batch file with the user-specified command in it.
        /// </summary>
        private void CreateTemporaryBatchFile()
        {
            var encoding = EncodingUtilities.BatchFileEncoding(Command + WorkingDirectory, UseUtf8Encoding);
 
            // Temporary file with the extension .Exec.bat
            _batchFile = FileUtilities.GetTemporaryFileName(".exec.cmd");
 
            // UNICODE Batch files are not allowed as of WinXP. We can't use normal ANSI code pages either,
            // since console-related apps use OEM code pages "for historical reasons". Sigh.
            // We need to get the current OEM code page which will be the same language as the current ANSI code page,
            // just the OEM version.
            // See http://www.microsoft.com/globaldev/getWR/steps/wrg_codepage.mspx for a discussion of ANSI vs OEM
            // Note: 8/12/15 - Switched to use UTF8 on OS newer than 6.1 (Windows 7)
            // Note: 1/12/16 - Only use UTF8 when we detect we need to or the user specifies 'Always'
            using (StreamWriter sw = FileUtilities.OpenWrite(_batchFile, false, encoding))
            {
                if (!NativeMethodsShared.IsUnixLike)
                {
                    // In some wierd setups, users may have set an env var actually called "errorlevel"
                    // this would cause our "exit %errorlevel%" to return false.
                    // This is because the actual errorlevel value is not an environment variable, but some commands,
                    // such as "exit %errorlevel%" will use the environment variable with that name if it exists, instead
                    // of the actual errorlevel value. So we must temporarily reset errorlevel locally first.
                    sw.WriteLine("setlocal");
                    // One more wrinkle.
                    // "set foo=" has odd behavior: it sets errorlevel to 1 if there was no environment variable named
                    // "foo" defined.
                    // This has the effect of making "set errorlevel=" set an errorlevel of 1 if an environment
                    // variable named "errorlevel" didn't already exist!
                    // To avoid this problem, set errorlevel locally to a dummy value first.
                    sw.WriteLine("set errorlevel=dummy");
                    sw.WriteLine("set errorlevel=");
 
                    // We may need to change the code page and console encoding.
                    if (encoding.CodePage != EncodingUtilities.CurrentSystemOemEncoding.CodePage)
                    {
                        // Output to nul so we don't change output and logs.
                        sw.WriteLine($@"%SystemRoot%\System32\chcp.com {encoding.CodePage}>nul");
 
                        // Ensure that the console encoding is correct.
                        _standardOutputEncoding = encoding;
                        _standardErrorEncoding = encoding;
                    }
 
                    // if the working directory is a UNC path, bracket the exec command with pushd and popd, because pushd
                    // automatically maps the network path to a drive letter, and then popd disconnects it.
                    // This is required because Cmd.exe does not support UNC names as the current directory:
                    // https://support.microsoft.com/en-us/kb/156276
                    if (workingDirectoryIsUNC)
                    {
                        sw.WriteLine("pushd " + _workingDirectory);
                    }
                }
                else
                {
                    // Use sh rather than bash, as not all 'nix systems necessarily have Bash installed
                    sw.WriteLine("#!/bin/sh");
                }
 
                sw.WriteLine(Command);
 
                if (!NativeMethodsShared.IsUnixLike)
                {
                    if (workingDirectoryIsUNC)
                    {
                        sw.WriteLine("popd");
                    }
 
                    // NOTES:
                    // 1) there's a bug in the Process class where the exit code is not returned properly i.e. if the command
                    //    fails with exit code 9009, Process.ExitCode returns 1 -- the statement below forces it to return the
                    //    correct exit code
                    // 2) also because of another (or perhaps the same) bug in the Process class, when we use pushd/popd for a
                    //    UNC path, even if the command fails, the exit code comes back as 0 (seemingly reflecting the success
                    //    of popd) -- the statement below fixes that too
                    // 3) the above described behaviour is most likely bugs in the Process class because batch files in a
                    //    console window do not hide or change the exit code a.k.a. errorlevel, esp. since the popd command is
                    //    a no-fail command, and it never changes the previous errorlevel
                    sw.WriteLine("exit %errorlevel%");
                }
            }
        }
        #endregion
 
        #region Overridden methods
 
        /// <summary>
        /// Executes cmd.exe and waits for it to complete
        /// </summary>
        /// <remarks>
        /// Overridden to clean up the batch file afterwards.
        /// </remarks>
        /// <returns>Upon completion of the process, returns True if successful, False if not.</returns>
        protected override int ExecuteTool(string pathToTool, string responseFileCommands, string commandLineCommands)
        {
            try
            {
                return base.ExecuteTool(pathToTool, responseFileCommands, commandLineCommands);
            }
            finally
            {
                DeleteTempFile(_batchFile);
            }
        }
 
        /// <summary>
        /// Allows tool to handle the return code.
        /// This method will only be called with non-zero exitCode set to true.
        /// </summary>
        /// <remarks>
        /// Overridden to make sure we display the command we put in the batch file, not the cmd.exe command
        /// used to run the batch file.
        /// </remarks>
        protected override bool HandleTaskExecutionErrors()
        {
            if (IgnoreExitCode)
            {
                // Don't log when EchoOff and IgnoreExitCode.
                if (!EchoOff)
                {
                    Log.LogMessageFromResources(MessageImportance.Normal, "Exec.CommandFailedNoErrorCode", Command, ExitCode);
                }
                return true;
            }
 
            // Don't emit expanded form of Command when EchoOff is set.
            string commandForLog = EchoOff ? "..." : Command;
            if (ExitCode == NativeMethods.SE_ERR_ACCESSDENIED)
            {
                Log.LogErrorWithCodeFromResources("Exec.CommandFailedAccessDenied", commandForLog, ExitCode);
            }
            else
            {
                Log.LogErrorWithCodeFromResources("Exec.CommandFailed", commandForLog, ExitCode);
            }
            return false;
        }
 
        /// <summary>
        /// Logs the tool name and the path from where it is being run.
        /// </summary>
        /// <remarks>
        /// Overridden to avoid logging the path to "cmd.exe", which is not interesting.
        /// </remarks>
        protected override void LogPathToTool(string toolName, string pathToTool)
        {
            // Do nothing
        }
 
        /// <summary>
        /// Logs the command to be executed.
        /// </summary>
        /// <remarks>
        /// Overridden to log the batch file command instead of the cmd.exe command.
        /// </remarks>
        /// <param name="message"></param>
        protected override void LogToolCommand(string message)
        {
            // Dont print the command line if Echo is Off.
            if (!EchoOff)
            {
                base.LogToolCommand(Command);
            }
        }
 
        /// <summary>
        /// Calls a method on the TaskLoggingHelper to parse a single line of text to
        /// see if there are any errors or warnings in canonical format.
        /// </summary>
        /// <remarks>
        /// Overridden to handle any custom regular expressions supplied.
        /// </remarks>
        protected override void LogEventsFromTextOutput(string singleLine, MessageImportance messageImportance)
        {
            if (OutputMatchesRegex(singleLine, ref _customErrorRegex))
            {
                Log.LogError(singleLine);
            }
            else if (OutputMatchesRegex(singleLine, ref _customWarningRegex))
            {
                Log.LogWarning(singleLine);
            }
            else if (IgnoreStandardErrorWarningFormat)
            {
                // Not detecting regular format errors and warnings, and it didn't
                // match any regexes either -- log as a regular message
                Log.LogMessage(messageImportance, singleLine, null);
            }
            else
            {
                // This is the normal code path: match standard format errors and warnings
                Log.LogMessageFromText(singleLine, messageImportance);
            }
 
            if (ConsoleToMSBuild)
            {
                string trimmedTextLine = ChangeWaves.AreFeaturesEnabled(ChangeWaves.Wave17_10) ?
                    singleLine.TrimEnd() :
                    singleLine.Trim();
 
                if (trimmedTextLine.Length > 0)
                {
                    // The lines read may be unescaped, so we need to escape them
                    // before passing them to the TaskItem.
                    _nonEmptyOutput.Add(new TaskItem(EscapingUtilities.Escape(trimmedTextLine)));
                }
            }
        }
 
        /// <summary>
        /// Returns true if the string is matched by the regular expression.
        /// If the regular expression is invalid, logs an error, then clears it out to
        /// prevent more errors.
        /// </summary>
        private bool OutputMatchesRegex(string singleLine, ref string regularExpression)
        {
            if (regularExpression == null)
            {
                return false;
            }
 
            bool match = false;
 
            try
            {
                match = Regex.IsMatch(singleLine, regularExpression);
            }
            catch (ArgumentException ex)
            {
                Log.LogErrorWithCodeFromResources("Exec.InvalidRegex", regularExpression, ex.Message);
                // Clear out the regex so there won't be any more errors; let the tool continue,
                // then it will fail because of the error we just logged
                regularExpression = null;
            }
 
            return match;
        }
 
        /// <summary>
        /// Validate the task arguments, log any warnings/errors
        /// </summary>
        /// <returns>true if arguments are corrent enough to continue processing, false otherwise</returns>
        protected override bool ValidateParameters()
        {
            // If either of the encoding parameters passed to the task were
            // invalid, then we should report that fact back to tooltask
            if (!_encodingParametersValid)
            {
                return false;
            }
 
            // Make sure that at least the Command property was set
            if (Command.Trim().Length == 0)
            {
                Log.LogErrorWithCodeFromResources("Exec.MissingCommandError");
                return false;
            }
 
            // determine what the working directory for the exec command is going to be -- if the user specified a working
            // directory use that, otherwise it's the current directory
            _workingDirectory = !string.IsNullOrEmpty(WorkingDirectory)
                ? WorkingDirectory
                : Directory.GetCurrentDirectory();
 
            // check if the working directory we're going to use for the exec command is a UNC path
            workingDirectoryIsUNC = FileUtilitiesRegex.StartsWithUncPattern(_workingDirectory);
 
            // if the working directory is a UNC path, and all drive letters are mapped, bail out, because the pushd command
            // will not be able to auto-map to the UNC path
            if (workingDirectoryIsUNC && NativeMethods.AllDrivesMapped())
            {
                Log.LogErrorWithCodeFromResources("Exec.AllDriveLettersMappedError", _workingDirectory);
                return false;
            }
 
            return true;
        }
 
        /// <summary>
        /// Accessor for ValidateParameters purely for unit-test use
        /// </summary>
        /// <returns></returns>
        internal bool ValidateParametersAccessor()
        {
            return ValidateParameters();
        }
 
        /// <summary>
        /// Determining the path to cmd.exe
        /// </summary>
        /// <returns>path to cmd.exe</returns>
        protected override string GenerateFullPathToTool()
        {
            return CommandProcessorPath.Value;
        }
 
        private static readonly Lazy<string> CommandProcessorPath = new Lazy<string>(() =>
        {
            // Get the fully qualified path to cmd.exe
            if (NativeMethodsShared.IsWindows)
            {
                var systemCmd = ToolLocationHelper.GetPathToSystemFile("cmd.exe");
 
#if WORKAROUND_COREFX_19110
                // Work around https://github.com/dotnet/msbuild/issues/2273 and
                // https://github.com/dotnet/corefx/issues/19110, which result in
                // a bad path being returned above on Nano Server SKUs of Windows.
                if (!FileSystems.Default.FileExists(systemCmd))
                {
                    return Environment.GetEnvironmentVariable("ComSpec");
                }
#endif
 
                return systemCmd;
            }
            else
            {
                return "sh";
            }
        });
 
        /// <summary>
        /// Gets the working directory to use for the process. Should return null if ToolTask should use the
        /// current directory.
        /// May throw an IOException if the directory to be used is somehow invalid.
        /// </summary>
        /// <returns>working directory</returns>
        protected override string GetWorkingDirectory()
        {
            // If the working directory is UNC, we're going to use "pushd" in the batch file to set it.
            // If it's invalid, pushd won't fail: it will just go ahead and use the system folder.
            // So verify it's valid here.
            if (!FileSystems.Default.DirectoryExists(_workingDirectory))
            {
                throw new DirectoryNotFoundException(ResourceUtilities.FormatResourceStringStripCodeAndKeyword("Exec.InvalidWorkingDirectory", _workingDirectory));
            }
 
            if (workingDirectoryIsUNC)
            {
                // if the working directory for the exec command is UNC, set the process working directory to the system path
                // so that it doesn't display this silly error message:
                //      '\\<server>\<share>'
                //      CMD.EXE was started with the above path as the current directory.
                //      UNC paths are not supported.  Defaulting to Windows directory.
                return ToolLocationHelper.PathToSystem;
            }
            else
            {
                return _workingDirectory;
            }
        }
 
        /// <summary>
        /// Accessor for GetWorkingDirectory purely for unit-test use
        /// </summary>
        /// <returns></returns>
        internal string GetWorkingDirectoryAccessor()
        {
            return GetWorkingDirectory();
        }
 
        /// <summary>
        /// Adds the arguments for cmd.exe
        /// </summary>
        /// <param name="commandLine">command line builder class to add arguments to</param>
        protected internal override void AddCommandLineCommands(CommandLineBuilderExtension commandLine)
        {
            // Create the batch file now,
            // so we have the file name for the cmd.exe command line
            CreateTemporaryBatchFile();
 
            string batchFileForCommandLine = _batchFile;
 
            // Unix consoles cannot have their encodings changed in place (like chcp on windows).
            // Instead, unix scripts receive encoding information via environment variables before invocation.
            // In consequence, encoding setup has to be performed outside the script, not inside it.
            if (NativeMethodsShared.IsUnixLike)
            {
                commandLine.AppendSwitch("-c");
                commandLine.AppendTextUnquoted(" \"");
                bool setLocale = !ChangeWaves.AreFeaturesEnabled(ChangeWaves.Wave17_10);
                if (setLocale)
                {
                    commandLine.AppendTextUnquoted("export LANG=en_US.UTF-8; export LC_ALL=en_US.UTF-8; ");
                }
                commandLine.AppendTextUnquoted(". ");
                commandLine.AppendFileNameIfNotNull(batchFileForCommandLine);
                commandLine.AppendTextUnquoted("\"");
            }
            else
            {
                if (NativeMethodsShared.IsWindows)
                {
                    commandLine.AppendSwitch("/Q"); // echo off
                    if (!Traits.Instance.EscapeHatches.UseAutoRunWhenLaunchingProcessUnderCmd)
                    {
                        commandLine.AppendSwitch("/D"); // do not load AutoRun configuration from the registry (perf)
                    }
                    commandLine.AppendSwitch("/C"); // run then terminate
 
                    StringBuilder fileName = null;
 
                    // Escape special characters that need to be escaped.
                    for (int i = 0; i < batchFileForCommandLine.Length; i++)
                    {
                        char c = batchFileForCommandLine[i];
 
                        if (ShouldEscapeCharacter(c) && (i == 0 || batchFileForCommandLine[i - 1] != '^'))
                        {
                            // Avoid allocating a new string until we know we have something to escape.
                            if (fileName == null)
                            {
                                fileName = StringBuilderCache.Acquire(batchFileForCommandLine.Length);
                                fileName.Append(batchFileForCommandLine, 0, i);
                            }
 
                            fileName.Append('^');
                        }
 
                        fileName?.Append(c);
                    }
 
                    if (fileName != null)
                    {
                        batchFileForCommandLine = StringBuilderCache.GetStringAndRelease(fileName);
                    }
                }
 
                commandLine.AppendFileNameIfNotNull(batchFileForCommandLine);
            }
        }
 
        private bool ShouldEscapeCharacter(char c)
        {
            for (int i = 0; i < _charactersToEscape.Length; i++)
            {
                if (c == _charactersToEscape[i])
                {
                    return true;
                }
            }
 
            return false;
        }
 
        #endregion
 
        #region Overridden properties
 
        /// <summary>
        /// The name of the tool to execute
        /// </summary>
        protected override string ToolName => NativeMethodsShared.IsWindows ? "cmd.exe" : "sh";
 
        /// <summary>
        /// Importance with which to log ordinary messages in the
        /// standard error stream.
        /// </summary>
        protected override MessageImportance StandardErrorLoggingImportance => MessageImportance.High;
 
        /// <summary>
        /// Importance with which to log ordinary messages in the
        /// standard out stream.
        /// </summary>
        /// <remarks>
        /// Overridden to increase from the default "Low" up to "High".
        /// </remarks>
        protected override MessageImportance StandardOutputLoggingImportance => MessageImportance.High;
 
        #endregion
    }
}