Configuration.cs

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using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
 
using Microsoft.Extensions.Logging;
 
using Tgstation.Server.Api.Models;
using Tgstation.Server.Api.Models.Response;
using Tgstation.Server.Common.Extensions;
using Tgstation.Server.Host.Components.Events;
using Tgstation.Server.Host.Configuration;
using Tgstation.Server.Host.Extensions;
using Tgstation.Server.Host.IO;
using Tgstation.Server.Host.Jobs;
using Tgstation.Server.Host.Security;
using Tgstation.Server.Host.System;
using Tgstation.Server.Host.Transfer;
using Tgstation.Server.Host.Utils;
 
namespace Tgstation.Server.Host.Components.StaticFiles
{
    sealed class Configuration : IConfiguration
    {
        const string CodeModificationsSubdirectory = "CodeModifications";
 
        const string EventScriptsSubdirectory = "EventScripts";
 
        const string GameStaticFilesSubdirectory = "GameStaticFiles";
 
        const string StaticIgnoreFile = ".tgsignore";
 
        const string CodeModificationsHeadFile = "HeadInclude.dm";
 
        const string CodeModificationsTailFile = "TailInclude.dm";
 
        static readonly string DefaultHeadInclude = @$"// TGS AUTO GENERATED HeadInclude.dm{Environment.NewLine}// This file will be included BEFORE all code in your .dme IF a replacement .dme does not exist in this directory{Environment.NewLine}// Please note that changes need to be made available if you are hosting an AGPL licensed codebase{Environment.NewLine}// The presence file in its default state does not constitute a code change that needs to be published by licensing standards{Environment.NewLine}";
 
        static readonly string DefaultTailInclude = @$"// TGS AUTO GENERATED TailInclude.dm{Environment.NewLine}// This file will be included AFTER all code in your .dme IF a replacement .dme does not exist in this directory{Environment.NewLine}// Please note that changes need to be made available if you are hosting an AGPL licensed codebase{Environment.NewLine}// The presence file in its default state does not constitute a code change that needs to be published by licensing standards{Environment.NewLine}";
 
        public static IReadOnlyDictionary<EventType, string[]> EventTypeScriptFileNameMap { get; } = new Dictionary<EventType, string[]>(
            Enum.GetValues(typeof(EventType))
                .Cast<EventType>()
                .Select(
                    eventType => new KeyValuePair<EventType, string[]>(
                        eventType,
                        typeof(EventType)
                            .GetField(eventType.ToString())!
                            .GetCustomAttributes(false)
                            .OfType<EventScriptAttribute>()
                            .First()
                            .ScriptNames)));
 
        readonly IIOManager ioManager;
 
        readonly ISynchronousIOManager synchronousIOManager;
 
        readonly IFilesystemLinkFactory linkFactory;
 
        readonly IProcessExecutor processExecutor;
 
        readonly IPostWriteHandler postWriteHandler;
 
        readonly IPlatformIdentifier platformIdentifier;
 
        readonly IFileTransferTicketProvider fileTransferService;
 
        readonly ILogger<Configuration> logger;
 
        readonly GeneralConfiguration generalConfiguration;
 
        readonly SessionConfiguration sessionConfiguration;
 
        readonly SemaphoreSlim semaphore;
 
        readonly CancellationTokenSource disposeCts;
 
        Task uploadTasks;
 
        public Configuration(
            IIOManager ioManager,
            ISynchronousIOManager synchronousIOManager,
            IFilesystemLinkFactory linkFactory,
            IProcessExecutor processExecutor,
            IPostWriteHandler postWriteHandler,
            IPlatformIdentifier platformIdentifier,
            IFileTransferTicketProvider fileTransferService,
            ILogger<Configuration> logger,
            GeneralConfiguration generalConfiguration,
            SessionConfiguration sessionConfiguration)
        {
            this.ioManager = ioManager ?? throw new ArgumentNullException(nameof(ioManager));
            this.synchronousIOManager = synchronousIOManager ?? throw new ArgumentNullException(nameof(synchronousIOManager));
            this.linkFactory = linkFactory ?? throw new ArgumentNullException(nameof(linkFactory));
            this.processExecutor = processExecutor ?? throw new ArgumentNullException(nameof(processExecutor));
            this.postWriteHandler = postWriteHandler ?? throw new ArgumentNullException(nameof(postWriteHandler));
            this.platformIdentifier = platformIdentifier ?? throw new ArgumentNullException(nameof(platformIdentifier));
            this.fileTransferService = fileTransferService ?? throw new ArgumentNullException(nameof(fileTransferService));
            this.logger = logger ?? throw new ArgumentNullException(nameof(logger));
            this.generalConfiguration = generalConfiguration ?? throw new ArgumentNullException(nameof(generalConfiguration));
            this.sessionConfiguration = sessionConfiguration ?? throw new ArgumentNullException(nameof(sessionConfiguration));
 
            semaphore = new SemaphoreSlim(1);
            disposeCts = new CancellationTokenSource();
            uploadTasks = Task.CompletedTask;
        }
 
        public void Dispose()
        {
            semaphore.Dispose();
            disposeCts.Cancel();
            disposeCts.Dispose();
        }
 
        public async ValueTask<ServerSideModifications?> CopyDMFilesTo(string dmeFile, string destination, CancellationToken cancellationToken)
        {
            using (await SemaphoreSlimContext.Lock(semaphore, cancellationToken))
            {
                var ensureDirectoriesTask = EnsureDirectories(cancellationToken);
 
                // just assume no other fs race conditions here
                var dmeExistsTask = ioManager.FileExists(ioManager.ConcatPath(CodeModificationsSubdirectory, dmeFile), cancellationToken);
                var headFileExistsTask = ioManager.FileExists(ioManager.ConcatPath(CodeModificationsSubdirectory, CodeModificationsHeadFile), cancellationToken);
                var tailFileExistsTask = ioManager.FileExists(ioManager.ConcatPath(CodeModificationsSubdirectory, CodeModificationsTailFile), cancellationToken);
 
                await ensureDirectoriesTask;
                var copyTask = ioManager.CopyDirectory(
                    null,
                    null,
                    CodeModificationsSubdirectory,
                    destination,
                    generalConfiguration.GetCopyDirectoryTaskThrottle(),
                    cancellationToken);
 
                await Task.WhenAll(dmeExistsTask, headFileExistsTask, tailFileExistsTask, copyTask.AsTask());
 
                if (!dmeExistsTask.Result && !headFileExistsTask.Result && !tailFileExistsTask.Result)
                    return null;
 
                if (dmeExistsTask.Result)
                    return new ServerSideModifications(null, null, true);
 
                if (!headFileExistsTask.Result && !tailFileExistsTask.Result)
                    return null;
 
                static string IncludeLine(string filePath) => String.Format(CultureInfo.InvariantCulture, "#include \"{0}\"", filePath);
 
                return new ServerSideModifications(
                    headFileExistsTask.Result
                        ? IncludeLine(CodeModificationsHeadFile)
                        : null,
                    tailFileExistsTask.Result
                        ? IncludeLine(CodeModificationsTailFile)
                        : null,
                    false);
            }
        }
 
        public async ValueTask<IOrderedQueryable<ConfigurationFileResponse>?> ListDirectory(string? configurationRelativePath, ISystemIdentity? systemIdentity, CancellationToken cancellationToken)
        {
            await EnsureDirectories(cancellationToken);
            var path = ValidateConfigRelativePath(configurationRelativePath);
 
            configurationRelativePath ??= "/";
 
            var result = new List<ConfigurationFileResponse>();
 
            void ListImpl()
            {
                var enumerator = synchronousIOManager.GetDirectories(path, cancellationToken);
                result.AddRange(enumerator.Select(x => new ConfigurationFileResponse
                {
                    IsDirectory = true,
                    Path = ioManager.ConcatPath(configurationRelativePath, x),
                }));
 
                enumerator = synchronousIOManager.GetFiles(path, cancellationToken);
                result.AddRange(enumerator.Select(x => new ConfigurationFileResponse
                {
                    IsDirectory = false,
                    Path = ioManager.ConcatPath(configurationRelativePath, x),
                }));
            }
 
            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
            {
                if (!locked)
                {
                    logger.LogDebug("Contention when attempting to enumerate directory!");
                    return null;
                }
 
                if (systemIdentity == null)
                    ListImpl();
                else
                    await systemIdentity.RunImpersonated(ListImpl, cancellationToken);
            }
 
            return result
                .AsQueryable()
                .OrderBy(configFile => !configFile.IsDirectory)
                .ThenBy(configFile => configFile.Path);
        }
 
        public async ValueTask<ConfigurationFileResponse?> Read(string configurationRelativePath, ISystemIdentity? systemIdentity, CancellationToken cancellationToken)
        {
            await EnsureDirectories(cancellationToken);
            var path = ValidateConfigRelativePath(configurationRelativePath);
 
            ConfigurationFileResponse? result = null;
 
            void ReadImpl()
            {
                try
                {
                    string GetFileSha()
                    {
                        var content = synchronousIOManager.ReadFile(path);
                        return String.Join(String.Empty, SHA1.HashData(content).Select(b => b.ToString("x2", CultureInfo.InvariantCulture)));
                    }
 
                    var originalSha = GetFileSha();
 
                    var disposeToken = disposeCts.Token;
                    var fileTicket = fileTransferService.CreateDownload(
                        new FileDownloadProvider(
                            () =>
                            {
                                if (disposeToken.IsCancellationRequested)
                                    return ErrorCode.InstanceOffline;
 
                                var newSha = GetFileSha();
                                if (newSha != originalSha)
                                    return ErrorCode.ConfigurationFileUpdated;
 
                                return null;
                            },
                            async cancellationToken =>
                            {
                                FileStream? result = null;
                                void GetFileStream()
                                {
                                    result = ioManager.GetFileStream(path, false);
                                }
 
                                if (systemIdentity == null)
                                    await Task.Factory.StartNew(GetFileStream, cancellationToken, DefaultIOManager.BlockingTaskCreationOptions, TaskScheduler.Current);
                                else
                                    await systemIdentity.RunImpersonated(GetFileStream, cancellationToken);
 
                                return result!;
                            },
                            path,
                            false));
 
                    result = new ConfigurationFileResponse
                    {
                        FileTicket = fileTicket.FileTicket,
                        IsDirectory = false,
                        LastReadHash = originalSha,
                        AccessDenied = false,
                        Path = configurationRelativePath,
                    };
                }
                catch (UnauthorizedAccessException)
                {
                    // this happens on windows, dunno about linux
                    bool isDirectory;
                    try
                    {
                        isDirectory = synchronousIOManager.IsDirectory(path);
                    }
                    catch (Exception ex)
                    {
                        logger.LogDebug(ex, "IsDirectory exception!");
                        isDirectory = false;
                    }
 
                    result = new ConfigurationFileResponse
                    {
                        Path = configurationRelativePath,
                    };
                    if (!isDirectory)
                        result.AccessDenied = true;
 
                    result.IsDirectory = isDirectory;
                }
            }
 
            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
            {
                if (!locked)
                {
                    logger.LogDebug("Contention when attempting to read file!");
                    return null;
                }
 
                if (systemIdentity == null)
                    await Task.Factory.StartNew(ReadImpl, cancellationToken, DefaultIOManager.BlockingTaskCreationOptions, TaskScheduler.Current);
                else
                    await systemIdentity.RunImpersonated(ReadImpl, cancellationToken);
            }
 
            return result;
        }
 
        public async ValueTask SymlinkStaticFilesTo(string destination, CancellationToken cancellationToken)
        {
            List<string> ignoreFiles;
 
            async ValueTask SymlinkBase(bool files)
            {
                Task<IReadOnlyList<string>> task;
                if (files)
                    task = ioManager.GetFiles(GameStaticFilesSubdirectory, cancellationToken);
                else
                    task = ioManager.GetDirectories(GameStaticFilesSubdirectory, cancellationToken);
                var entries = await task;
 
                await ValueTaskExtensions.WhenAll(entries.Select<string, ValueTask>(async file =>
                {
                    var fileName = ioManager.GetFileName(file);
 
                    // need to normalize
                    var fileComparison = platformIdentifier.IsWindows
                        ? StringComparison.OrdinalIgnoreCase
                        : StringComparison.Ordinal;
                    var ignored = ignoreFiles.Any(y => fileName.Equals(y, fileComparison));
                    if (ignored)
                    {
                        logger.LogTrace("Ignoring static file {fileName}...", fileName);
                        return;
                    }
 
                    var destPath = ioManager.ConcatPath(destination, fileName);
                    logger.LogTrace("Symlinking {filePath} to {destPath}...", file, destPath);
                    var fileExistsTask = ioManager.FileExists(destPath, cancellationToken);
                    if (await ioManager.DirectoryExists(destPath, cancellationToken))
                        await ioManager.DeleteDirectory(destPath, cancellationToken);
                    var fileExists = await fileExistsTask;
                    if (fileExists)
                        await ioManager.DeleteFile(destPath, cancellationToken);
                    await linkFactory.CreateSymbolicLink(ioManager.ResolvePath(file), ioManager.ResolvePath(destPath), cancellationToken);
                }));
            }
 
            using (await SemaphoreSlimContext.Lock(semaphore, cancellationToken))
            {
                await EnsureDirectories(cancellationToken);
                var ignoreFileBytes = await ioManager.ReadAllBytes(StaticIgnorePath(), cancellationToken);
                var ignoreFileText = Encoding.UTF8.GetString(ignoreFileBytes);
 
                ignoreFiles = new List<string> { StaticIgnoreFile };
 
                // we don't want to lose trailing whitespace on linux
                using (var reader = new StringReader(ignoreFileText))
                {
                    cancellationToken.ThrowIfCancellationRequested();
                    var line = await reader.ReadLineAsync(cancellationToken);
                    if (!String.IsNullOrEmpty(line))
                        ignoreFiles.Add(line);
                }
 
                var filesSymlinkTask = SymlinkBase(true);
                var dirsSymlinkTask = SymlinkBase(false);
                await ValueTaskExtensions.WhenAll(filesSymlinkTask, dirsSymlinkTask);
            }
        }
 
        public async ValueTask<ConfigurationFileResponse?> Write(string configurationRelativePath, ISystemIdentity? systemIdentity, string? previousHash, CancellationToken cancellationToken)
        {
            await EnsureDirectories(cancellationToken);
            var path = ValidateConfigRelativePath(configurationRelativePath);
 
            ConfigurationFileResponse? result = null;
 
            void WriteImpl()
            {
                try
                {
                    var fileTicket = fileTransferService.CreateUpload(FileUploadStreamKind.ForSynchronousIO);
                    var uploadCancellationToken = disposeCts.Token;
                    async Task UploadHandler()
                    {
                        await using (fileTicket)
                        {
                            var fileHash = previousHash;
                            var uploadStream = await fileTicket.GetResult(uploadCancellationToken);
                            if (uploadStream == null)
                                return; // expired
 
                            bool success = false;
                            void WriteCallback()
                            {
                                success = synchronousIOManager.WriteFileChecked(path, uploadStream, ref fileHash, cancellationToken);
                            }
 
                            if (fileTicket == null)
                            {
                                logger.LogDebug("File upload ticket for {path} expired!", path);
                                return;
                            }
 
                            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
                            {
                                if (!locked)
                                {
                                    fileTicket.SetError(ErrorCode.ConfigurationContendedAccess, null);
                                    return;
                                }
 
                                if (systemIdentity == null)
                                    await Task.Factory.StartNew(WriteCallback, cancellationToken, DefaultIOManager.BlockingTaskCreationOptions, TaskScheduler.Current);
                                else
                                    await systemIdentity.RunImpersonated(WriteCallback, cancellationToken);
                            }
 
                            if (!success)
                                fileTicket.SetError(ErrorCode.ConfigurationFileUpdated, fileHash);
                            else if (uploadStream.Length > 0)
                                postWriteHandler.HandleWrite(path);
                        }
                    }
 
                    result = new ConfigurationFileResponse
                    {
                        FileTicket = fileTicket.Ticket.FileTicket,
                        LastReadHash = previousHash,
                        IsDirectory = false,
                        AccessDenied = false,
                        Path = configurationRelativePath,
                    };
 
                    lock (disposeCts)
                        uploadTasks = Task.WhenAll(uploadTasks, UploadHandler());
                }
                catch (UnauthorizedAccessException)
                {
                    // this happens on windows, dunno about linux
                    bool isDirectory;
                    try
                    {
                        isDirectory = synchronousIOManager.IsDirectory(path);
                    }
                    catch (Exception ex)
                    {
                        logger.LogDebug(ex, "IsDirectory exception!");
                        isDirectory = false;
                    }
 
                    result = new ConfigurationFileResponse
                    {
                        Path = configurationRelativePath,
                    };
                    if (!isDirectory)
                        result.AccessDenied = true;
 
                    result.IsDirectory = isDirectory;
                }
            }
 
            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
            {
                if (!locked)
                {
                    logger.LogDebug("Contention when attempting to write file!");
                    return null;
                }
 
                if (systemIdentity == null)
                    await Task.Factory.StartNew(WriteImpl, cancellationToken, DefaultIOManager.BlockingTaskCreationOptions, TaskScheduler.Current);
                else
                    await systemIdentity.RunImpersonated(WriteImpl, cancellationToken);
            }
 
            return result;
        }
 
        public async ValueTask<bool?> CreateDirectory(string configurationRelativePath, ISystemIdentity? systemIdentity, CancellationToken cancellationToken)
        {
            await EnsureDirectories(cancellationToken);
            var path = ValidateConfigRelativePath(configurationRelativePath);
 
            bool? result = null;
            void DoCreate() => result = synchronousIOManager.CreateDirectory(path, cancellationToken);
 
            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
            {
                if (!locked)
                {
                    logger.LogDebug("Contention when attempting to create directory!");
                    return null;
                }
 
                if (systemIdentity == null)
                    await Task.Factory.StartNew(DoCreate, cancellationToken, DefaultIOManager.BlockingTaskCreationOptions, TaskScheduler.Current);
                else
                    await systemIdentity.RunImpersonated(DoCreate, cancellationToken);
            }
 
            return result!.Value;
        }
 
        public Task StartAsync(CancellationToken cancellationToken) => EnsureDirectories(cancellationToken);
 
        public Task StopAsync(CancellationToken cancellationToken) => EnsureDirectories(cancellationToken);
 
        public ValueTask HandleEvent(EventType eventType, IEnumerable<string?> parameters, bool deploymentPipeline, CancellationToken cancellationToken)
        {
            ArgumentNullException.ThrowIfNull(parameters);
 
            if (!EventTypeScriptFileNameMap.TryGetValue(eventType, out var scriptNames))
            {
                logger.LogTrace("No event script for event {event}!", eventType);
                return ValueTask.CompletedTask;
            }
 
            return ExecuteEventScripts(parameters, deploymentPipeline, cancellationToken, scriptNames);
        }
 
        public ValueTask? HandleCustomEvent(string scriptName, IEnumerable<string?> parameters, CancellationToken cancellationToken)
        {
            var scriptNameIsTgsEventName = EventTypeScriptFileNameMap
                .Values
                .SelectMany(scriptNames => scriptNames)
                .Any(tgsScriptName => tgsScriptName.Equals(
                    scriptName,
                    platformIdentifier.IsWindows
                        ? StringComparison.OrdinalIgnoreCase
                        : StringComparison.Ordinal));
            if (scriptNameIsTgsEventName)
            {
                logger.LogWarning("DMAPI attempted to execute TGS reserved event: {eventName}", scriptName);
                return null;
            }
 
#pragma warning disable CA2012 // Use ValueTasks correctly
            return ExecuteEventScripts(parameters, false, cancellationToken, scriptName);
#pragma warning restore CA2012 // Use ValueTasks correctly
        }
 
        public async ValueTask<bool?> DeleteDirectory(string configurationRelativePath, ISystemIdentity? systemIdentity, CancellationToken cancellationToken)
        {
            await EnsureDirectories(cancellationToken);
            var path = ValidateConfigRelativePath(configurationRelativePath);
 
            var result = false;
            using (SemaphoreSlimContext.TryLock(semaphore, out var locked))
            {
                if (!locked)
                {
                    logger.LogDebug("Contention when attempting to enumerate directory!");
                    return null;
                }
 
                void CheckDeleteImpl() => result = synchronousIOManager.DeleteDirectory(path);
 
                if (systemIdentity != null)
                    await systemIdentity.RunImpersonated(CheckDeleteImpl, cancellationToken);
                else
                    CheckDeleteImpl();
            }
 
            return result;
        }
 
        string StaticIgnorePath() => ioManager.ConcatPath(GameStaticFilesSubdirectory, StaticIgnoreFile);
 
        Task EnsureDirectories(CancellationToken cancellationToken)
        {
            async Task ValidateStaticFolder()
            {
                await ioManager.CreateDirectory(GameStaticFilesSubdirectory, cancellationToken);
                var staticIgnorePath = StaticIgnorePath();
                if (!await ioManager.FileExists(staticIgnorePath, cancellationToken))
                    await ioManager.WriteAllBytes(staticIgnorePath, Array.Empty<byte>(), cancellationToken);
            }
 
            async Task ValidateCodeModsFolder()
            {
                if (await ioManager.DirectoryExists(CodeModificationsSubdirectory, cancellationToken))
                    return;
 
                await ioManager.CreateDirectory(CodeModificationsSubdirectory, cancellationToken);
                var headWriteTask = ioManager.WriteAllBytes(
                    ioManager.ConcatPath(
                        CodeModificationsSubdirectory,
                        CodeModificationsHeadFile),
                    Encoding.UTF8.GetBytes(DefaultHeadInclude),
                    cancellationToken);
                var tailWriteTask = ioManager.WriteAllBytes(
                    ioManager.ConcatPath(
                        CodeModificationsSubdirectory,
                        CodeModificationsTailFile),
                    Encoding.UTF8.GetBytes(DefaultTailInclude),
                    cancellationToken);
                await ValueTaskExtensions.WhenAll(headWriteTask, tailWriteTask);
            }
 
            return Task.WhenAll(
                ValidateCodeModsFolder(),
                ioManager.CreateDirectory(EventScriptsSubdirectory, cancellationToken),
                ValidateStaticFolder());
        }
 
        string ValidateConfigRelativePath(string? configurationRelativePath)
        {
            var nullOrEmptyCheck = String.IsNullOrEmpty(configurationRelativePath);
            if (nullOrEmptyCheck)
                configurationRelativePath = DefaultIOManager.CurrentDirectory;
            if (configurationRelativePath![0] == Path.DirectorySeparatorChar || configurationRelativePath[0] == Path.AltDirectorySeparatorChar)
                configurationRelativePath = DefaultIOManager.CurrentDirectory + configurationRelativePath;
            var resolved = ioManager.ResolvePath(configurationRelativePath);
            var local = !nullOrEmptyCheck ? ioManager.ResolvePath() : null;
            if (!nullOrEmptyCheck && resolved.Length < local!.Length) // .. fuccbois
                throw new InvalidOperationException("Attempted to access file outside of configuration manager!");
            return resolved;
        }
 
        async ValueTask ExecuteEventScripts(IEnumerable<string?> parameters, bool deploymentPipeline, CancellationToken cancellationToken, params string[] scriptNames)
        {
            await EnsureDirectories(cancellationToken);
 
            // always execute in serial
            using (await SemaphoreSlimContext.Lock(semaphore, cancellationToken))
            {
                var files = await ioManager.GetFilesWithExtension(EventScriptsSubdirectory, platformIdentifier.ScriptFileExtension, false, cancellationToken);
                var resolvedScriptsDir = ioManager.ResolvePath(EventScriptsSubdirectory);
 
                var scriptFiles = files
                    .Select(x => ioManager.GetFileName(x))
                    .Where(x => scriptNames.Any(
                        scriptName => x.StartsWith(scriptName, StringComparison.Ordinal)))
                    .ToList();
 
                if (scriptFiles.Count == 0)
                {
                    logger.LogTrace("No event scripts starting with \"{scriptName}\" detected", String.Join("\" or \"", scriptNames));
                    return;
                }
 
                foreach (var scriptFile in scriptFiles)
                {
                    logger.LogTrace("Running event script {scriptFile}...", scriptFile);
                    await using (var script = await processExecutor.LaunchProcess(
                        ioManager.ConcatPath(resolvedScriptsDir, scriptFile),
                        resolvedScriptsDir,
                        String.Join(
                            ' ',
                            parameters.Select(arg =>
                            {
                                if (arg == null)
                                    return "(NULL)";
 
                                if (!arg.Contains(' ', StringComparison.Ordinal))
                                    return arg;
 
                                arg = arg.Replace("\"", "\\\"", StringComparison.Ordinal);
 
                                return $"\"{arg}\"";
                            })),
                        cancellationToken,
                        readStandardHandles: true,
                        noShellExecute: true))
                    using (cancellationToken.Register(() => script.Terminate()))
                    {
                        if (sessionConfiguration.LowPriorityDeploymentProcesses && deploymentPipeline)
                            script.AdjustPriority(false);
 
                        var exitCode = await script.Lifetime;
                        cancellationToken.ThrowIfCancellationRequested();
                        var scriptOutput = await script.GetCombinedOutput(cancellationToken);
                        if (exitCode != 0)
                            throw new JobException($"Script {scriptFile} exited with code {exitCode}:{Environment.NewLine}{scriptOutput}");
                        else
                            logger.LogDebug("Script output:{newLine}{scriptOutput}", Environment.NewLine, scriptOutput);
                    }
                }
            }
        }
    }
}