C#: Download latest dotnet SDK when missing

Author: tamasvajk

csharp/autobuilder/Semmle.Autobuild.CSharp/CSharpAutobuilder.cs

@@ -50,10 +50,10 @@ public override BuildScript GetBuildScript()
                     attempt = new BuildCommandRule(DotNetRule.WithDotNet).Analyse(this, false) & CheckExtractorRun(true);
                     break;
                 case CSharpBuildStrategy.Buildless:
-                    attempt = DotNetRule.WithDotNet(this, (dotNetPath, env) =>
+                    attempt = DotNetRule.WithDotNet(this, ensureDotNetAvailable: true, (dotNetPath, env) =>
                         {
                             // No need to check that the extractor has been executed in buildless mode
-                            return new StandaloneBuildRule(dotNetPath).Analyse(this, false);
+                            return new StandaloneBuildRule(dotNetPath, env).Analyse(this, false);
                         });
                     break;
                 case CSharpBuildStrategy.MSBuild:

csharp/autobuilder/Semmle.Autobuild.CSharp/DotNetRule.cs

@@ -46,7 +46,7 @@ public BuildScript Analyse(IAutobuilder<CSharpAutobuildOptions> builder, bool au
                 builder.Log(Severity.Info, "Attempting to build using .NET Core");
             }
 
-            return WithDotNet(builder, (dotNetPath, environment) =>
+            return WithDotNet(builder, ensureDotNetAvailable: false, (dotNetPath, environment) =>
                 {
                     var ret = GetInfoCommand(builder.Actions, dotNetPath, environment);
                     foreach (var projectOrSolution in builder.ProjectsOrSolutionsToBuild)
@@ -79,10 +79,10 @@ public BuildScript Analyse(IAutobuilder<CSharpAutobuildOptions> builder, bool au
         /// variables needed by the installed .NET Core (<code>null</code> when no variables
         /// are needed).
         /// </summary>
-        public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builder, Func<string?, IDictionary<string, string>?, BuildScript> f)
+        public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builder, bool ensureDotNetAvailable, Func<string?, IDictionary<string, string>?, BuildScript> f)
         {
             var installDir = builder.Actions.PathCombine(FileUtils.GetTemporaryWorkingDirectory(builder.Actions.GetEnvironmentVariable, builder.Options.Language.UpperCaseName, out var _), ".dotnet");
-            var installScript = DownloadDotNet(builder, installDir);
+            var installScript = DownloadDotNet(builder, installDir, ensureDotNetAvailable);
             return BuildScript.Bind(installScript, installed =>
             {
                 Dictionary<string, string>? env;
@@ -100,8 +100,12 @@ public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builde
                 }
                 else
                 {
+                    // The .NET SDK was not installed, either because the installation failed or because it was already installed.
                     installDir = null;
-                    env = null;
+                    env = new Dictionary<string, string> {
+                            { "DOTNET_SKIP_FIRST_TIME_EXPERIENCE", "true" },
+                            { "MSBUILDDISABLENODEREUSE", "1" }
+                        };
                 }
 
                 return f(installDir, env);
@@ -117,14 +121,14 @@ public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builde
         /// are needed).
         /// </summary>
         public static BuildScript WithDotNet(IAutobuilder<AutobuildOptionsShared> builder, Func<IDictionary<string, string>?, BuildScript> f)
-            => WithDotNet(builder, (_1, env) => f(env));
+            => WithDotNet(builder, ensureDotNetAvailable: false, (_, env) => f(env));
 
         /// <summary>
         /// Returns a script for downloading relevant versions of the
         /// .NET Core SDK. The SDK(s) will be installed at <code>installDir</code>
         /// (provided that the script succeeds).
         /// </summary>
-        private static BuildScript DownloadDotNet(IAutobuilder<AutobuildOptionsShared> builder, string installDir)
+        private static BuildScript DownloadDotNet(IAutobuilder<AutobuildOptionsShared> builder, string installDir, bool ensureDotNetAvailable)
         {
             if (!string.IsNullOrEmpty(builder.Options.DotNetVersion))
                 // Specific version supplied in configuration: always use that
@@ -152,7 +156,28 @@ private static BuildScript DownloadDotNet(IAutobuilder<AutobuildOptionsShared> b
                 validGlobalJson = true;
             }
 
-            return validGlobalJson ? installScript : BuildScript.Failure;
+            if (validGlobalJson)
+            {
+                return installScript;
+            }
+
+            if (ensureDotNetAvailable)
+            {
+                return BuildScript.Bind(GetInfoScript(builder.Actions), (infoLines, infoRet) =>
+                {
+                    if (infoRet == 0)
+                    {
+                        return BuildScript.Failure;
+                    }
+
+                    const string latestDotNetSdkVersion = "8.0.101";
+                    builder.Log(Severity.Info, $"No .NET Core SDK found. Attempting to install version {latestDotNetSdkVersion}.");
+                    return DownloadDotNetVersion(builder, installDir, latestDotNetSdkVersion);
+                });
+
+            }
+
+            return BuildScript.Failure;
         }
 
         /// <summary>
@@ -238,6 +263,14 @@ private static BuildScript GetInstalledSdksScript(IBuildActions actions)
             return listSdks.Script;
         }
 
+        private static BuildScript GetInfoScript(IBuildActions actions)
+        {
+            var info = new CommandBuilder(actions, silent: true).
+                RunCommand("dotnet").
+                Argument("--info");
+            return info.Script;
+        }
+
         private static string DotNetCommand(IBuildActions actions, string? dotNetPath) =>
             dotNetPath is not null ? actions.PathCombine(dotNetPath, "dotnet") : "dotnet";
 

csharp/autobuilder/Semmle.Autobuild.CSharp/StandaloneBuildRule.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Collections.Generic;
 using Semmle.Autobuild.Shared;
 
 namespace Semmle.Autobuild.CSharp
@@ -9,44 +9,34 @@ namespace Semmle.Autobuild.CSharp
     internal class StandaloneBuildRule : IBuildRule<CSharpAutobuildOptions>
     {
         private readonly string? dotNetPath;
+        private readonly IDictionary<string, string>? env;
 
-        internal StandaloneBuildRule(string? dotNetPath)
+        internal StandaloneBuildRule(string? dotNetPath, IDictionary<string, string>? env)
         {
             this.dotNetPath = dotNetPath;
+            this.env = env;
         }
 
         public BuildScript Analyse(IAutobuilder<CSharpAutobuildOptions> builder, bool auto)
         {
-            BuildScript GetCommand()
+            if (!builder.Options.Buildless
+                || builder.CodeQLExtractorLangRoot is null
+                || builder.CodeQlPlatform is null)
             {
-                string standalone;
-                if (builder.CodeQLExtractorLangRoot is not null && builder.CodeQlPlatform is not null)
-                {
-                    standalone = builder.Actions.PathCombine(builder.CodeQLExtractorLangRoot, "tools", builder.CodeQlPlatform, "Semmle.Extraction.CSharp.Standalone");
-                }
-                else
-                {
-                    return BuildScript.Failure;
-                }
-
-                var cmd = new CommandBuilder(builder.Actions);
-                cmd.RunCommand(standalone);
-
-                if (!string.IsNullOrEmpty(this.dotNetPath))
-                {
-                    cmd.Argument("--dotnet");
-                    cmd.QuoteArgument(this.dotNetPath);
-                }
-
-                return cmd.Script;
+                return BuildScript.Failure;
             }
 
-            if (!builder.Options.Buildless)
+            var standalone = builder.Actions.PathCombine(builder.CodeQLExtractorLangRoot, "tools", builder.CodeQlPlatform, "Semmle.Extraction.CSharp.Standalone");
+            var cmd = new CommandBuilder(builder.Actions, environment: this.env);
+            cmd.RunCommand(standalone);
+
+            if (!string.IsNullOrEmpty(this.dotNetPath))
             {
-                return BuildScript.Failure;
+                cmd.Argument("--dotnet");
+                cmd.QuoteArgument(this.dotNetPath);
             }
 
-            return GetCommand();
+            return cmd.Script;
         }
     }
 }