C#: autobuild: fix buildless mode for CodeQL

Author: aibaars

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

@@ -11,10 +11,15 @@ public BuildScript Analyse(Autobuilder builder, bool auto)
         {
             BuildScript GetCommand(string? solution)
             {
-                if (builder.SemmlePlatformTools is null)
+                string standalone;
+                if (!(builder.CodeQLExtractorLangRoot is null) && !(builder.CodeQlPlatform is null)) {
+                    standalone = builder.Actions.PathCombine(builder.CodeQLExtractorLangRoot, "tools", builder.CodeQlPlatform, "Semmle.Extraction.CSharp.Standalone");
+                } else if (!(builder.SemmlePlatformTools is null)) {
+                    standalone = builder.Actions.PathCombine(builder.SemmlePlatformTools, "csharp", "Semmle.Extraction.CSharp.Standalone");
+                } else {
                     return BuildScript.Failure;
+                }
 
-                var standalone = builder.Actions.PathCombine(builder.SemmlePlatformTools, "csharp", "Semmle.Extraction.CSharp.Standalone");
                 var cmd = new CommandBuilder(builder.Actions);
                 cmd.RunCommand(standalone);
 

csharp/autobuilder/Semmle.Autobuild.Shared/Autobuilder.cs

@@ -193,6 +193,8 @@ public Autobuilder(IBuildActions actions, AutobuildOptions options)
             SemmleDist = Actions.GetEnvironmentVariable("SEMMLE_DIST");
             SemmlePlatformTools = Actions.GetEnvironmentVariable("SEMMLE_PLATFORM_TOOLS");
 
+            CodeQlPlatform = Actions.GetEnvironmentVariable("CODEQL_PLATFORM");
+
             JavaHome =
                 Actions.GetEnvironmentVariable("CODEQL_JAVA_HOME") ??
                 Actions.GetEnvironmentVariable("SEMMLE_JAVA_HOME") ??
@@ -271,7 +273,7 @@ protected BuildScript AutobuildFailure() =>
         /// <summary>
         /// Value of CODEQL_EXTRACTOR_<LANG>_ROOT environment variable.
         /// </summary>
-        private string? CodeQLExtractorLangRoot { get; }
+        public string? CodeQLExtractorLangRoot { get; }
 
         /// <summary>
         /// Value of SEMMLE_DIST environment variable.
@@ -287,6 +289,11 @@ protected BuildScript AutobuildFailure() =>
         /// </summary>
         public string? SemmlePlatformTools { get; }
 
+        /// <summary>
+        /// Value of CODEQL_PLATFORM environment variable.
+        /// </summary>
+        public string? CodeQlPlatform { get; }
+
         /// <summary>
         /// The absolute path of the odasa executable.
         /// null if we are running in CodeQL.