C#: Use dotnet --list-runtimes to find runtime locations.

csharp/extractor/Semmle.Extraction.CSharp.Standalone/BuildAnalysis.cs

@@ -66,7 +66,7 @@ namespace Semmle.BuildAnalyser
             // Find DLLs in the .Net Framework
             if (options.ScanNetFrameworkDlls)
             {
-                var runtimeLocation = Runtime.GetRuntime(options.UseSelfContainedDotnet);
+                var runtimeLocation = new Runtime(dotnet).GetRuntime(options.UseSelfContainedDotnet);
                 progressMonitor.Log(Util.Logging.Severity.Debug, $"Runtime location selected: {runtimeLocation}");
                 dllDirNames.Add(runtimeLocation);
             }

csharp/extractor/Semmle.Extraction.CSharp.Standalone/DotNet.cs

@@ -1,5 +1,7 @@
-using System;
+using System;
+using System.Collections.Generic;
 using System.Diagnostics;
+using Semmle.Util;
 
 namespace Semmle.BuildAnalyser
 {
@@ -8,6 +10,7 @@ namespace Semmle.BuildAnalyser
     /// </summary>
     internal class DotNet
     {
+        private const string dotnet = "dotnet";
         private readonly ProgressMonitor progressMonitor;
 
         public DotNet(ProgressMonitor progressMonitor)
@@ -19,26 +22,26 @@ namespace Semmle.BuildAnalyser
         private void Info()
         {
             // TODO: make sure the below `dotnet` version is matching the one specified in global.json
-            progressMonitor.RunningProcess("dotnet --info");
-            using var proc = Process.Start("dotnet", "--info");
+            progressMonitor.RunningProcess($"{dotnet} --info");
+            using var proc = Process.Start(dotnet, "--info");
             proc.WaitForExit();
             var ret = proc.ExitCode;
 
             if (ret != 0)
             {
-                progressMonitor.CommandFailed("dotnet", "--info", ret);
-                throw new Exception($"dotnet --info failed with exit code {ret}.");
+                progressMonitor.CommandFailed(dotnet, "--info", ret);
+                throw new Exception($"{dotnet} --info failed with exit code {ret}.");
             }
         }
 
         private bool RunCommand(string args)
         {
-            progressMonitor.RunningProcess($"dotnet {args}");
-            using var proc = Process.Start("dotnet", args);
+            progressMonitor.RunningProcess($"{dotnet} {args}");
+            using var proc = Process.Start(dotnet, args);
             proc.WaitForExit();
             if (proc.ExitCode != 0)
             {
-                progressMonitor.CommandFailed("dotnet", args, proc.ExitCode);
+                progressMonitor.CommandFailed(dotnet, args, proc.ExitCode);
                 return false;
             }
 
@@ -62,5 +65,22 @@ namespace Semmle.BuildAnalyser
             var args = $"add \"{folder}\" package \"{package}\" --no-restore";
             return RunCommand(args);
         }
+
+        public IList<string> GetListedRuntimes()
+        {
+            var args = "--list-runtimes";
+            var pi = new ProcessStartInfo(dotnet, args)
+            {
+                RedirectStandardOutput = true,
+                UseShellExecute = false
+            };
+            var exitCode = pi.ReadOutput(out var runtimes);
+            if (exitCode != 0)
+            {
+                progressMonitor.CommandFailed(dotnet, args, exitCode);
+                return new List<string>();
+            }
+            return runtimes;
+        }
     }
 }

csharp/extractor/Semmle.Extraction.CSharp.Standalone/Runtime.cs

@@ -3,6 +3,8 @@ using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.IO;
 using System.Linq;
+using System.Text.RegularExpressions;
+using Semmle.BuildAnalyser;
 using Semmle.Util;
 
 namespace Semmle.Extraction.CSharp.Standalone
@@ -10,33 +12,97 @@ namespace Semmle.Extraction.CSharp.Standalone
     /// <summary>
     /// Locates .NET Runtimes.
     /// </summary>
-    internal static class Runtime
+    internal partial class Runtime
     {
+        private readonly DotNet dotNet;
+        public Runtime(DotNet dotNet) => this.dotNet = dotNet;
+
+        private sealed class Version : IComparable<Version>
+        {
+            private readonly string Dir;
+            public int Major { get; }
+            public int Minor { get; }
+            public int Patch { get; }
+
+
+            public string FullPath => Path.Combine(Dir, this.ToString());
+
+
+            public Version(string version, string dir)
+            {
+                var parts = version.Split('.');
+                Major = int.Parse(parts[0]);
+                Minor = int.Parse(parts[1]);
+                Patch = int.Parse(parts[2]);
+                Dir = dir;
+            }
+
+            public int CompareTo(Version? other) =>
+                other is null ? 1 : GetHashCode().CompareTo(other.GetHashCode());
+
+            public override bool Equals(object? obj) =>
+                obj is not null && obj is Version other && other.FullPath == FullPath;
+
+            public override int GetHashCode() =>
+                (Major * 1000 + Minor) * 1000 + Patch;
+
+            public override string ToString() =>
+                $"{Major}.{Minor}.{Patch}";
+        }
+
         private static string ExecutingRuntime => RuntimeEnvironment.GetRuntimeDirectory();
 
-        /// <summary>
-        /// Locates .NET Core Runtimes.
-        /// </summary>
-        private static IEnumerable<string> CoreRuntimes
+        private static readonly string NetCoreApp = "Microsoft.NETCore.App";
+        private static readonly string AspNetCoreApp = "Microsoft.AspNetCore.App";
+
+        private static void AddOrUpdate(Dictionary<string, Version> dict, string framework, Version version)
         {
-            get
+            if (!dict.TryGetValue(framework, out var existing) || existing.CompareTo(version) < 0)
             {
-                var dotnetPath = FileUtils.FindProgramOnPath(Win32.IsWindows() ? "dotnet.exe" : "dotnet");
-                var dotnetDirs = dotnetPath is not null
-                    ? new[] { dotnetPath }
-                    : new[] { "/usr/share/dotnet", @"C:\Program Files\dotnet" };
-                var coreDirs = dotnetDirs.Select(d => Path.Combine(d, "shared", "Microsoft.NETCore.App"));
-
-                var dir = coreDirs.FirstOrDefault(Directory.Exists);
-                if (dir is not null)
-                {
-                    return Directory.EnumerateDirectories(dir).OrderByDescending(Path.GetFileName);
-                }
-
-                return Enumerable.Empty<string>();
+                dict[framework] = version;
             }
         }
 
+        [GeneratedRegex(@"^(\S+)\s(\d+\.\d+\.\d+)\s\[(\S+)\]$")]
+        private static partial Regex RuntimeRegex();
+
+        /// <summary>
+        /// Parses the output of `dotnet --list-runtimes` to get a map from a runtime to the location of
+        /// the newest version of the runtime.
+        /// It is assume that the format of a listed runtime is something like:
+        /// Microsoft.NETCore.App 7.0.2 [/usr/share/dotnet/shared/Microsoft.NETCore.App]
+        /// </summary>
+        private static Dictionary<string, Version> ParseRuntimes(IList<string> listed)
+        {
+            // Parse listed runtimes.
+            var runtimes = new Dictionary<string, Version>();
+            listed.ForEach(r =>
+            {
+                var match = RuntimeRegex().Match(r);
+                if (match.Success)
+                {
+                    AddOrUpdate(runtimes, match.Groups[1].Value, new Version(match.Groups[2].Value, match.Groups[3].Value));
+                }
+            });
+
+            return runtimes;
+        }
+
+        private Dictionary<string, Version> GetNewestRuntimes()
+        {
+            try
+            {
+                var listed = dotNet.GetListedRuntimes();
+                return ParseRuntimes(listed);
+            }
+            catch (Exception ex)
+                when (ex is System.ComponentModel.Win32Exception || ex is FileNotFoundException)
+            {
+                return new Dictionary<string, Version>();
+            }
+        }
+
+
         /// <summary>
         /// Locates .NET Desktop Runtimes.
         /// This includes Mono and Microsoft.NET.
@@ -69,24 +135,33 @@ namespace Semmle.Extraction.CSharp.Standalone
             }
         }
 
+        private IEnumerable<string> GetRuntimes()
+        {
+            // Gets the newest version of the installed runtimes.
+            var newestRuntimes = GetNewestRuntimes();
+
+            // Location of the newest .NET Core Runtime.
+            if (newestRuntimes.TryGetValue(NetCoreApp, out var netCoreApp))
+            {
+                yield return netCoreApp.FullPath;
+            }
+
+            // Location of the newest ASP.NET Core Runtime.
+            if (newestRuntimes.TryGetValue(AspNetCoreApp, out var aspNetCoreApp))
+            {
+                yield return aspNetCoreApp.FullPath;
+            }
+
+            foreach (var r in DesktopRuntimes)
+                yield return r;
+
+            // A bad choice if it's the self-contained runtime distributed in codeql dist.
+            yield return ExecutingRuntime;
+        }
+
         /// <summary>
         /// Gets the .NET runtime location to use for extraction
         /// </summary>
-        public static string GetRuntime(bool useSelfContained) => useSelfContained ? ExecutingRuntime : Runtimes.First();
-
-        private static IEnumerable<string> Runtimes
-        {
-            get
-            {
-                foreach (var r in CoreRuntimes)
-                    yield return r;
-
-                foreach (var r in DesktopRuntimes)
-                    yield return r;
-
-                // A bad choice if it's the self-contained runtime distributed in codeql dist.
-                yield return ExecutingRuntime;
-            }
-        }
+        public string GetRuntime(bool useSelfContained) => useSelfContained ? ExecutingRuntime : GetRuntimes().First();
     }
 }