C#: Enable nullability on Semmle.Extraction.CIL.Driver (#4114)

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CIL.Driver/ExtractorOptions.cs

@@ -50,6 +50,13 @@ static AssemblyName CreateAssemblyName(MetadataReader mdReader, AssemblyDefiniti
             return an;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AssemblyInfo"/> class.
+        /// </summary>
+        /// <param name="path">Path of the assembly.</param>
+        /// <exception cref="Semmle.Extraction.CIL.Driver.InvalidAssemblyException">
+        /// Thrown when the input file is not a valid assembly.
+        /// </exception>
         public AssemblyInfo(string path)
         {
             filename = path;
@@ -60,13 +67,11 @@ public AssemblyInfo(string path)
             {
                 try
                 {
-                    isAssembly = peReader.HasMetadata;
-                    if (!isAssembly) return;
+                    if (!peReader.HasMetadata) throw new InvalidAssemblyException();
 
                     var mdReader = peReader.GetMetadataReader();
 
-                    isAssembly = mdReader.IsAssembly;
-                    if (!mdReader.IsAssembly) return;
+                    if (!mdReader.IsAssembly) throw new InvalidAssemblyException();
 
                     // Get our own assembly name
                     name = CreateAssemblyName(mdReader, mdReader.GetAssemblyDefinition());
@@ -81,15 +86,14 @@ public AssemblyInfo(string path)
                     // This failed on one of the Roslyn tests that includes
                     // a deliberately malformed assembly.
                     // In this case, we just skip the extraction of this assembly.
-                    isAssembly = false;
+                    throw new InvalidAssemblyException();
                 }
             }
         }
 
         public readonly AssemblyName name;
         public readonly string filename;
         public bool extract;
-        public readonly bool isAssembly;
         public readonly AssemblyName[] references;
     }
 
@@ -102,11 +106,12 @@ class AssemblyList
     {
         class AssemblyNameComparer : IEqualityComparer<AssemblyName>
         {
-            bool IEqualityComparer<AssemblyName>.Equals(AssemblyName x, AssemblyName y) =>
-                x.Name == y.Name && x.Version == y.Version;
+            bool IEqualityComparer<AssemblyName>.Equals(AssemblyName? x, AssemblyName? y) =>
+                object.ReferenceEquals(x, y) ||
+                x?.Name == y?.Name && x?.Version == y?.Version;
 
             int IEqualityComparer<AssemblyName>.GetHashCode(AssemblyName obj) =>
-                obj.Name.GetHashCode() + 7 * obj.Version.GetHashCode();
+                (obj.Name, obj.Version).GetHashCode();
         }
 
         readonly Dictionary<AssemblyName, AssemblyInfo> assembliesRead = new Dictionary<AssemblyName, AssemblyInfo>(new AssemblyNameComparer());
@@ -116,13 +121,15 @@ public void AddFile(string assemblyPath, bool extractAll)
             if (!filesAnalyzed.Contains(assemblyPath))
             {
                 filesAnalyzed.Add(assemblyPath);
-                var info = new AssemblyInfo(assemblyPath);
-                if (info.isAssembly)
+                try
                 {
+                    var info = new AssemblyInfo(assemblyPath);
                     info.extract = extractAll;
                     if (!assembliesRead.ContainsKey(info.name))
                         assembliesRead.Add(info.name, info);
                 }
+                catch (InvalidAssemblyException)
+                { }
             }
         }
 
@@ -137,8 +144,7 @@ public void ResolveReferences()
             while (assembliesToReference.Any())
             {
                 var item = assembliesToReference.Pop();
-                AssemblyInfo info;
-                if (assembliesRead.TryGetValue(item, out info))
+                if (assembliesRead.TryGetValue(item, out AssemblyInfo? info))
                 {
                     if (!info.extract)
                     {
@@ -165,6 +171,21 @@ class ExtractorOptions
     {
         readonly AssemblyList assemblyList = new AssemblyList();
 
+        public ExtractorOptions(string[] args)
+        {
+            Verbosity = Verbosity.Info;
+            Threads = System.Environment.ProcessorCount;
+            PDB = true;
+            TrapCompression = TrapWriter.CompressionMode.Gzip;
+
+            ParseArgs(args);
+
+            AddFrameworkDirectories(false);
+
+            assemblyList.ResolveReferences();
+            AssembliesToExtract = assemblyList.AssembliesToExtract.ToArray();
+        }
+
         public void AddDirectory(string directory, bool extractAll)
         {
             foreach (var file in
@@ -192,21 +213,20 @@ void AddFileOrDirectory(string path)
             if (File.Exists(path))
             {
                 assemblyList.AddFile(path, true);
-                AddDirectory(Path.GetDirectoryName(path), false);
+                string? directory = Path.GetDirectoryName(path);
+                if (directory is null)
+                {
+                    throw new InternalError($"Directory of path '{path}' is null");
+                }
+                AddDirectory(directory, false);
             }
             else if (Directory.Exists(path))
             {
                 AddDirectory(path, true);
             }
         }
 
-        void ResolveReferences()
-        {
-            assemblyList.ResolveReferences();
-            AssembliesToExtract = assemblyList.AssembliesToExtract.ToArray();
-        }
-
-        public IEnumerable<AssemblyInfo> AssembliesToExtract { get; private set; }
+        public IEnumerable<AssemblyInfo> AssembliesToExtract { get; }
 
         /// <summary>
         /// Gets the assemblies that were referenced but were not available to be
@@ -215,55 +235,43 @@ void ResolveReferences()
         /// </summary>
         public IEnumerable<AssemblyName> MissingReferences => assemblyList.missingReferences;
 
-        public static ExtractorOptions ParseCommandLine(string[] args)
+        private void ParseArgs(string[] args)
         {
-            var options = new ExtractorOptions();
-            options.Verbosity = Verbosity.Info;
-            options.Threads = System.Environment.ProcessorCount;
-            options.PDB = true;
-            options.TrapCompression = TrapWriter.CompressionMode.Gzip;
-
             foreach (var arg in args)
             {
                 if (arg == "--verbose")
                 {
-                    options.Verbosity = Verbosity.All;
+                    Verbosity = Verbosity.All;
                 }
                 else if (arg == "--silent")
                 {
-                    options.Verbosity = Verbosity.Off;
+                    Verbosity = Verbosity.Off;
                 }
                 else if (arg.StartsWith("--verbosity:"))
                 {
-                    options.Verbosity = (Verbosity)int.Parse(arg.Substring(12));
+                    Verbosity = (Verbosity)int.Parse(arg.Substring(12));
                 }
                 else if (arg == "--dotnet")
                 {
-                    options.AddFrameworkDirectories(true);
+                    AddFrameworkDirectories(true);
                 }
                 else if (arg == "--nocache")
                 {
-                    options.NoCache = true;
+                    NoCache = true;
                 }
                 else if (arg.StartsWith("--threads:"))
                 {
-                    options.Threads = int.Parse(arg.Substring(10));
+                    Threads = int.Parse(arg.Substring(10));
                 }
                 else if (arg == "--no-pdb")
                 {
-                    options.PDB = false;
+                    PDB = false;
                 }
                 else
                 {
-                    options.AddFileOrDirectory(arg);
+                    AddFileOrDirectory(arg);
                 }
             }
-
-            options.AddFrameworkDirectories(false);
-            options.ResolveReferences();
-
-            return options;
         }
-
     }
 }

csharp/extractor/Semmle.Extraction.CIL.Driver/InvalidAssemblyException.cs

@@ -0,0 +1,7 @@
+using System;
+
+namespace Semmle.Extraction.CIL.Driver
+{
+    class InvalidAssemblyException : Exception
+    { }
+}

csharp/extractor/Semmle.Extraction.CIL.Driver/Program.cs

@@ -40,7 +40,7 @@ static void Main(string[] args)
                 return;
             }
 
-            var options = ExtractorOptions.ParseCommandLine(args);
+            var options = new ExtractorOptions(args);
             var layout = new Layout();
             var logger = new ConsoleLogger(options.Verbosity);
 

csharp/extractor/Semmle.Extraction.CIL.Driver/Semmle.Extraction.CIL.Driver.csproj

@@ -7,6 +7,7 @@
     <RootNamespace>Semmle.Extraction.CIL.Driver</RootNamespace>
     <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
     <RuntimeIdentifiers>win-x64;linux-x64;osx-x64</RuntimeIdentifiers>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>