C#: Change random temp folder names to hash values

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/NugetPackageRestorer.cs

@@ -777,13 +777,7 @@ public void Dispose()
         /// <returns>The full path of the temp directory.</returns>
         private static string ComputeTempDirectoryPath(string srcDir, string subfolderName)
         {
-            var bytes = Encoding.Unicode.GetBytes(srcDir);
-            var sha = SHA1.HashData(bytes);
-            var sb = new StringBuilder();
-            foreach (var b in sha.Take(8))
-                sb.AppendFormat("{0:x2}", b);
-
-            return Path.Combine(FileUtils.GetTemporaryWorkingDirectory(out _), sb.ToString(), subfolderName);
+            return Path.Combine(FileUtils.GetTemporaryWorkingDirectory(out _), FileUtils.ComputeHash(srcDir), subfolderName);
         }
     }
 }

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/SourceGenerators/DotnetSourceGeneratorWrapper/DotnetSourceGeneratorWrapper.cs

@@ -37,7 +37,7 @@ public IEnumerable<string> RunSourceGenerator(IEnumerable<string> additionalFile
         {
             try
             {
-                var name = Guid.NewGuid().ToString("N").ToUpper();
+                var name = FileUtils.ComputeHash($"{csprojFile}{Environment.NewLine}{this.GetType().Name}");
                 using var tempDir = new TemporaryDirectory(Path.Join(FileUtils.GetTemporaryWorkingDirectory(out _), "source-generator"), "source generator temporary", logger);
                 var analyzerConfigPath = Path.Combine(tempDir.DirInfo.FullName, $"{name}.txt");
                 var dllPath = Path.Combine(tempDir.DirInfo.FullName, $"{name}.dll");

csharp/extractor/Semmle.Util/FileUtils.cs

@@ -91,11 +91,24 @@ public static void TryDelete(string file)
         public static string ComputeFileHash(string filePath)
         {
             using var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
-            using var shaAlg = SHA256.Create();
-            var sha = shaAlg.ComputeHash(fileStream);
+            var sha = SHA256.HashData(fileStream);
+            return GetHashString(sha);
+        }
+
+        public static string ComputeHash(string input)
+        {
+            var bytes = Encoding.Unicode.GetBytes(input);
+            var sha = MD5.HashData(bytes); // MD5 to keep it shorter than SHA256
+            return GetHashString(sha).ToUpper();
+        }
+
+        private static string GetHashString(byte[] sha)
+        {
             var hex = new StringBuilder(sha.Length * 2);
             foreach (var b in sha)
+            {
                 hex.AppendFormat("{0:x2}", b);
+            }
             return hex.ToString();
         }