fix local testing & isolate & C# processing

compose.yaml

@@ -26,6 +26,7 @@
 
   worker:
     image: liquidcode-tester-worker:latest
+    privileged: true
     container_name: liquidcode-tester-worker
     build:
       context: .
@@ -36,16 +37,9 @@
       - ASPNETCORE_ENVIRONMENT=Development
     networks:
       - liquidcode-network
-    # Security hardening for Worker
-    security_opt:
-      - no-new-privileges:true
-      - apparmor=docker-default
-    cap_drop:
-      - ALL
-    cap_add:
-      - SYS_ADMIN  # Required for Isolate namespaces
-      - SETUID     # Required for Isolate to change user context
-      - SETGID     # Required for Isolate to change group context
+    # Mount cgroup for Isolate sandbox
+    volumes:
+      - /sys/fs/cgroup:/sys/fs/cgroup:rw
     # Temporary filesystem for compilation and testing
     tmpfs:
       - /tmp:exec,size=4G

src/LiquidCode.Tester.Gateway/Services/WorkerClientService.cs

@@ -35,7 +35,7 @@ public class WorkerClientService : IWorkerClientService
             form.Add(new StringContent(submit.MissionId.ToString()), "MissionId");
             form.Add(new StringContent(submit.Language), "Language");
             form.Add(new StringContent(submit.LanguageVersion), "LanguageVersion");
-            form.Add(new StringContent(submit.SourceCode), "SourceCode");
+            form.Add(new StringContent(submit.SourceCode, System.Text.Encoding.UTF8, "text/plain"), "SourceCode");
             form.Add(new StringContent(submit.CallbackUrl), "CallbackUrl");
 
             // Add package file

src/LiquidCode.Tester.Worker/Dockerfile

@@ -82,10 +82,8 @@ RUN apt-get update && \
     && rm -rf /var/lib/apt/lists/*
 
 # Create unprivileged user for running the worker service
-RUN useradd -m -u 1001 -s /bin/bash workeruser && \
-    mkdir -p /var/local/lib/isolate && \
-    chmod 755 /var/local/lib/isolate && \
-    chown -R workeruser:workeruser /var/local/lib/isolate
+RUN mkdir -p /var/local/lib/isolate && \
+    chmod 755 /var/local/lib/isolate
 
 # Configure isolate directories and control-group root
 RUN printf "box_root = /var/local/lib/isolate\nlock_root = /run/isolate/locks\ncg_root = /sys/fs/cgroup\nfirst_uid = 60000\nfirst_gid = 60000\nnum_boxes = 1000\n" > /usr/local/etc/isolate.conf && \
@@ -96,13 +94,11 @@ RUN printf "box_root = /var/local/lib/isolate\nlock_root = /run/isolate/locks\nc
 COPY --from=publish /app/publish .
 
 # Create temp directory for compilation and testing with proper permissions
-RUN mkdir -p /tmp/testing && \
-    chown -R workeruser:workeruser /tmp/testing && \
-    chown -R workeruser:workeruser /app
+RUN mkdir -p /tmp/testing
 
 ENV ASPNETCORE_URLS=http://+:8080
 
 # Switch to unprivileged user
-USER workeruser
+#USER workeruser
 
 ENTRYPOINT ["dotnet", "LiquidCode.Tester.Worker.dll"]

src/LiquidCode.Tester.Worker/Services/CSharpCompilationServiceIsolate.cs

@@ -103,7 +103,10 @@ public class CSharpCompilationServiceIsolate : ICompilationService
                 DirectoryBindings = new List<DirectoryBinding>
                 {
                     new DirectoryBinding { HostPath = "/usr/lib", SandboxPath = "/usr/lib", ReadOnly = true },
-                    new DirectoryBinding { HostPath = "/lib", SandboxPath = "/lib", ReadOnly = true }
+                    new DirectoryBinding { HostPath = "/lib", SandboxPath = "/lib", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/usr/bin", SandboxPath = "/usr/bin", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/usr/share", SandboxPath = "/usr/share", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/etc/mono", SandboxPath = "/etc/mono", ReadOnly = true }
                 }
             });
 

src/LiquidCode.Tester.Worker/Services/CSharpExecutionServiceIsolate.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using LiquidCode.Tester.Worker.Services.Isolate;
+using System.Collections.Generic;
 
 namespace LiquidCode.Tester.Worker.Services;
 
@@ -63,6 +64,7 @@ public class CSharpExecutionServiceIsolate : IExecutionService
 
             // Prepare input/output files inside the sandbox
             var outputFilePath = Path.Combine(boxDir, "output.txt");
+            var stderrFilePath = Path.Combine(boxDir, "stderr.txt");
             string? sandboxInputPath = null;
 
             if (!string.IsNullOrEmpty(inputFilePath) && File.Exists(inputFilePath))
@@ -71,20 +73,30 @@ public class CSharpExecutionServiceIsolate : IExecutionService
                 File.Copy(inputFilePath, sandboxInputPath, overwrite: true);
             }
 
-            // Run in Isolate
+            // Run in Isolate using mono runtime
             var isolateResult = await _isolateService.RunAsync(new IsolateRunOptions
             {
                 BoxId = boxId,
-                Executable = $"/box/{executableName}",
+                Executable = "/usr/bin/mono",
+                Arguments = new[] { $"/box/{executableName}" },
                 TimeLimitSeconds = timeLimitMs / 1000.0,
                 WallTimeLimitSeconds = (timeLimitMs / 1000.0) * 2,
                 MemoryLimitKb = memoryLimitMb * 1024,
                 StackLimitKb = 256 * 1024,
-                ProcessLimit = 1, // Single process for C#
+                ProcessLimit = 64, // Mono may create multiple threads/processes
                 EnableNetwork = false,
                 StdinFile = sandboxInputPath,
                 StdoutFile = outputFilePath,
-                WorkingDirectory = "/box"
+                StderrFile = stderrFilePath,
+                WorkingDirectory = "/box",
+                DirectoryBindings = new List<DirectoryBinding>
+                {
+                    new DirectoryBinding { HostPath = "/usr/lib", SandboxPath = "/usr/lib", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/lib", SandboxPath = "/lib", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/usr/share", SandboxPath = "/usr/share", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/etc/mono", SandboxPath = "/etc/mono", ReadOnly = true },
+                    new DirectoryBinding { HostPath = "/usr/bin", SandboxPath = "/usr/bin", ReadOnly = true }
+                }
             });
 
             stopwatch.Stop();
@@ -95,10 +107,19 @@ public class CSharpExecutionServiceIsolate : IExecutionService
                 result.Output = await File.ReadAllTextAsync(outputFilePath);
             }
 
+            // Read stderr
+            var stderrContent = string.Empty;
+            if (File.Exists(stderrFilePath))
+            {
+                stderrContent = await File.ReadAllTextAsync(stderrFilePath);
+            }
+
             // Map Isolate result to ExecutionResult
             result.ExecutionTimeMs = (long)(isolateResult.CpuTimeSeconds * 1000);
             result.MemoryUsedMb = isolateResult.MemoryUsedKb / 1024;
-            result.ErrorOutput = isolateResult.ErrorOutput;
+            result.ErrorOutput = string.IsNullOrEmpty(stderrContent)
+                ? isolateResult.ErrorOutput
+                : $"{stderrContent}\n{isolateResult.ErrorOutput}".Trim();
             result.ExitCode = isolateResult.ExitCode;
 
             if (isolateResult.TimeLimitExceeded)