feat(ffi): unwind safety: shield FFI entrypoints with panic guard (#546)

This PR implements widely accepted Rust programming practices for dealing with panics across ABI (programming language) boundaries. - Add panic_guard.rs to wrap FFI calls and prevent panic across FFI/ABI boundary (undefined behavior). - Capture per-thread backtraces via a temporary panic hook - After a panic, subsequent invocations are poisoned. - Integrate with_unwind_guard across the engine, schema registry, and target registry exportis Signed-off-by: Anand Krishnamoorthi <anakrish@microsoft.com>
2026-08-05 02:16:11 +00:00 · 2026-01-20 21:50:10 -06:00
parent 9426b2ec02
commit 80686d6ed1
21 changed files with 1008 additions and 501 deletions
@@ -0,0 +1,84 @@
+#if REGORUS_FFI_TEST_HOOKS
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Runtime.InteropServices;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Regorus.Internal;
+
+namespace Regorus.Tests;
+
+[TestClass]
+public sealed class PanicGuardTests
+{
+    [TestInitialize]
+    public void Initialize()
+    {
+        API.regorus_engine_test_reset_poison();
+    }
+
+    [TestCleanup]
+    public void Cleanup()
+    {
+        API.regorus_engine_test_reset_poison();
+    }
+
+    [TestMethod]
+    public void Panic_produces_invalid_operation_exception()
+    {
+        var panic = Assert.ThrowsException<InvalidOperationException>(TriggerPanic);
+        StringAssert.Contains(panic.Message, "panicked", "panic message should capture payload");
+    }
+
+    [TestMethod]
+    public void Poison_flag_blocks_subsequent_calls()
+    {
+        _ = Assert.ThrowsException<InvalidOperationException>(TriggerPanic);
+        var poisoned = Assert.ThrowsException<InvalidOperationException>(TriggerPanic);
+        StringAssert.Contains(poisoned.Message, "poisoned", "poisoned message should explain guard state");
+    }
+
+    private static unsafe void TriggerPanic()
+    {
+        var result = API.regorus_engine_test_trigger_panic();
+        try
+        {
+            if (result.status == RegorusStatus.Ok)
+            {
+                return;
+            }
+
+            var message = PtrToStringUtf8((IntPtr)result.error_message);
+            throw result.status.CreateException(message);
+        }
+        finally
+        {
+            API.regorus_result_drop(result);
+        }
+    }
+
+    private static string? PtrToStringUtf8(IntPtr ptr)
+    {
+#if NETSTANDARD2_1
+        return Marshal.PtrToStringUTF8(ptr);
+#else
+        if (ptr == IntPtr.Zero)
+        {
+            return null;
+        }
+
+        var len = 0;
+        while (Marshal.ReadByte(ptr, len) != 0)
+        {
+            len++;
+        }
+
+        var buffer = new byte[len];
+        Marshal.Copy(ptr, buffer, 0, buffer.Length);
+        return System.Text.Encoding.UTF8.GetString(buffer);
+#endif
+    }
+}
+
+#endif