From ef4f9ba74d6207395093655d2d5012d7d7a07234 Mon Sep 17 00:00:00 2001
From: Aiken Harris <harraiken91@gmail.com>
Date: Tue, 30 Jun 2026 22:21:30 +0200
Subject: [PATCH] Introduce very basic exception handling support

---
 sdk/xtdk/rtltypes.h            | 10 ++++
 xtoskrnl/CMakeLists.txt        |  1 +
 xtoskrnl/includes/rtl.hh       |  1 +
 xtoskrnl/includes/rtl/exsup.hh | 27 +++++++++++
 xtoskrnl/rtl/exsup.cc          | 89 ++++++++++++++++++++++++++++++++++
 5 files changed, 128 insertions(+)
 create mode 100644 xtoskrnl/includes/rtl/exsup.hh
 create mode 100644 xtoskrnl/rtl/exsup.cc

diff --git a/sdk/xtdk/rtltypes.h b/sdk/xtdk/rtltypes.h
index 7f1f96a..7fdd284 100644
--- a/sdk/xtdk/rtltypes.h
+++ b/sdk/xtdk/rtltypes.h
@@ -32,6 +32,16 @@
 #define DOUBLE_SCIENTIFIC_PRECISION                     -4
 #define DOUBLE_SIGN_BIT                                 0x8000000000000000ULL
 
+/* Exception Record flags */
+#define EXCEPTION_CONTINUE_SEARCH                       0x00
+#define EXCEPTION_NONCONTINUABLE                        0x01
+#define EXCEPTION_UNWINDING                             0x02
+#define EXCEPTION_EXIT_UNWIND                           0x04
+#define EXCEPTION_STACK_INVALID                         0x08
+#define EXCEPTION_NESTED_CALL                           0x10
+#define EXCEPTION_TARGET_UNWIND                         0x20
+#define EXCEPTION_COLLIDED_UNWIND                       0x40
+
 /* Maximum number of lead bytes for NLS */
 #define NLS_MAXIMUM_LEADBYTES                           12
 
diff --git a/xtoskrnl/CMakeLists.txt b/xtoskrnl/CMakeLists.txt
index 3a1c242..db6f401 100644
--- a/xtoskrnl/CMakeLists.txt
+++ b/xtoskrnl/CMakeLists.txt
@@ -100,6 +100,7 @@ list(APPEND XTOSKRNL_SOURCE
     ${XTOSKRNL_SOURCE_DIR}/rtl/data.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/endian.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/exports.cc
+    ${XTOSKRNL_SOURCE_DIR}/rtl/exsup.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/guid.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/lifo.cc
     ${XTOSKRNL_SOURCE_DIR}/rtl/llist.cc
diff --git a/xtoskrnl/includes/rtl.hh b/xtoskrnl/includes/rtl.hh
index 610ca79..b27b08d 100644
--- a/xtoskrnl/includes/rtl.hh
+++ b/xtoskrnl/includes/rtl.hh
@@ -17,6 +17,7 @@
 #include <rtl/bitmap.hh>
 #include <rtl/dispatch.hh>
 #include <rtl/endian.hh>
+#include <rtl/exsup.hh>
 #include <rtl/guid.hh>
 #include <rtl/lifo.hh>
 #include <rtl/llist.hh>
diff --git a/xtoskrnl/includes/rtl/exsup.hh b/xtoskrnl/includes/rtl/exsup.hh
new file mode 100644
index 0000000..d221c98
--- /dev/null
+++ b/xtoskrnl/includes/rtl/exsup.hh
@@ -0,0 +1,27 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/includes/rtl/exsup.hh
+ * DESCRIPTION:     Exception handling
+ * DEVELOPERS:      Aiken Harris <harraiken91@gmail.com>
+ */
+
+#ifndef __XTOSKRNL_RTL_EXSUP_HH
+#define __XTOSKRNL_RTL_EXSUP_HH
+
+#include <xtos.hh>
+
+
+/* Runtime Library */
+namespace RTL
+{
+    class Exception
+    {
+        public:
+            STATIC XTAPI VOID RaiseException(IN PEXCEPTION_RECORD ExceptionRecord);
+            STATIC XTAPI VOID RaiseStatus(IN XTSTATUS Status);
+            STATIC XTAPI LONG SystemFilter(VOID);
+    };
+}
+
+#endif /* __XTOSKRNL_RTL_EXSUP_HH */
diff --git a/xtoskrnl/rtl/exsup.cc b/xtoskrnl/rtl/exsup.cc
new file mode 100644
index 0000000..5486c77
--- /dev/null
+++ b/xtoskrnl/rtl/exsup.cc
@@ -0,0 +1,89 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/rtl/exsup.cc
+ * DESCRIPTION:     Exception handling
+ * DEVELOPERS:      Aiken Harris <harraiken91@gmail.com>
+ */
+
+#include <xtos.hh>
+
+
+/**
+ * Raises a structured exception using an exception record.
+ *
+ * @param ExceptionRecord
+ *        Supplies a pointer to the exception record containing details.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+RTL::Exception::RaiseException(IN PEXCEPTION_RECORD ExceptionRecord)
+{
+    /* Not implemented */
+    UNIMPLEMENTED;
+
+    /* Disable interrupts */
+    AR::CpuFunctions::ClearInterruptFlag();
+
+    /* Halt the system */
+    KE::Crash::Panic(ExceptionRecord->ExceptionCode);
+}
+
+/**
+ * Raises a structured exception based on the provided status code.
+ *
+ * @param Status
+ *        Supplies the status code to be raised as an exception.
+ *
+ * @return This routine does not return any value.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+VOID
+RTL::Exception::RaiseStatus(IN XTSTATUS Status)
+{
+    EXCEPTION_RECORD ExceptionRecord;
+
+    /* Not implemented */
+    UNIMPLEMENTED;
+
+    /* Create a basic exception record */
+    ExceptionRecord.ExceptionAddress = _ReturnAddress();
+    ExceptionRecord.ExceptionCode = Status;
+    ExceptionRecord.ExceptionRecord = NULLPTR;
+    ExceptionRecord.NumberParameters = 0;
+    ExceptionRecord.ExceptionFlags = EXCEPTION_NONCONTINUABLE;
+
+    /* Dispatch the exception */
+    RaiseException(&ExceptionRecord);
+}
+
+/**
+ * Determines whether a SEH exception should be handled or lead to a kernel panic based on the processor mode.
+ *
+ * @return This routine returns EXCEPTION_EXECUTE_HANDLER if the CPU was in UserMode,
+ *         or EXCEPTION_CONTINUE_SEARCH if the CPU was in KernelMode.
+ *
+ * @since XT 1.0
+ */
+XTAPI
+LONG
+RTL::Exception::SystemFilter(VOID)
+{
+    /* Check if the exception originated from kernel-mode execution */
+    if(KE::Processor::GetCurrentThread()->PreviousMode == KernelMode)
+    {
+        /* Kernel-mode fault, force a kernel panic */
+        return EXCEPTION_CONTINUE_SEARCH;
+    }
+    else
+    {
+        /* User-mode fault, catch it and return the error status gracefully */
+        return EXCEPTION_EXECUTE_HANDLER;
+    }
+}