From 68ae449731f382dedf8e8382ae920d420a998eef Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sat, 21 Mar 2026 10:33:01 +0000
Subject: [PATCH] toolchain: xpcg: add an offset type for signed offset values

---
 toolchain/xpcg/backend/c-mpc/backend.c | 26 ++++++++++++++++++++++++++
 toolchain/xpcg/ctx.c                   |  4 ++++
 toolchain/xpcg/type.h                  |  1 +
 3 files changed, 31 insertions(+)

diff --git a/toolchain/xpcg/backend/c-mpc/backend.c b/toolchain/xpcg/backend/c-mpc/backend.c
index 6fb4aa5..5cd32e6 100644
--- a/toolchain/xpcg/backend/c-mpc/backend.c
+++ b/toolchain/xpcg/backend/c-mpc/backend.c
@@ -176,6 +176,9 @@ static int emit_msg_struct_member(
 	case TYPE_SIZE:
 		emit(ctx, "uint64_t %s;\n", param->p_name);
 		break;
+	case TYPE_OFFSET:
+		emit(ctx, "int64_t %s;\n", param->p_name);
+		break;
 	case TYPE_STRING:
 	case TYPE_BUFFER:
 		emit(ctx, "uint16_t %s_offset;\n", param->p_name);
@@ -336,6 +339,7 @@ static int emit_interface_msg_function_send_impl(
 		switch (param->p_type->ty_id) {
 		case TYPE_INT:
 		case TYPE_SIZE:
+		case TYPE_OFFSET:
 			emit(ctx,
 			     "msg_data.msg_request.%s = %s;\n\n",
 			     param->p_name,
@@ -578,6 +582,9 @@ static int emit_interface_msg_function_send(
 		case TYPE_SIZE:
 			emit(ctx, "size_t %s", param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx, "off_t %s", param->p_name);
+			break;
 		case TYPE_STRING:
 			emit(ctx, "const char *%s", param->p_name);
 			break;
@@ -604,6 +611,9 @@ static int emit_interface_msg_function_send(
 		case TYPE_SIZE:
 			emit(ctx, "size_t *out_%s", param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx, "off_t *out_%s", param->p_name);
+			break;
 		case TYPE_HANDLE:
 			emit(ctx, "kern_handle_t *out_%s", param->p_name);
 			break;
@@ -681,6 +691,12 @@ static int emit_interface_dispatcher_impl_msg(
 			     param->p_name,
 			     param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx,
+			     "off_t %s = " MSG_STRUCT_NAME ".msg_request.%s;\n",
+			     param->p_name,
+			     param->p_name);
+			break;
 		case TYPE_STRING:
 			emit(ctx,
 			     "xpc_string_t %s = "
@@ -719,6 +735,9 @@ static int emit_interface_dispatcher_impl_msg(
 		case TYPE_SIZE:
 			emit(ctx, "size_t %s = 0;\n", param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx, "off_t %s = 0;\n", param->p_name);
+			break;
 		case TYPE_HANDLE:
 			emit(ctx,
 			     "kern_handle_t %s = KERN_HANDLE_INVALID;\n",
@@ -795,6 +814,7 @@ static int emit_interface_dispatcher_impl_msg(
 			= b_unbox(struct msg_parameter, entry, p_entry);
 		switch (param->p_type->ty_id) {
 		case TYPE_INT:
+		case TYPE_OFFSET:
 			emit(ctx,
 			     MSG_STRUCT_NAME ".msg_response.%s = %s;\n",
 			     param->p_name,
@@ -976,6 +996,9 @@ static int emit_interface_vtable_entry(
 		case TYPE_SIZE:
 			emit(ctx, "size_t %s", param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx, "off_t %s", param->p_name);
+			break;
 		case TYPE_BUFFER:
 			emit(ctx, "const xpc_buffer_t *%s", param->p_name);
 			break;
@@ -1012,6 +1035,9 @@ static int emit_interface_vtable_entry(
 		case TYPE_SIZE:
 			emit(ctx, "size_t *out_%s", param->p_name);
 			break;
+		case TYPE_OFFSET:
+			emit(ctx, "off_t *out_%s", param->p_name);
+			break;
 		case TYPE_BUFFER:
 			emit(ctx, "xpc_buffer_t *out_%s", param->p_name);
 			break;
diff --git a/toolchain/xpcg/ctx.c b/toolchain/xpcg/ctx.c
index d347f96..18a3e26 100644
--- a/toolchain/xpcg/ctx.c
+++ b/toolchain/xpcg/ctx.c
@@ -47,6 +47,10 @@ const struct type *ctx_get_type(struct ctx *ctx, const char *name)
 		return ctx_get_builtin_type(ctx, TYPE_SIZE);
 	}
 
+	if (!strcmp(name, "offset")) {
+		return ctx_get_builtin_type(ctx, TYPE_OFFSET);
+	}
+
 	if (!strcmp(name, "buffer")) {
 		return ctx_get_builtin_type(ctx, TYPE_BUFFER);
 	}
diff --git a/toolchain/xpcg/type.h b/toolchain/xpcg/type.h
index f36d4ac..2252608 100644
--- a/toolchain/xpcg/type.h
+++ b/toolchain/xpcg/type.h
@@ -4,6 +4,7 @@
 enum type_id {
 	TYPE_NONE,
 	TYPE_INT,
+	TYPE_OFFSET,
 	TYPE_SIZE,
 	TYPE_STRING,
 	TYPE_BUFFER,