From 04617e81e3ceadf3c0d1f1ff51fe8292a0a63508 Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sun, 29 Mar 2026 11:50:37 +0100
Subject: [PATCH] kernel: add a syscall to query generic information about an
 object

---
 include/kernel/syscall.h             |  3 +++
 libmango/arch/x86_64/syscall.S       |  1 +
 libmango/include-user/mango/object.h |  3 +++
 libmango/include/mango/syscall.h     |  1 +
 libmango/include/mango/types.h       |  4 ++++
 syscall/dispatch.c                   |  1 +
 syscall/object.c                     | 29 ++++++++++++++++++++++++++++
 7 files changed, 42 insertions(+)

diff --git a/include/kernel/syscall.h b/include/kernel/syscall.h
index a8e281a..1261a64 100644
--- a/include/kernel/syscall.h
+++ b/include/kernel/syscall.h
@@ -195,6 +195,9 @@ extern kern_status_t sys_msg_write(
 extern kern_status_t sys_kern_object_wait(
 	kern_wait_item_t *items,
 	size_t nr_items);
+extern kern_status_t sys_kern_object_query(
+	kern_handle_t object,
+	kern_object_info_t *out);
 
 extern kern_status_t sys_vm_controller_create(kern_handle_t *out);
 extern kern_status_t sys_vm_controller_recv(
diff --git a/libmango/arch/x86_64/syscall.S b/libmango/arch/x86_64/syscall.S
index 2c9af73..c47d0c9 100644
--- a/libmango/arch/x86_64/syscall.S
+++ b/libmango/arch/x86_64/syscall.S
@@ -105,6 +105,7 @@ SYSCALL_GATE vm_controller_detach_object SYS_VM_CONTROLLER_DETACH_OBJECT 2
 SYSCALL_GATE vm_controller_supply_pages SYS_VM_CONTROLLER_SUPPLY_PAGES 6
 
 SYSCALL_GATE kern_object_wait SYS_KERN_OBJECT_WAIT 2
+SYSCALL_GATE kern_object_query SYS_KERN_OBJECT_QUERY 2
 
 SYSCALL_GATE futex_wait SYS_FUTEX_WAIT 3
 SYSCALL_GATE futex_wake SYS_FUTEX_WAKE 3
diff --git a/libmango/include-user/mango/object.h b/libmango/include-user/mango/object.h
index 98ff2aa..a76c938 100644
--- a/libmango/include-user/mango/object.h
+++ b/libmango/include-user/mango/object.h
@@ -4,5 +4,8 @@
 #include <mango/types.h>
 
 extern kern_status_t kern_object_wait(kern_wait_item_t *items, size_t nr_items);
+extern kern_status_t kern_object_query(
+	kern_handle_t handle,
+	kern_object_info_t *out);
 
 #endif
diff --git a/libmango/include/mango/syscall.h b/libmango/include/mango/syscall.h
index f18871e..394e2dd 100644
--- a/libmango/include/mango/syscall.h
+++ b/libmango/include/mango/syscall.h
@@ -49,5 +49,6 @@
 #define SYS_VM_CONTROLLER_SUPPLY_PAGES  46
 #define SYS_FUTEX_WAIT                  47
 #define SYS_FUTEX_WAKE                  48
+#define SYS_KERN_OBJECT_QUERY           49
 
 #endif
diff --git a/libmango/include/mango/types.h b/libmango/include/mango/types.h
index 4fc69dc..9b6ac21 100644
--- a/libmango/include/mango/types.h
+++ b/libmango/include/mango/types.h
@@ -109,6 +109,10 @@ typedef unsigned short equeue_packet_type_t;
 
 typedef unsigned int umode_t;
 
+typedef struct {
+	koid_t obj_id;
+} kern_object_info_t;
+
 typedef struct {
 	virt_addr_t io_base;
 	size_t io_len;
diff --git a/syscall/dispatch.c b/syscall/dispatch.c
index 0a02447..1446471 100644
--- a/syscall/dispatch.c
+++ b/syscall/dispatch.c
@@ -52,6 +52,7 @@ static const virt_addr_t syscall_table[] = {
 		VM_CONTROLLER_SUPPLY_PAGES,
 		vm_controller_supply_pages),
 	SYSCALL_TABLE_ENTRY(KERN_OBJECT_WAIT, kern_object_wait),
+	SYSCALL_TABLE_ENTRY(KERN_OBJECT_QUERY, kern_object_query),
 	SYSCALL_TABLE_ENTRY(FUTEX_WAIT, futex_wait),
 	SYSCALL_TABLE_ENTRY(FUTEX_WAKE, futex_wake),
 };
diff --git a/syscall/object.c b/syscall/object.c
index 5c9f939..0d3ffc1 100644
--- a/syscall/object.c
+++ b/syscall/object.c
@@ -80,3 +80,32 @@ cleanup:
 	self_thread->tr_state = THREAD_READY;
 	return status;
 }
+
+kern_status_t sys_kern_object_query(
+	kern_handle_t object_handle,
+	kern_object_info_t *out)
+{
+	struct task *self = current_task();
+
+	if (!out) {
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	if (!validate_access_w(self, out, sizeof *out)) {
+		return KERN_MEMORY_FAULT;
+	}
+
+	struct object *obj = NULL;
+	handle_flags_t flags = 0;
+	kern_status_t status
+		= task_resolve_handle(self, object_handle, &obj, &flags);
+	if (status != KERN_OK) {
+		return status;
+	}
+
+	out->obj_id = obj->ob_id;
+
+	object_unref(obj);
+
+	return KERN_OK;
+}